2015 Io Volcano Observer Proposal

The deadline for NASA's Discovery proposals was this week. 28 proposals were submitted with targets ranging from Phobos and Deimos, to Venus, to asteroids like metallic 16 Psyche, and even Enceladus.  Of course, the one that Ionians will be pulling for is the Io Volcano Observer (IVO), proposed by a team led by the University of Arizona's Alfred McEwen and managed by John Hopkins' Applied Physics Lab, which is making its second go around after also being submitted for the 2010 Discovery Announcement of Opportunity (AO).  The Martian lander, InSight, was ultimately chosen after that AO over a great set of proposed missions, which included a boat that would've sailed around Titan's great Kraken Mare.

IVO, if selected this time around, would launch in late May 2021 with an arrival at Jupiter in February 2026 after a 510 km altitude flyby of Io.  IVO would remain in an elliptical, inclined orbit around Jupiter, flying by Io eight more times during the nominal mission between August 2026 and late December 2027.  An extended mission with nearly year-long orbits is possible, providing high-resolution, imaging coverage of Io's leading hemisphere in daylight as well as collaboration with the JUICE spacecraft.  Unlike the 2010 proposal, this year's would make use of advanced, roll-out solar panels to power the probe and its five instruments, instead of the Advanced Sterling Radioisotope Generators that are unavailable to proposal teams this time around.  These instruments include: two cameras, one narrow-angle and the other wide-angle (NAC and WAC); a Thermal Mapper (TMAP); Dual Fluxgate Magnetometers (DMAG); and a suite of particle instruments (PEPI), which includes an ion and neutral mass spectrometer (INMS) and a Plasma Ion Analyzer (PIA). There is also the potential for an add-on, student collaboration instrument, a wide-angle, near-infrared camera named HOTMAP.  While the WAC, PEPI, and HOTMAP will be bolted to the spacecraft, the NAC and TMAP will be on a ± 90° pivot, allowing for off-nadir pointing of those instruments without turning the entire spacecraft.

The mission's main goals include mapping Io's active volcanism on a more global scale than Galileo and Voyager were able to obtain, measuring Io's induced magnetic field at different points in its orbit around Jupiter to provide a better estimate for the thickness, distribution, and melt percentage of its magma ocean, mapping Io's topography including its numerous mountains, and measuring the composition of the volcanic gases that are released from Io's interior.  During two of its flybys (I0 and I2), IVO will acquire gravity science using 2-Way Doppler tracking, which combined with the gravity data acquired during a few of Galileo's encounters with Io, will constrain our knowledge of mantle rigidity.  The mission will also act as a technology demonstration for Deep Space Optical Communications, which could substantial increase the data return of future missions.

On each orbit, IVO will spend a week acquiring images of Io, allowing it to map Io so changes at its many volcanoes can be observed and to monitor hot spots and auroral emissions during four different eclipses.  IVO would also use this time to help look for Europa's elusive plumes in support of Europa Clipper, which should arrive at Jupiter shortly after IVO.  During the 24 hours around closest approach, while IVO approaches and departs from Io over its polar regions, IVO will acquire several NAC mosaics of Io along with TMAP images to map heat flow and monitor volcanism.  The NAC will also be used to acquire movies of active plumes like Pele and Marduk.  Finally, right at closest approach, the spacecraft will acquire WAC, NAC, TMAP, and maybe HOTMAP imaging swaths along with INMS mass spectra and DMAG/PIA measurements as IVO sweeps north across Io.  At least 20 Gb of data (100x the Io data returned by Galileo) would be acquired during each encounter and will be played back during the apojove part of each orbit (distant monitoring observations will also be acquired to help watch for new major eruptions).

More information about this exciting mission can be found in an abstract submitted to next month's Lunar and Planetary Sciences Conference.  A fact sheet with even more details about Io Volcano Observer is also available.  NASA expects to select three (or so) finalists for Phase A studies in September with a final selection from those sometime next year.

Link: The Io Volcano Observer (IVO) for Discovery 2015 [www.hou.usra.edu]
Link: Io Volcano Observer Public Fact Sheet [pirlwww.lpl.arizona.edu]

LPSC 2010: Science Rationale for the Io Volcano Observer

For the last couple of weeks, we have been examining the Io-abstracts submitted for next month's Lunar and Planetary Science Conference.  Today we take a look at a paper submitted by Alfred McEwen and a host of co-authors from the IVO team titled, "Science Rationale for an Io Volcano Observer (IVO) Mission." For this paper, McEwen discusses the technology and science goals and objectives for the proposed Io Discovery mission.  McEwen also touches on how IVO could expand on our knowledge of Io beyond what Galileo obtained in the late 1990s and early 2000s and what the Jupiter Europa Orbiter (JEO) will get in the late 2020s.  This research will be presented as a poster at the Mission Plans and Concepts session on Tuesday, March 2.

We've discussed this proposed mission a number of times in the past. The Io Volcano Observer mission concept was first developed as part of NASA's Discovery & Scout Mission Capability Extension (DSMCE) program.  In this study, NASA hoped to get better grasp on what could be done within the Discovery/Mars Scout program cost cap if the missions were provided two, government-provided radioisotope power sources.  NASA's goal is to test the new Advanced Stirling Radioisotope Generator (ASRG) power source on one of these low-cost missions.  The ASRGs are a much more efficient power source than current RTGs, making them a smarter choice given the limited amount of plutonium available going forward.  The Io Volcano Observer (IVO) was one of nine mission concepts that were selected for further study for the DSMCE program; that study was completed back in February 2009.

For this poster, McEwen will focus on the science objectives and goals for an IVO mission, now a possible proposal for the next Discovery AO.  Some of these goals were discussed here back in September:

1. A1 - Understanding Io's current active volcanism by understanding how its active lavas and plumes are emplaced and generated.  The team plans to acquired repeated imagery of the same volcanic sites at global scales and at high-resolution (< 10 meters per pixel) in order to monitor changes at these volcanoes.  They also plan to take movies of dynamic phenomena like plumes as well as make in situ mass spectra of plume material and Io's atmosphere.
2. A2 - Understand Io's internal structure and tidal heating mechanisms.  The IVO team will use electromagnetic sounding of Io's induced magnetic field and lava temperature measurements to measure the amount of partial melting in Io's asthenosphere.  Thermal mapping in the mid-infrared (~15-20 microns) will allow the group to map Io's heat flow.  The distribution of thermal sources on Io could help distinguish the region of tidal heating in Io's mantle, whether it is in the asthenosphere or in the deep mantle close to the core.
3. B1 - Investigate the processes that form Io’s mountains and paterae and the implications for tectonics under high-heat-flow conditions that may have existed early in the history of other planets.  This will be accomplished through high resolution stereo mapping of large portions of Io's surface, with particular emphasis on areas where we already have at least medium resolution imagery, in order to look for topographic changes on a time-scale of decades (42 years between Voyager 1 and the arrival of IVO in 2021).
4. B2 - Understand how Io affects the Jupiter system.  They plan to accomplish this through in situ measurements of the composition of Ionian volcanic products, Io's atmosphere, and the plasma and neutrals in near-Io space. They also plan to study how Ionian material is lost to Jupiter's magnetosphere.  Finally, they will remotely monitor Io's sulfur dioxide atmosphere and Na-D and OI emissions.
5. B3 - Search for evidence for activity in Io's core and deep mantle by looking for an internal magnetic field in addition to the induced field discovered last year.  Resolving the conundrum of why Io can be so active and not have an intrinsic field might help us better understand how planetary magnetosphere are created.  They also plan to investigate the neutral and plasma densities and energy flows in the Io plasma torus, plus their variations over time, and characterize the ionic radiation belts in the vicinity of Io and their influence on the surface.

