EJSM Instrument Mission Workshop

The presentations from the Europa Jupiter System Instrument Mission Workshop are available. You will have to download Acrobat Reader 9 to view the presentations, but you can also hear the presenters. (If you don't want to listen, just hit pause after opening the presentations and then you can page through them.)

A couple of tidbits caught my eye. They may be old news, but this is the first time they've caught my attention:

The NASA Europa Jupiter Orbiter will carry 16GB of memory to record data during satellite flybys and observations of Jupiter. This memory does not need to be functional in Europa orbit (there's 1GB of radiation hardened memory for that). This means that substantial data could be returned from each satellite flyby.

The ESA Ganymede Jupiter Orbiter strawman instrument payload now includes a narrow angle camera. This would substantially increase the resolution of observations of Jupiter and Io (as well as increasing coverage of Europa and Ganymede). No details on the image system.

The following chart caught interested me. If budgets prevent flying a Jupiter Europa orbiter, a Jupiter orbiter conducting multiple satellite flybys would be a cheaper alternative. This chart hints at the science that could be returned (an actual flyby oriented mission would probably include more flybys of the outer moons and possibly Europa). The IPR is the Ice Penetrating Radar and LA is the Laser Altimeter.



Phil Horzempa had some interesting perspectives on the presentations and mission options that I thought I'd pass on:

Some of the info is a re-hash of earlier releases. The new material mostly deals with radiation protection. The Juno Lessons Learned is very interesting, showing how that team dealt with the challenge of radiation on the Juno mission.

As I recall, one of the Congressional appropriations bills directed NASA to present a viable outline for funding the Jupiter Europa Orbiter. In addition, they directed NASA to explore the option of launching JEO in 2018. We must wait to see if that language makes into the conference bill funding NASA.

I feel that a 2018 launch for JEO would be fantastic. It allows JEO to enter Phase A next year, instead of making the JEO team mark time until early 2012 before Phase A begins. In addition, I think that the synergistic observations planned for JEO and JGO, if they are both launched in 2020, are less important to Jovian science than having serial observations. By that, I mean if JEO arrives at the Jupiter system 2 years before JGO, we will have a longer baseline of detailed observations of Jupiter. This is important for the areas of atmospheric and magnetospheric studies. In addition, having a longer baseline increases the chances that one of the Orbiters will still be alive if another major impact occurs on Jupiter.

Recall that these two Orbiters are lifetime limited. They spend about 2 years in orbit around Jupiter, before each enters orbit around their specific moon of interest, i.e., Europa and Ganymede. They will spend about 1 year in orbit around their target moon before each crashes into that moon. There may be short extensions if the Orbiters have surplus fuel.

However, there will be only minimal mission extensions possible, more on the order of months rather than years. They will not be Jovian versions of the Cassini mission which has the capability to extend its mission to a total of about 1 decade.

Therefore, instead of having 2 very capable Orbiters in Jupiter space at the same time, for a total of about 2 - 3 years, we could have those spacecraft follow each other. At about the time that the JEO would be wrapping up its mission, the JGO would be arriving in orbit around Jupiter. In this scenario, we could obtain detailed Jupiter observations for a total of 4 - 5 years.

Resources: http://opfm.jpl.nasa.gov/library/2009opfminstrumentworkshop/

Coming Deluge

Last winter and spring, it was tough to keep up with the news on future planetary planning. In addition to deciding on the destination for the next Flagship mission, there was the saga of the Mars Science Laboratories cost overruns. The last few months have been comparatively quiet. That's about to change.

This current planetary Decadal Survey, as have past ones, is soliciting widespread input from the scientific community on scientific priorities and mission concepts. One key method for input will be white papers written by individual or groups of scientists. This is serious business. Congress and NASA listen to the priorities set by the Decadal Surveys (most of the time, anyway -- MSL as it grew from a modest rover is the exception). Mission proposals that don't address Decadal priorities or that miss fulfilling Decadal goals for specific missions have trouble being selected. The community therefore is taking the process very seriously.