In addition to these science goals, a major technology goal for this mission is to study the effectiveness of the new ASRGs. One way to accomplish this is to extend the life of the mission past its primary mission of 7-8 years (including cruise to Jupiter and Io).  They could either expand IVO's orbital period to 1 year to test the ASRGs for their entire nominal lifetimes (~14 years), or they could tighten the orbits to test how well the ASRGs handle the Jovian radiation environment.  ASRGs are needed for an Io mission as the rapid flybys require fast turn times, which a non-gimbaled solar panel wouldn't support and a gimbaled solar panel may not be stable enough and too expensive for a Discovery-class mission.  The inclined orbits of IVO would result in low doses per flyby (10 krads compared to 85 krads for the average JEO flyby), so that actually wouldn't be the limiting factor for a solar-paneled Io mission, the high turn rates and high data rates during the encounters would be.

Finally, the IVO team compare the possible science generated by the Io Volcano Observer and other missions to Io: Galileo and the Europa/Jupiter System Mission.  Galileo's instruments were designed before the discovery of volcanism on Io so the camera and near-infrared spectrometer were not optimized to take advantage of this discovery, and the limited downlink bandwidth brought on by the high-gain antenna failure didn't help.  Compared to the Jupiter Europa Orbiter, IVO would fly over Io's polar regions, mapping the heat flow in those areas and performing sounding of Io's induced magnetic field.  The instruments can also be designed to specifically perform measurements needed for Io that might not be possible with those on the Jupiter Europa Orbiter, such as the near-simultaneous color imaging needed for color measurements.  JEO would accomplish some Io science that would be complementary to that of IVO, such as ground-penetrating radar and laser altimetry.  One interesting possibility is a simultaneous close-up observation with both IVO and JEO.  If IVO's mission at Jupiter and Io is extended with year-long orbits, its extended mission could overlap with the Europa/Jupiter System Mission.

Link: Science Rationale for an Io Volcano Observer (IVO) Mission [www.lpi.usra.edu]

Io Presentations at EPSC

While normally I remember to cover the big four conferences for planetary science each year (LPSC in March, AGU in May and December, and DPS in the fall), I often forget about the main European planetary science conference, the European Planetary Science Congress or EPSC.  Io science tends to be dominated by American institutions like the University of Arizona, the Jet Propulsion Laboratory, and Arizona State University, so a European conference would be expected to have less Io coverage than those held in the US.  However, this year, three talks and one poster were presented last week in Potsdam, Germany.  Let's take a look at the abstract for these four presentations:

• The last talk in the Satellite Atmospheres session this past Thursday, September 17, was titled, "First detection of Io's atmosphere at 4.0 micron" and was presented by Emmanuel Lellouch et al. Lellouch and his colleagues observed Io in the near-infrared using the CRIRES spectrometer at the Very Large Telescope in Chile in July 2008.  These measurements allowed the authors to observe an absorption band of sulfur dioxide gas at 4.0 μm.  With the adaptive optics system at VLT, they were also able to spatial resolve variations in the absorption band, looking for differences in atmospheric column density between the polar region and the equator.  Lellouch et al. believe that these observation open up a new avenue for monitoring Io's dynamic atmosphere.
• The Satellite Surfaces and Interiors oral session this past Wednesday, September 16 hosted two Io talks.  The first was titled, "Volcanism on Io: New Insights from Global Geologic Mapping" and was presented by David Williams et al.  This talk and abstract provide an update to the Io geologic mapping project, a subject Williams presented at this year's Lunar and Planetary Sciences Conference, which I discussed in greater depth earlier this year.  This geologic map displays the distribution of various morphologic and color units across Io's surface.  Using software such as ArcGIS™ will allow researchers to use the map to conduct various lines of research, including comparing the areas of various mountain units with their heights, looking at the areal extent of the various plains units, and seeing how ongoing volcanism change these areal extent of the different lava flow units.  The authors also plan to assess the distribution of different flow units to assess regional variations in the style of volcanism (sulfur versus silicate volcanism, for example) and compare these units to observed volcanic hotspots to look for correlations between eruption style and unit types.  The Io Geologic map was completed in February 2009 and has been submitted to the USGS for peer review.  A similar global geologic map of Ganymede was also presented at the conference, which has garnered some press coverage (but not Io's, bah I say, BAH!) .
• The other Io talk at the Surfaces session was titled, "Continued Observations of Io's Volcanic Activity" and was presented by Imke de Pater et al.  In this abstract, de Pater briefly presents new results from observations of Io in the near-infrared using the adaptive optics system at Keck in Hawaii.  These results include new observations of volcanic hot spots on Io as well as the distribution of sulfur dioxide frost across Io's surface.  While the abstract left out specifics, the authors spent more time advocating for additional telescopic observations of Io.  Regular observation runs were conducted during the Galileo mission and the New Horizons flyby in 2007, but outside of that flyby, Io monitoring has been sparse the last few years.  Regular monitoring is important for understanding Io's heat flow and its active volcanism. de Pater et al. also advocate for the inclusion of narrow angle cameras on board Jupiter-bound missions, particularly EJSM, to provide for monitoring of Io and other satellites in the system.
• Finally, Ashley Davies, Laszlo Keszthelyi, and Alfred McEwen presented a poster titled, "Determining Io Lava Eruption Temperature: Strategies for a New Mission to the Solar System's Most Dynamic Satellite."  These authors presented a similar poster at LPSC earlier this year, which was discussed here a bit more extensively.  This abstract discusses how the desire to measure the temperature of Ionian lava using near-infrared camera observations of lava fountains and skylights (holes in the roofs of lava tubes).  The authors explain that near-simultaneous, high-resolution color imaging during Io flybys by either a dedicated Io mission (such as the Io Volcano Observer) or by another Jupiter system mission (like EJSM) would be necessary for determining these lava temperatures without the issues from short-term variability (on the order of a few seconds) of lava fountains.  The authors also state that these observations would need to be preformed over Io's night-side to avoid contamination from sunlight.

With EPSC now passed and DPS abstracts online for that meeting in two weeks, we now have to wait for AGU abstract to be posted online.  The Fall AGU meeting is scheduled for December 14-18 and abstracts for this meeting are usually posted online in mid- to late-October.  At last year's fall meeting, five Io-related talks and posters were presented, so we will see what this year brings.

Link: European Planetary Science Congress [meetings.copernicus.org]

Final Version of the Io Decadal Survey White Paper Posted

The final draft of the Io Decadal Survey White Paper has been posted online.  The white paper consists of two sections: the first summarizes the state of Io science, the justification for NASA sending additional missions, and the outstanding questions that should be addressed by future exploration of the satellite; the second discusses an exploration strategy for addressing these remaining questions.  The other submitted white papers can be found on the National Academies website; Van Kane has a good summary on his blog of these other papers.  I previously posted a note about the recommendations for future missions to Io based on an earlier draft of the white paper.

Let's take a look at the two Io white papers.  The first, Justification and Science Objectives, takes a look at the reasons why other planetary scientists should be interested in exploring Io, the outstanding questions left by the exploration of Io by Galileo and New Horizons, and the science objectives that a future Io mission or series of Io missions should attempt to accomplish.  In addition to the fact that Io is just plain awesome and everyone knows it ("Finally, as one of the most spectacular places in the Solar System, Io has unique public
appeal, and Io exploration offers many opportunities to attract and engage public interest in
planetary science."), the authors point out that studying Io provides opportunities to understand processes that are important to examine in general, including: satellite-magnetosphere interactions; the mechanics of tidal heating, an important process for Io as well as Europa, Ganymede, and Enceladus, as well as for extra-solar planetary systems; volcanism, particularly that found on the Moon and Archean Eon Earth; and the dynamics of thin atmospheres, particularly those which are strongly driven by surface temperature and vapor pressure. The authors also identified eight science objectives that an Io exploration campaign would attempt to accomplish (the sub-headings are my own notes):

1. Determine the magnitude, spatial distribution, temporal variability, and dissipation
   mechanisms of Io’s tidal heating. (We would like to add “and implications for the coupled
   orbital-thermal evolution of Io and Europa.”)
1. The latter goal can be helped by the examination of Europa to be performed by EJSM.
   
2. Determine Io’s interior structure, e.g., whether it has a magma ocean.
3. Determine whether Io has a magnetic field.
1. This fits into the previous objective.  As explained later in Part 1, understanding the state of the core, its Fe/S ratio, and its size would help us understand the result obtained by Galileo that suggests that Io does not have a magnetic field.  Resolving the conundrum of why Io can be so active and not have one might help us better understand how planetary magnetosphere are created.
4. Understand the eruption mechanisms for Io’s lavas and plumes and their implications for
   volcanic processes on Earth, especially early in Earth’s history when its heat flow was
   similar to Io’s, and elsewhere in the solar system.
1. Two good places to provide comparative studies would be the Moon and Mercury.  While these two worlds are dead as a doornail now (deader actually), earlier in their histories, they experienced volcanic eruptions similar to those we see on Io now, particularly flood basalt eruptions and pyroclastic flows.
5. Investigate the processes that form Io’s mountains and the implications for tectonics under
   high-heat-flow conditions that may have existed early in the history of other planets.
1. In addition to the high-resolution observations to be obtained by Io-centric missions discussed in Part 2 of the white paper, additional information could be gained for this goal from the Ice-Penetrating Radar (IPR) on board the Jupiter Europa Orbiter during its two of its close flybys.
6. Understand Io’s surface chemistry, including volatiles and silicates, and derive magma
   compositions (and ranges thereof), crustal and mantle compositions and implications for the
   extent of differentiation, and contributions to the atmosphere, magnetosphere, and torus.
7. Understand the composition, structure, and thermal structure of Io’s atmosphere and
   ionosphere, the dominant mechanisms of mass loss, and the connection to Io’s volcanism.
8. Investigate the neutral and plasma densities and energy flows in the Io plasma torus, plus their
   variations over time, and characterize the ionic radiation belts in the vicinity of Io and their
   influence on the surface.
   

The second part of the Io white paper, Recommendation for Missions, was more extensively discussed in my last post on this subject.  To answer Ted's comment for that post, where he suggested that IVO, a proposed Discovery-class Io mission, would be the most likely to fly, keep in mind that what is discussed in Part 2 is an exploration program, akin to what is currently going on for Mars.  For Io, this program would start with either a New Frontiers- or Discovery-class mission that would orbit Jupiter and flyby Io on several occasions.  Such a mission could be flown in the 2013-2023 decade covered by this survey.  Following this "Io Observer" mission, the next decade, 2023-2033, could see a follow-on mission that would orbit Io, providing detailed global maps using UV, visible, and near-infrared imagers and a laser altimeter, as well as measuring Io's gravity and possible magnetic fields, and deploy one or more in situ components, such as penetrators, landers, or rovers.  One important task for these in situ missions would be to measure seismic activity using seismometers.  Enough activity should be detected over a period as short as a day to provide a more detailed model of Io's interior structure.  Finally, the authors support telescopic observations of Io from Earth or from space-based platforms, including a UV telescope that would replace the capabilities that will be lost once Hubble is de-orbited and additional ground-based telescopes with adaptive optics capabilities, which would help ease scheduling pressures at telescopes such as Keck II.  These observations would allow for monitoring time-variable phenomenon at Io such as satellite-magnetosphere interactions, Io's atmosphere, and its volcanic activity.

Additional white papers can be found at the National Academies website as well as summaries at Van Kane's blog.  These white papers will be used as input into the upcoming Decadal Survey report, which will outline the direction planetary science should go within NASA over the next decade.  How much will be possible is up in the air as the planetary budget is projected to remain pretty flat over the next decade.  For Io, since the recommendations call for a fairly modest program over the next decade (one mission in either the New Frontiers or Discovery programs) with the major mission to be started in the decade following, it isn't impossible that such a program could fly.  What remains to be seen is how much NASA and the community will take to heart the first suggestion made by the authors of the Io white paper:

We recommend that NASA pursue a balanced solar system exploration program between life-focused and physical-science focused missions.

Link: Future Io Exploration for 2013-2022 and Beyond, Part 1: Justification and Science Objectives and Future Io Exploration for 2013-2022 and Beyond, Part 2: Recommendations for Missions [www8.nationalacademies.org]

Io Decadal Survey White Paper

The Planetary Science Decadal Survey is now well underway as the community discusses how NASA should spend its money in the discipline over the decade from 2013 to 2023. For the outer planets, the previous decadal survey made a Pluto flyby mission and a Jupiter atmospheric orbiter two of its main priorities. These mandates later morphed into the New Horizons and Juno missions. At this point in the process this go around, various groups in the community are producing white papers, documents that provide details as to what should be the priorities over the next decade for their subject, be it technology, planetary astronomy, Titan, Europa, or Io, for example. NASA's Outer Planets Assessment Group (OPAG) website has several drafts for some of these white papers, including the latest draft of the Io white paper. Additional submitted white papers can be found on the decadal survey website (check out some of the ones at the bottom of that page for a laugh).

The Io white paper being authored by Dave Williams from ASU with many others, including myself, in the Io community providing input. The paper is split up into two parts: Part 1 discusses why exploring Io should be important to the rest of the community and what kinds of science goals are needed for a future mission to the satellite; Part 2 explores the types of missions that should be sent to Io in the next decade and beyond.

While the first part of the white paper roughly follows the document from the previous decadal survey, explaining why exploration of Io is important, the second parts provides updates for recommendations to the NASA Space Science Division for future Io exploration:

1. A balanced program between life-focused and general exploration missions
2. A more modest (compared to EJSM) 'Io Observer' Discover- or New Frontiers-class mission
3. The support of the IVO mission, currently being studied for the next Discovery AO
4. New Frontiers-class mission concepts for the next New Frontiers AO that allows radioisotope power sources
5. An Io orbiter in the 2023-2033 timeframe to follow-up on the discoveries of a Jupiter-orbiting 'Io Observer'
6. Io in-situ missions in the same timeframe, including penetrators, landers, and rovers that would help constrain the size and physical state of Io's core and better understand Io's surface and lower atmospheric chemistry
7. A space-based ultraviolet telescope to replace Hubble with diffraction-limited capability in the next decade
8. Long-lived Jupiter missions that would provide opportunities to observe Io over long-time frames (Juno and EJSM may provide these types of observations over the next two decades)
9. Expanding the time available for planetary astronomy on 10-meter class telescopes with Adaptive Optics capability. Such time availability would allow for long-term studies of Io's volcanic activity even without a spacecraft in the Jupiter system
10. Including support for ground-based observation programs with Jupiter system missions to follow-up on discoveries of volcanic eruptions

These recommendations highlight the need to study Io's time-variable phenomena and to close the gaps in temporal coverage of Io's volcanic activity, whether it be using Jupiter-system missions (dedicated to Io or not) or Earth-based telescopes.