The Decadal Survey committee has set stringent rules for the preparation of white papers -- 12 point font, seven pages, 50MB file size. It appears that they are expecting a deluge, with requests the preparers submit the titles of their white papers ahead of time. Among the topics listed to date are:

• Entry Probe Missions to the Giant Planets
• The Value of Landed Meteorological Investigations on Mars: The Next Advance for Climate Science
• Ganymede science questions and future exploration
• The Case For Ceres

Individual disciplines are organizing their white paper efforts. The Mars community, for example, has its own list of white papers including:

• State of Knowledge of Mars Science and Next Decade Objectives: Executive summary of current state of knowledge and extension to top science objectives realistically achievable during next 10 years
• Strategic Technology Development for Future Mars Missions
• Report from the Mars Geophysical Network Science Analysis Group (MGN-SAG)
• The Value of Landed Meteorological Investigations on Mars: The Next Advance for Climate Science

The last paper is already posted in draft form (http://mepag.jpl.nasa.gov/decadal/SfcMet_17July2009_3.pdf). It probably provides a good example of what to expect. First, the report lays out the case for why the scientific questions are important, why the particular approach is necessary to answer the questions, and then what actions are needed to enable the mission(s) (in this case, include meteorological instruments on all landers and fund technology development for networks of small landers to collect data from dozens of locations on Mars).

I will try to keep on top of the white papers, but expect that the deluge will prove too much to read and summarize. So what you will see here will likely be summaries of what I believe are the key white papers (or at least those that tickle my interest most). If understanding the rational behind planetary exploration interests you and reading about possible missions in interesting, then I suggest that you bookmark the sites listed in this blog entry and make your own selection of which white papers to read.

Resources

Rules for the white papers http://www7.nationalacademies.org/ssb/SSEdecadal_whitepapers.html
Proposed white papers http://www.lpi.usra.edu/decadal/
Mars related white papers http://mepag.jpl.nasa.gov/decadal/index.html
Published white papers http://www8.nationalacademies.org/ssbsurvey/publicview.aspx

ExoMars in Doubt

The latest issue of Aviation Week and Space Technology discusses the continuing travails of ExoMars. It's not clear whether the cooperative arrangement with NASA will bring the mission into line with the maximum budget set by the ESA member nations. In addition, if NASA supplies the entry and descent system (where NASA has real expertise), then the development of this technology as an ESA expertise will not occur. This was one of the selling points of ExoMars, which is funded under the technology development program. A final problem is the the new arrangement with NASA could upset the distribution of contracts among member nations.

The issues are being worked and it appears too soon to put ExoMars on the critical care list. However, the head of ESA is quoted as saying that cancellation is a possibility and that a proposal must be ready by September 1 and ratified by the end of the year.

Editorial Thoughts: The exo-biological exploration of Mars is proving to be expensive with the Mars Science Laboratory coming in at over $2B and ExoMars nearing $1.5B (with instruments paid for separately by member states). I personally think that these missions were proposed for the wrong time period. I believe that several more inexpensive rovers should have been landed first to verify which location(s) would be best for searching for complex organics. Imagine what the reaction will be if either or both missions land in places that look great from orbit but prove unsuitable on the ground. (This is a seperate from the possiblity that the landing sites may in fact prove to be excellent places to search for organics, but that the results prove to be negative.)

Another concern is that these are big, complex missions that stretch the capabilities of both space agencies. I think they should have been placed on the roadmap with several years of technology development before final design and assembly. The proven way to mitigate risk with big missions is to do a substantial portion of the development years before launch, not in the midst of design, manufacture, and testing. (If the Jupiter-Europa mission flies around 2020, it will have had almost 20 years of such study and development before launch. Admitedly, this long is overkill.) My other great fear for both missions has been that development was pushed too quickly and we end up with a technical failure that cripples the mission. I for one am more comfortable with MSL having been delayed two more years to 2011 so that testing can continue another two years.

A Cheaper Way to Measure Venus Surface Composition?