Link: Planetary Science Decadal Survey White Papers [www8.nationalacademies.org]

Some Quick Notes

News has been pretty quiet lately, but here are some quick notes:

• As has been pointed out to me by Michael New, the lead Discovery Program Scientist, and Alfred McEwen, the Io Volcano Observer PI, the Discovery program cost cap of $425 million does NOT include the launch vehicle, which will be provided by NASA and would not count against the cost cap for the next Discovery mission. This is good news as it actually represents an increase to the Discovery cost cap and should help more high-concept missions like IVO come more inline with that cost cap.
• John Spencer is this week's guest blogger over at the Planetary Society Blog (the regular blogger, Emily Lakdawalla, is out on maternity leave). His first post covers recent ground-based observations of Io's atmosphere. These observations were conducted from the Infrared Telescope Facility on Mauna Kea in Hawaii. Spencer is examining the data coming back (acquired over the last four years) to determine if Io's atmosphere is supported by the satellite's volcanism or sublimation of sulfur dioxide frost on its surface. His research group is using the eccentricity of Jupiter's orbit (and thus Io's distance from the Sun) to look for changes in the pressure of Io's atmosphere over the course of a Jovian year. The difference in Io's distance from the Sun between 2005 and 2009 should amount to a 400% difference in atmospheric pressure in an atmosphere that is driven primarily by frost sublimation; a 50% difference has been observed. Spencer's preliminary conclusion is that the atmosphere is primarily driven by volcanic activity but during the warm season, when Io is closer to the sun, sublimation of SO2 outpaces condensation and the atmospheric density increases. Io will be even closer to the Sun next year, so Spencer hopes to see an more dramatic effect in potential observation then.
• Mike Salway, an Australian amateur astronomer, acquired an incredible series of images showing an occultation of Io by Ganymede last month. Definitely something you all should check out!
  

Discovery AO Details Emerge

Details of the next NASA Discovery Program Mission Announcement of Opportunity have been released by NASA. The draft of the AO will be released next month, but a few of the key elements of the document are now available. Discovery missions are low-cost, Principal Investigator-led projects. For this AO, any solar system target is acceptable, excluding the Earth and the Sun. So Mars missions would be acceptable.

For an Io mission like IVO, there are a few key details to consider. First, Advanced Stirling Radioisotope Generators (ASRGs) can be used as power sources for a proposed mission. If a proposer wishes to use them, NASA will provide two of them at no cost to the project's cost cap. This decision will allow the missions developed under the DSMCE concept study program to be proposed for this AO. However, there is one problem for the Io Volcano Observer. The cost cap for the next Discovery mission is currently set at $425 million (FY10). This is $25 million less than planned for in the DSMCE program, and the IVO team already needed to find a way to cut $21 million from the cost estimate provided by JPL's Team X. So the current cost cap would make it difficult to do a mission like IVO even with the power sources provided by NASA. One point I should make though is that I am not sure if the $471 million cost estimate for IVO by Team X included the launch vehicle as that will be provided by NASA at no cost to the mission's cost cap.

According the announcement by NASA, 2-3 missions will be approved to continue to Phase A, allowing for a refinement of the mission concepts. After the completion of Phase A, one mission will be selected to go to Phase B and then on to mission completion. This setup is probably intended to prevent some of the cost overruns that have plagued many of the recent Discovery program missions like MESSENGER and Dawn. Downselection to Phase A should occur in July 2010 and then to the single mission in November 2011.

Tip of the plutonium to Van Kane.

EDIT 07/14/2009: Since this post seems to be pretty popular for people looking for info on the Discovery AO, I should point out that launch vehicle costs (along with ASRGs) are excluded from the cost cap, which should make it was easier for proposals like IVO to meet the $425 million (FY10) limit.

Link: NASA intends to release a Discovery Program Draft AO [nspires.nasaprs.com]

OPAG Spring Meeting Presentations

Well, Hey Hey all! You've probably been wondering where in the world I have been. Well, I have been around, but unfortunately there hasn't been much news lately, and I've been spending my free time playing Europa Universalis III rather than processing Io images. Sorry, but it is true. I think it was time well spent. I just conquered Constantinople. I feel rather proud of myself. So I haven't abandoned you all. I will try to post more often. I'm sure there are scraps of news I've missed.

Anyways, the presentations from the OPAG Spring Meeting are finally online. Yes, Hell has frozen over. Or maybe that was Europa. Wait, that's redundant, scratch that... I kid, I kid. NASA's Outer Planets Assessment Group (OPAG) held their spring meeting in Bethesda, Maryland last month and we have been waiting for the presentations to get posted online. Not just me, but Van over at Future Planetary Exploration has been waiting.

Two presentations caught my eye. The first is by my advisor, Alfred McEwen, and covers the Io Volcano Observer. This presentation covers much of the same terrain that we saw in the presentation given in December at the Io Workshop, but it also goes into further details over a possible tour plan and the science goals. The example tour presented includes some info about how the IVO team might plan the mission. The sample tour includes no flybys with altitudes less than 291 km in altitude, but the previous slides does point out that the do plan to try closer encounters, down to 100 km, later in the nominal mission and extended mission. Closer encounters are particularly important in order to observe small scale features on the surface (like skylights) and to use the mass spectrometer within an active plume. The sample mission assumes a different launch from the nominal January 2015 one, so again, take the sample tour with a grain of salt. Still, it would seem that the tour designers want to keep the sunlit region on Io during the flybys fairly similar, but not so similar that only half the surface would ever be visible during these encounters.

The IVO presentation also concentrates on the science objectives for the mission. These mission objectives largely cover those proposed for the Io Observer mission type available for the New Frontiers-3 announcement of opportunity (but all but impossible because NF-3 can't use radioisotope power sources). These science goals include (level 1 goals in bold):

• Understanding the eruption mechanisms for Io's lavas and plumes and how these compare to similar processes on Earth and other terrestrial planets
• Determining Io's interior structure, particularly the melt fraction of the mantle
• Determining the properties and mechanisms of Io's tidal heating and implications for the orbital evolution of Io and Europa
• Investigating the processes that form Io's mountains and other tectonic structures in the satellite's high heat flow environment
• Understanding Io's atmosphere and ionosphere and their connection to Io's volcanism
• Determining whether Io has a magnetic field
• Understanding Io's surface chemistry, including volatiles and silicates
• Improving our understanding of Jupiter system science

The IVO team feels that this mission along with the Jupiter Europa Mission, would go along way toward responding toward these goals, though many require a high data rate as a result of the fast encounters, so a large amount of data storage will be needed (~20 Gb) in order to capture all the close approach data, particularly from INMS and RCam. McEwen also stresses the synergy between JEO and IVO, making it clear that even with the Europa/Jupiter System Mission having been selected, the Io Volcano Observer will still be needed by the Io community, as it provides much more information about the polar regions, particuarly the heat flow up there, and would provide much more data on the composition of Io's lavas. Finally, IVO would help to mitigate EJSM's risk by testing the ASRG, the next generation of radioisotope power source to be used by IVO, if EJSM uses them as well.

Curt Niebur gave a presentation on the results of the Outer Planets Flagship Mission selection process. Niebur goes into detail the rationale behind the Selection Panel's decision to give higher priority to the Europa/Jupiter System mission for the next decade flagship mission. Basically, as has already been reported, the EJSM concept was seen as been more technically mature, the result of several prior mission studies over the last decade for a Europa follow-on mission to Galileo. Niebur notes several issues with the Titan concept, but the technical review basically noted that technical issues and design drivers many of the mission elements, such as the SEP stage development, the thermal subsystem, the integration of the in situ elements, and aerobreaking where not realistically reflected in the budget estimate.

Link: OPAG Spring Meeting Presentations [www.lpi.usra.edu]

How EJSM affects the Io Volcano Observer

With a mission now planned for the Jupiter system in the 2020s, how will the Io Volcano Observer proposal be affected? Would a dedicated Io mission even be necessary?

The Io Volcano Observer and the Jupiter Europa Orbiter would conduct complimentary science. Both spacecraft have high-resolution cameras capable to studying Io's surface in fine detail during flybys as well as monitoring Io's global volcanic activity from a distance. Both can conduct mass spectroscopy of Io's atmosphere and plumes as well as observe Io's thermal inertia. The Jupiter Europa Orbiter would be capable of acquiring observations not currently in IVO's baseline payload such as near-infrared spectroscopy, ground-penetrating radar, laser altimetry, and particle and plasma analysis. So seemingly, the Io Volcano Observer would not be necessary. Not so fast.

The Jupiter Europa Orbiter's instruments are designed to study Europa, with bandpasses of the various instruments and their functionality driven by that requirement. Studying the other bodies in the Jupiter system, while a level 1 science requirement, really is just gravy for the mission. JEO's unique instrumentation, such as the Ground-penetrating radar, can answer quite a few questions that IVO can't. However, the design of the payload for IVO has been defined to specifically answer questions at Io. For example, the camera on IVO would be capable of observing volcanic activity with multiple filters with less than 0.1 seconds between color frames. This allows fairly accurate measurement of the lava temperatures at Io's volcanoes. This can constrain the amount of partial melting in the mantle needed to support the eruption temperature observed. The band passes on the Thermal Mapper, rather than being selected to search for warm spots on an icy world, will be selected to explore different volcanic processes on Io of different ages as well as looking at the silicate composition of these flows.

Also, don't forget that IVO will perform at least seven Io flybys during its 1.5-year primary mission (starting in early 2021), three more than the encounters planned for JEO. In addition, IVO has enough margin in its radiation shield to support seven more encounters, which could be spaced out by as much one year apart to help study the long-term life time of IVO's power source, the two Advanced Sterling Radioisotope Generators (ASRGs). This extended mission could help fill the gap between IVO's primary mission which ends in late 2022 and JEO's arrival in late 2025. This provides the potential for spacecraft monitoring of Io covering almost eight years, similar to Galileo's time at Jupiter.

While the Jupiter Europa Orbiter will perform quite a bit of science at Io, since the instruments are not optimized for Io science, there is still a need for a dedicated mission like Io Volcano Observer. Potentially JEO could allow IVO to trim some costs by reducing some of the redundancy, like the magnetometer instrument. However, the priority for an Io mission may go down in comparision to other potential Discovery-class missions with the EJSM arrrive only a five years later than IVO.

Io Volcano Observer at LPSC

The Lunar and Planetary Science Conference will see two Io Volcano Observer posters. The first, by Alfred McEwen et al., is titled "Io Volcano Observer (IVO)". This poster will provide an overview of the mission concept, with the abstract providing quite a few details of the planned payload. The second, by Keszthelyi et al, is titled "Optimal Wavelengths for Studying Thermal Emission from Active Volcanoes on Io". This poster will look at some of the work that has gone into filter selection and instrument design for IVO's radiation-hard camera (RCam) and Thermal Mapper (ThM).

Much of the information in McEwen's abstract was previously reported on in my post, The Uber Io Volcano Observer Post, so I don't think I need to completely repeat myself. The abstract does include a clearer description of the imaging system to be used on IVO, RCam. The camera would use a 2000x2000 CMOS detector. The half of the detector will allow RCam to be used as a clear-filter framing camera, for taking opnav,clear filter global images, and plume movies. The other half "will be covered by up to 15 spectral filters from 200-1000 nm, each covering ~64 lines for digital Time-Delay Integration (dTDI)." For 256 lines, the instrument will have 16 sets of 4 filters, with each filter using 4 lines. The four filters McEwen's suggests using are 400-600 nm (blue-green), 600-800 nm (red), >800 nm (IR1), and >950 nm (IR2). This would allow RCam to take near-simultaneous color images that will be necessary for measuring the hottest lava temperatures as they can change over times scales of less than a second. Other filters that RCam could use include UV bandpasses (for atmospheric processes and for looking at SO2 frost), other narrow filters for looking at atmospheric composition (Na, O), mineralogy bandpasses from 800-1000 nm, and methane bands (for looking at Jupiter's atmosphere).

The second abstract by Keszthelyi et al. takes a look at the best filters to use on RCam and Thermal Mapper for measuring lava temperatures. Different bandpasses would work best for measuring lavas of different ages. For example, RCam would be used to look at lava less than a second after they emerge from the surface (such as at a lava fountain) as well as magma in lava tubes made visible through skylights. This would be supported by the two near-infrared bandpasses on RCam. Ratioing pixel values between the two would allow scientists to calculate eruption temperatures between 1200 and 1800 °C. The digital Time-Delay Integration system used by RCam would also support the need for less than 0.1 seconds between acquisition of the different color filter data.

The Thermal Mapper will use up to 10 bands in the infrared portion of the spectrum to examine Io's surface composition, thermal inertia, and thermal emission. Some of the bands that will be included would be selected based on the type of volcanic process mission scientists wish to examine. These processes occur at different time scales, which based on the cooling rate of lava on Io, can be related to different peak temperatures. The wavelengths picked (2, 3, 4, 6, and 8 microns) were chosen because they cover peak emission wavelengths for each of the time scales the scientists want to look at (processes that occur over a period of seconds, minutes, days, and months). Other bands the scientists would hope to include are 15 and 20 microns that would be used to search for SO2 at its triple point as well as to look at global heatflow. Additional bands could be included to search for the Christiansen Feature between 7.5 and 9.5 microns, which would provide additional information on the mineralogy of Io's lavas. The Christiansen Feature increases in wavelength with decreasing SiO2 content. So the CF for minerals typical of felsic lavas like rhyolite would be closer to 7.5-8 microns, while the CF for minerals typical of mafic lavas, the dominent type on Io,would be closer to 8.5-9.5 microns.

Way cool stuff!

Link: Optimal Wavelengths for Studying Thermal Emission from Active Volcanoes on Io [www.lpi.usra.edu]

The Cost of the MSL Launch Slip

Van Kane has a couple of posts from yesterday's special Planetary Science Subcommittee (PSS) meeting on the effects of the Mars Science Laboratory (MSL) launch slip. Van listened in on the telecon, and posted about it on his Future Planetary Exploration blog. This new cost overrun could adversely affect the next Discovery Announcement of Opportunity and increase risk for Juno, a New Frontiers-class mission bound for Jupiter.

In December, the launch for the next-generation Mars rover slipped from September-October 2009 to late 2011. This launch slip increased the cost of MSL by $400 million, which must be absorbed, some how, by NASA's planetary science budget. At the PSS meeting yesterday, several recommendations were presented for where this $400 million would come from. Before deciding on where the funds would come from, NASA set a few (very good) ground-rules: currently planned missions would be launched as scheduled, though the Juno and MSL launch windows over lap, which will need to be worked around; the New Frontiers AO will proceed as planned; R&A funding won't be touched (considering that this is where my salary comes from, I for one love this rule); and the Outer Planets Flagship mission will proceed as planned.

According to Van, the vast majority of the over run would be accommodated by using funds currently allocated for technology development for future Mars missions, such as mid-size rovers and the sample return mission. The rest, approximately $47 million, could come from delaying in the next Discovery mission AO (affecting the Io Volcano Observer proposal) by a year, reducing the reserve funds for the Jupiter-bound Juno mission, or delaying the International Lunar Network mission.

Presentations from this special meeting have not yet been posted online.

Link: Future Planetary Exploration [futureplanets.blogspot.com]

The Uber Io Volcano Observer Post

My boss Dr. Alfred McEwen has given me permission to post the presentation on the Io Volcano Observer (IVO) mission concept he gave a few weeks ago at the Io Workshop in Berkeley, California. You can find the presentation here. The presentation covers mission design, mission goals, baseline and optional payloads, and risk assessment.

Mission Design

The current mission design calls for a January 2015 launch (with a window from late 2014 to early 2015). IVO would be launched into a Venus-Earth-Earth gravity assist trajectory, similar to the interplanetary path taken by Galileo between 1989 and 1995. Calibration for IVO's various instruments would be performed during one of the Earth encounters, though McEwen does note that an asteroid encounter during one of the apohelions could be used as a dress rehersal for the Io flybys.

After a six-year cruise, IVO would enter orbit around Jupiter in 2021. Prior to Jupiter orbit insertion, IVO would perform its first flyby of Io. While other information I have found suggested that no science would be acquired during this first encounter, McEwen presentation points out that the reason for performing this encounter is to acquire unique equatorial science since the encounter doesn't actually reduce the delta-V, like the inital Io flyby did for Galileo. IVO would be inserted into an inclined, 200-day-long initial orbit following JOI.

During IVO's orbital tour, planned to last at least 1.5 years, the spacecraft would flyby Io at least six more times, with the goal of having more than ten flybys with the help of an extended mission. With the various sources I have, I am not certain if they plan to have six flybys during the primary mission with at least four more during an extended mission, or if the six-flyby number is only a baseline for mission success. The trajectory design calls for the Io flybys to also be used to "pump down" the spacecraft's apojove, eventually bringing IVO's orbital period down to 30 days. The first few flybys of Io would be further out, with altitudes between 500-1000 km, until estimates of Io's position are refined. Later encounters can then be brought down to altitudes approaching 100 km, supporting magnetometer and mass spectrometer science. Like Galileo, data would mostly be taken during the few days surrounding perijove and would be transmitted to Earth near apojove, though the much greater bandwidth with IVO would support more apojove science, such as imaging of Jupiter and eclipse observations of Io and Europa. Also, thanks to IVO's increased bandwidth, up to 20 Gb of data would be returned after every flyby, much greater than Galileo's entire Ionian dataset. I can't recall, but that maybe more data than Galileo returned during its entire Jovian tour.

For planetary protection purposes (God forbid we contaminate poor Amalthea), the spacecraft would be impacted with Io at the end of its life. However, several end of mission scenarios have been developed, including one that would put IVO into very large orbits, with periods up to one-year in length, in order to monitor Io for up to a decade and to perform a lifespan test for the Advanced Stirling Radioisotope Generator (ASRG), the next-generation power source to be used by IVO. In another scenario, IVO's perijove would be raised to pull it out of the worst of Jupiter's radiation belts, again to extend the spacecraft's life, though there maybe issues with the requirement to dump IVO on Io at the end of the mission.

Mission Goals

Io Volcano Observer, being half a science mission and half a engineering test, has a very focused set of mission goals. As you can see in the slide at right, the primary objective of this study is to see if an Io mission can be accomplished with a Discovery budget, assuming NASA furnishes the ASRG and NEPA.

The baseline mission was designed as simply as possible while still accomplishing a focused set of science goals. From the presentation, these include:

1. Understanding active Ionian volcanic processes
2. Understanding the process of tidal heating
3. Understanding loss of material from Io and following that material to the magnetosphere, plasma torus, and neutral clouds

IVO's planners also want to test out the ASRG for as long as possible, thus the desire to extend the lifespan of IVO as long as possible before crashing it into Io. In additions, measurements of the radiation environment will help planners of future missions to the Jovian system.

There are also secondary goals to study the rest of Jovian system. Most of these observations would be acquired near apojove. These include: monitoring of Jovian clouds systems near the poles (complementing data from Juno), distant observations of the Galilean satellites including Europa's atmosphere, close-up observations of Jupiter's inner moons near perijove, and observations of Jupiter's rings and the Io Plasma Torus. Due to data volume restrictions on the later, shorter orbits, many of these observations would be acquired during the initial, 200-day orbit, when data volume would be more plentiful.

Payload

At the Io workshop, McEwen presented details on the planned baseline payload as well as other instruments that could be used on IVO. With this payload, McEwen and his team hope to accomplish the science goals discussed above.

The baseline payload for IVO includes the following instruments: a narrow-angle camera with an angular resolution similar to Galileo, a thermal mapper similar to THEMIS on Mars Odyssey, an Ion and Neutral Mass Spectrometer, and magnetometers. Other potential instruments outlined by McEwen include a wide-angle camera, a near-IR spectrometer, and an EUV/FUV spectrometer.

The narrow-angle camera, as outlined by McEwen, would provide medium-resolution surface monitoring and high-resolution surface imaging during flybys, while keeping noise to a minimum. Unlike most spacecraft imagers in use, the camera would use a CMOS focal-plane system with both framing and pushbroom modes. The fast readout times for the CMOS system would help keep radiation noise down by reducing the amount of time between the image exposure and its storage in memory. The CMOS detector would be split up so that the bottom half of the detector (1000 lines by 2000 columns), would be used for clear filter, framing-mode imaging, similar to Cassini's ISS. Up to half of the detector would be used for color filter, pushbroom imaging, similar to the Mars Reconnaisance Orbiter's HiRISE camera. This upper section would consist of up to 15 color filter strips of 64 lines each. These strips would use digital Time-delay Integration to produce nearly simultaneous color imaging (necessary for lava temperature measurements), super-resolution, and faint-target imaging. At minimum, McEwen's group would like to include broadband UV, blue-green, red, and near-IR dTDI lines, though other filters could be included, mostly narrowband filters designed for spectroscopy.

IVO's thermal mapper would be designed much like Mars Odyssey's THEMIS instrument. The instrument would include at least three bandpasses between 2 and 20 microns and would have a resolution about 12.5x coarser than the NAC (assuming new detectors are used, compared to THEMIS). With Thermal Mapper, IVO planners hope to map and monitor Io's thermal emission, perform thermal emission spectroscopy, and analyze Io's polar thermal emission and compare it with results from Galileo at low latitudes. For a baseline mission, the expected bandpasses would be at 2, 5, and 20 microns, though more bandpasses maybe possible. Some that interest IVO planners occur between 7 and 9.5 microns, wavelengths diagnostic for silicate mineralogy.

The Ion and Neutral Mass Spectromter (NMS) was covered recently in a blog post, so check that out for details of that instrument. IVO planners seem confident that they can detect most of the expected species in Io's atmosphere (like SO₂, SO, O, and NaCl) thanks to its high signal-to-noise ratio and 1-300 amu mass range.

The final pieces of the baseline payload are a pair of fluxgate magnetometers. These very small magnetometers would be attached to 1-meter long brackets bolted to the spacecraft. These magnetometers would be similar in design to those carried on recent ESA planetary missions. Now whether they would actually find a magnetic field at Io...

These instruments would be bolted to the top deck of the spacecraft, below the High-gain antenna. This would force decisions between having a gravity pass and a remote-sensing pass, much like Cassini. Much of the electronics for these instruments would be stored below this top deck, in a radiation-shielded "vault", in hopes to reduce the chances for radiation affecting measurements.

Risks

A major limiting factor for the lifespan of IVO is the high charged particle environment near Io. Even with the high-inclination orbits, IVO planners expect betwen 115 and 230 krads, though the spacecraft electronics may have a much reduced exposure during the primary mission.

Another issue is the current projected price tag. A JPL Team X assessment in November came up with a cost $471 million. I'm not sure if that is for the baseline mission, but at least $21 million will need to be trimmed from the estimated budget to get IVO within the Discovery costcap.

Conclusion

This presentation lays out a pretty compelling case for a cost-effective mission to Io. As of earlier this month, IVO planners were preparing to finish their final report for the DSMCE program and were looking forward to submitting this proposal for the next Discovery Announcement of Opportunity coming (hopefully) sometime around mid-year.

Link: Io Volcano Observer (IVO) [pirlwww.lpl.arizona.edu]

Van Kane covers IVO

Van Kane, over at the Future Planetary Exploration blog, has posted an excellent overview of the Io Volcano Observer (IVO) mission concept. I have covered this proposed Discovery-class mission several times in the past, using info from an abstract and presentation by IVO's Principal Investigator, Alfred McEwen at this year's Lunar and Planetary Laboratory Conference back in May and from an online presentation by one of the instrument Co-I's, Peter Wurz.

Kane, in his blog post, took a look at a presentation given at this year's Io Workshop, held at the UC Berkeley last week, given by Alfred McEwen. Among the new details on the proposal include a refinement on the mission profile, with a proposed launch now seen in January 2015 with a Venus-Earth-Earth trajectory to Jupiter. Jupiter Orbit Insertion, including the first Io flyby, would occur in 2021. IVO would be injected into a high-inclination orbit around Jupiter in order to limit the spacecraft's exposure to the planet's radiation belts, thus extending the lifespan of the spacecraft. As previously reported, the initial orbit would be an eccentric, 200-day orbit, which would be reduced in length using later Io flybys. The baseline mission calls for six Io flybys over a 18-month long primary mission, with more flybys in a possible extended mission.

The current projected mission cost is $471 million, slightly above the current Discovery mission cost cap of $450 million and also assumes that the ASRG power sources would be provided by NASA.

Many of the details of the instruments planned for IVO remain similar to those reported here before. Two magnetometers appears to have replaced the radiation detector in the baseline payload.

Link: Io Missions - Part 3: Io Volcano Observer [futureplanets.blogspot.com]

More Info on the Io Volcano Observer

Okay, it has been a while since I have discussed the Io Volcano Observer (IVO). This mission concept was developed in response to the Discovery and Scout Mission Capability Extension (DSMCE, pronounced DOS-MICE). The DSMCE program was started by NASA to examine the viability of Discovery-class mission powered by next-generation radioisotope power generators provided to the PIs at no cost to the mission. The IVO study is headed by Alfred McEwen at the University of Arizona with scientists and engineers at Ball Aerospace, USGS-Flagstaff, JPL, and the University of Bern in Switzerland.

Check out my previous posts on IVO, particularly those from LPLC after a talk by Dr. McEwen, and one based on the conference abstract.

Well, obviously, despite the fact that the initial study is finished, very little has shown up on the web. There is a good reason for that. There is a very good chance that McEwen et al. will submit a proposal for the mission with the Discovery Announcement of Opportunity is released next year (April 2009?). Despite this, I have found a new online source for information on the mission, particularly on the Ion and Neutral Gas Mass Spectrometer (INMS) from a presentation given by the Peter Wurz of the University of Bern in October.

The presentation's fifth slide provides an overview of the IVO mission, mostly with details that were previously known. Three instruments are planned for IVO's payload: a narrow-angle camera, a thermal infrared imager, and an ion and neutral mass spectrometer. A Radiation Detector and Ultraviolet Spectometer are not mentioned, like in Dr. McEwen's presentation in May. The baseline mission plan remains much the same as was outlined by Dr. McEwen: a launch planned for 2013 (with a backup in 2014), Jupiter orbit insertion in 2020 with the first Io flyby in June 2020 (a year later than the baseline mission presented in May), and a science phase that runs 16 months to October 2021. Considering that the initial Jovian orbit following the first Io flyby is expected to run on the order of 200 days, the other nine flybys are planned between December 2020 and October 2021 occurring on the order of about once a month.

Dr. McEwen's presentation at LPSC went into a bit of detail of the Narrow-angle camera and the thermal imager, but he ran out of time before he could get to the INMS. Therefore, the presentation by Wurz is complementary to McEwen's. IVO's INMS is a time-of-flight mass spectrometer with some design heritage with the ROSINA instrument on Rosetta. P-BACE, a spectrometer similar to the one planned for IVO, was developed at Bern and was aboard MEAP, a stratospheric balloon mission that recorded measurements of the circumpolar wind patterns between Sweden and Canada. Based on the measurements acquired by P-BACE, Wurz and Thomas expect to be able to measure most of the atmospheric species expected at Io, such as sulfur dioxide, sulfur, hydrogen sulfide, sodium, potassium, and oxygen.

The scientific goals for IVO's mass spectrometer include: measurements of Io's atmospheric scale height and major components; a search for differences in these measurements as a result of temporal changes, geography, or day-night cycles; measurement of atmospheric loss mechanisms and rates (due to sputtering for example); and measurements from within a volcanic plume.

Overall, the INMS looks like an interesting addition to the mission. The instrument could also take on increased importance as a similar instrument may not make it on the Europa Orbiter since the instrument would push the cost of the EO above that project's budgetary "sweet spot." So even if Europa Orbiter is selected as the next Outer Planets flagship mission, IVO might still get proposed because of unique measurments a mass spectrometer could make. IVO could also provide a useful stopgap between New Horizons and EO (planned to arrive in the late 2020s).

(Before you ask, the graphic at the top is an old, 1990s-era graphic of IVO, so just ignore the solar panels ;)

DPS NASA Night

NASA Night at DPS just ended a few minutes ago, and I took the opportunity to view the presentations online. In a bit, it should also be archived for everyone to view here. NASA Night is an opportunity from program heads at NASA HQ in Washington to speak to the Planetary Science community about what NASA HQ is doing with respect to the Planetary Science Division at NASA and for them to get input from the community. These events can often be contentious as changed made by NASA HQ with how things are done and what missions and announcements of opportunity are coming up can effect people's funding and lively hood.

There were two presentations given at NASA Night. The first was given by the director of NASA's Planetary Science Division (PSD), Jim Green, and the second was given by the director of SARA (the grant program at NASA), Max Bernstein. There was a question and answer session following each talk.

Jim Green's talk provided the most meat at NASA Night. He discussed the problems the Mars Science Laboratory has been having lately, the upcoming New Frontiers and Discovery Announcements of Opportunity (AO), the next Decadal Survey, the Outer Planets Flagship Mission, and the new travel and conference funding for NASA employees. Obviously he covered quite a bit of territory.

As is known by now, the Mars Science Laboratory recently incurred yet another cost overrun, more than the overguide threshold requied by NASA. This resulted in a review with the adminstrator. From this meeting last week, the adminstrator agreed to keep MSL on the current launch schedule for 2009. However, funding issues remain. The PSD will perform a review of the extent of the overruns, as the JPL estimates appear to lack credibility. Once this is done, the PSD will determine how to cover the costs. Green assured the audience that he will use the Planetary Science Subcommittee's recommendations to only get the funds from missions outside the Mars Program (like Juno) as a last resort, with funding mostly coming out of JPL and the Mars Program (possibly affecting MAVEN). The PSD will then worth with the White House Budget Office and the Congress to finalize a resolution, though with MSL now 30% (or more) over the initial budget estimate, Congress could decide to cancel MSL. At the moment, there are no plans to descope instruments on MSL.

Green next discussed the next Decadal Survey. Decadal Surveys act as a guide for NASA when selecting missions and instruments over the next 10 years. The last Decadal Survey in 2001 promoted Pluto/Kuiper Belt flyby and Jupiter missions as the top priorities for the New Frontiers program, which resulted in the selection of New Horizons and Juno. The last survey also excluded the Mars program from the priority list, since at the time (and still to this day) the Mars program is separate from missions to the rest of the solar system. The next Decadal Survey, scheduled for 2011, will include Martian and Lunar missions. Extrasolar planets will be covered by the Astrophysics Division.

Green next discussed the Discovery and New Frontiers programs. Green briefly covered the DSMCE program (pronounced DOS-MICE). This was a mission concept study program to see what kinds of Discovery-class missions could be performed if the proposers were given two free Stirling Radioisotope engines for energy, rather than solar panels, which have been used for all previous Discovery-class missions. One of the concepts they are looking at is the Io Volcano Observer, a study led by my advisor, Alfred McEwen. Reports from these studies are due in December. The next Discovery AO is planned for 6 months after the New Frontiers AO. Green said that the decision to use government-furnished Sterling engines for this next AO has not been made yet. The next New Frontiers AO is currently being developed. The draft AO will be released soon, and will be available for public comment for three months before the final AO is posted.

Green then briefly covered the Outer Planets Flagship Mission selection. Nothing new to report since the PSS meeting a couple of weeks ago. Green did confirm that the change in the planned launch window, from 2016-2017 to 2018-2022, was done so that the NASA-provided mission components would launch closer in time to the ESA-provided components.

Finally, Green reported that NASA is severely restricting funding for NASA employees to go to conferences as well as sponsorship of conferences. This restriction includes attendance at DPS, LPSC, and AGU. This would limit the number of civil servant employees at these conferences, such as those from JPL and Ames. Jonathan Lunine, during the Q&A session, brought up the argument that this restriction, which maybe temporary, would limit grad students exposure to federal civil servants, which could make employment at NASA facilities less attractive. In additional, the restriction could cause a drop in membership to professional organizations like AGU and AAS as NASA employees would no longer benefit from the reduction in attendance fees at conferences.

Don't forget, the Galilean Satellites session is scheduled for tomorrow morning at 5:30am EDT.

Io Volcano Observer at LPLC

Yesterday was the second and final day of the Lunar and Planetary Laboratory Conference in Tucson, Arizona. This is a small conference where researchers at the University of Arizona's Lunar and Planetary Laboratory can share their current work with their colleagues here. Many of the talk in the morning where dedicated to dynamics and space physics. I am amazed I stayed awake...

The afternoon sessions included Titan and other satellites in the Solar System. I gave a talk on Cassini images of Titan, particularly those of Titan's polar regions. Alfred McEwen, my advisor, gave a talk on the Io Volcano Observer (IVO, pronounced eye-voh), a mission concept in the Discovery & Scout Mission Capability Expansion (DSCME) program. I have reported on this concept study previously and on the abstract McEwen submitted to the conference.

The talk provided a few new details on this mission concept. The IVO team is aiming for a 2013 launch on an Atlas V with a back-up launch date in 2014. The spacecraft would be launched into a Venus-Earth gravity assist trajectory with an arrival at Jupiter in the 2019 timeframe. Once at Jupiter, IVO would flyby Io shortly before Jupiter orbit insertion, which would lower JOI delta-V and provide an insurance flyby in case any issues occur during the JOI burn. Once at Jupiter, IVO would be injected into a 200-day orbit around Jupiter with a 45 degree inclination.

Over the course of the 1-2 year mission, IVO would use 5-10 Io flybys to bring its orbital period down to 30 days. Each flyby would have a close-approach distance between 500 and 1000 km with 100 km flybys possible later in the mission. The high-inclination orbit would provide much needed polar coverage, which would be complementary to observations acquired by Galileo and the Europa orbiter mission. Flybys would occur at similar solar longitudes on Io to reduce the variables when comparing images between flybys.

The base payload for IVO includes a narrow-angle camera, a Thermal Imager, a Neutral Mass Spectrometer, and a Radiation detector for a total payload weight of 34 kg (44 kg with 30% margin). The nominal narrow angle camera planned would weigh 15 kg and would have a resolution of 10 microradians per pixel (the same as Galileo SSI). The goal for this camera is to observe Io's ever-changing surface by observing the same volcanic features during each flyby. The camera would also be used to measure Io's limb topography, which would help constrain Io's tidal bulge and thus provide constraints on Io's current tidal heating. The camera will make use of active pixel sensors, which have increased radiation hardness compared to traditional CCDs. These sensors will also allow the IVO team to acquire simultaneous multi-spectral imaging. This would make acquiring color mosaics a much simpler task as well as help support lava temperature measurements, since lava fountains can change on the order of seconds.

The Thermal Imager would be similar to the THEMIS instrument on the Mars Odyssey spacecraft. The IVO team is looking for an instrument that would acquire near- to mid-IR imaging at 3, 8, and 20 microns, to measure Io's heat flow. Assuming something akin to THEMIS is used (which is possible considering that the PI for THEMIS, Phil Christensen, is on the IVO team), the Thermal Imager would have a 4.6 deg. FOV with 250 microradians/pixel resolution (effectively 1 km/pixel per 4000 km).

Unfortunately, Alfred was nearing his alloted time by the time he finished discussing the Thermal Imager so he didn't spend time covering NMS, UVS, and the Radiation Detector. He pointed out that the "Powerpoint" mission might have a chance in Hell of flying, considering that Io is a world of fire and brimstone, there is a team member named Dante, and that Alfred will be 66 years old when IVO arrives at Jupiter (assuming that IVO flies on the back-up 2014 VEEGA trajectory).

More Details on Io Volcano Observer

As mentioned last month, NASA has commissioned several concept studies for Discovery-class mission that make use of the new Advanced Stirling Radioisotope Generator (ASRG) power source, a more efficient RTG that makes use of plutonium for power. One of these concepts is the Io Volcano Observer (IVO), a mission to study Io's volcanic activity.

The leader of the study, Alfred McEwen, submitted an abstract on the mission concept to the Lunar and Planetary Laboratory Conference (LPLC) to be held next week in Tucson. I will be there giving a talk on the state of Cassini Imaging, particularly imaging of Titan. The abstract makes public a few more details on the study. The IVO team envision a small spacecraft that orbits Jupiter in a highly inclined orbit, encountering Io at every periapse. The high-inclination orbit helps to reduce IVO's radiation exposure during periapse. Each orbit would last between 30 and 200 days, though shorter orbit would provide better distant monitoring.

Due to the low-cost of the mission, the payload has to be kept simplistic. The team has currently include a baseline payload of a narrow-angle camera (with some color imaging capability), a thermal imager (capable of mapping Io's thermal emission at 3, 8, and 15 microns, and at some silicate absorption bands), a Neutral Mass Spectrometer, and a Radiation detector. Other potential instruments include a Wide-angle camera, an ultra-stable oscillator (used for gravity measurements), a near-infrared spectrometer (I guess a toss-up between this and the thermal mapper), an ultraviolet spectrometer, and a magnetometer.

The team has also outlined the scientific goals for this mission which include understanding Io's volcanic processes, composition, heat flow, and environment.

Link: Mission Concept: Io Volcano Observer (IVO) [www.lpl.arizona.edu]

Io Volcano Observer

Leonard Dudzinski, the Program Executive for NASA's Radioisotope Power Systems Program, presented details on the availability of plutonium-based power sources for space missions, on new types of Radioisotope thermoelectric generator (RTG)'s, and on a program to test one of these new types of RTGs on the next Discovery-class mission.

Currently, the plutonium used to power some of the planned upcoming missions (like the Outer Planets Flagship Mission, the Mars Science Laboratory rover, and the next Discovery mission) is purchased from Russia. New production here in the US may start up in the middle of the next decade, but that won't be enough to supply the missions planned in the NASA roadmap. To improve this outlook, new technology and more efficient RTGs will be needed. Enter the Advanced Stirling Radioisotope Generator (ASRG). This RTG uses 75% less plutonium per unit but provides 115-130% more watts than the next-generation MMRTGs to be used on the upcoming Mars rover and Outer Planet Flagship missions. Plus the ASRG weighs less and costs less per unit.

While the ASRG will be a boon for missions that require power from radioisotopes, it is as yet not flight tested. This is why the next Outer Planets Flagship mission will use the less efficient MMRTGs. NASA has decided to make two ASRGs available for the next Discovery-class mission, to be launched in 2013-2014. All previous Discovery-class missions have used solar panels for power. The cost of the RTGs will not be counted against the Discovery mission cost cap. To study the feasibility of such a plan, NASA has commissioned nine mission concept studies to see if such mission can fit within the Discovery cost cap.

And the big news: one of these mission concept studies is the Io Volcano Observer. This study is being run by Dr. Alfred McEwen of the University of Arizona (my boss). Few details are publicly available at this point on this mission concept, but the idea would be for the mission to perform multiple flybys of Io. I had thought this was a study for a New Frontier-class mission. I didn't even think of this being a Discovery-class mission.

The concept study should be finished in late September. No word on when this will be available.

Link: Radioisotope Power for NASA's Space Science Missions [www.lpi.usra.edu]