From Bruce Moomaw:

There are two important shared components in both the two Venus Landers proposed by NASA's Venus Science and Technology Definition Team ( http://www.lpi.usra.edu/vexag/reports/venusFlagshipMissionStudy090501.pdf ) and the lighter and cheaper landers in the "SAGE" New Frontiers proposal made by a team led by the Univ. of Colorado's Larry Esposito ( http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38184/1/03-2520.pdf ). Those components are: (1) an X-ray diffractometer/spectrometer to analyze Venusian surface minerals for the first time, and (2) a complicated sample-collection system involving a drill that will bore up samples from 10 cm below the surface and a little airlock to transfer the samples into the room-temperature interior of the armored and insulated lander so that the X-ray instruments can analyze them without our having to use prohibitively expensive revolutionary high-temperature electronics.

That drill/airlock system -- although the Soviet Union used it for X-ray spectral analysis of elements in the Venusian surface on three landers -- is complex, heavy and power-consuming. In Esposito's SAGE landers, it weighs 26 kg and uses 90 watts of power; in the STDT landers, it weighs 35 kg and uses 120 watts. It's also complex enough to be vulnerable to failure (and in fact it did fail on three of the six landers the Soviets equipped with it) -- and if it develops a leak, it could wreck the entire mission by letting Venus' super-hot and high-pressure atmosphere into the lander's interior. Moreover, the X-ray instruments require lengthy sample observation time to get a proper analysis of the less common but scientifically important elements in the sample -- the SAGE lander would spend two hours obtaining adequate X-ray spectra on a single sample, while the STDT landers would take 2.5 hours to analyze each of two surface samples. This naturally requires that the landers be sufficiently armored against Venus's savage surface conditions to last that long, which in turn greatly increases their overall mass and cost.

Is there an alternative? It appears that there is. The Mars Surface Laboratory carries an instrument called "ChemCam", which will actually use a miniature pointable laser to briefly heat points on the Martian surface to incandescence and take visual spectra of the glow to identify even quite scarce elements in just a few seconds. This "laser-induced breakdown spectrometry" ("LIBS") to determine element percentages can also be combined with Raman spectrometry, which makes use of the fact that a small fraction of the laser's light is reflected back at modified frequencies due to the light's interaction with various minerals -- and which, once again, can make its measurements very rapidly. The ChemCam on MSL doesn't have Raman capability, but such a combined instrument is scheduled for the ESA's ExoMars lander.

Preliminary lab tests indicate that combined LIBS/Raman spectrometry will also be completely feasible on Venus, despite the dense and hot CO2 atmosphere that the laser pulse and its reflection must travel through:

http://www.lpi.usra.edu/meetings/venus2009/pdf/2013.pdf

http://www.lpi.usra.edu/meetings/venus2009/pdf/2003.pdf

Such an instrument would completely remove any need for a drill, an airlock, and long sample analysis times -- it could operate by peering through the same windows in the Lander's hull used by its cameras and infrared spectrometers, analyzing patches of surface up to several dozen meters from the lander. It would use much less power than a drill. And the speed of its operation would allow analysis of a dozen or more different spots even if the lander survived only a half-hour or so on the surface.

How comprehensive would a LIBS/Raman analysis be? LIBS can definitely detect all the same elements as X-ray fluorescence spectrometry. And Alian Wang of Washington University tells me that Raman spectrometry, in fact, can unambiguously identify almost all of the same minerals as an X-ray diffractometer except for halide salts, which are very unlikely to be found on Venus. In particular, it can identify amphiboles and other minerals which could be a giveaway to the existence of an ancient liquid-water ocean in Venus' earliest days. Even if Raman spectrometry would miss a few of the minerals detectable by the X-ray technique, the advantages of LIBS/Raman spectrometry -- both in making the lander simpler and cheaper, and in analyzing multiple different places on the Venusian surface -- provide a very strong argument for using it rather than the Rube Goldbergian drill/airlock/long-lived X-ray system. For these reasons the Jet Propulsion Laboratory's 2007 "Planetary Science Summer School" of graduate student interns chose it for the minimum-cost "VEIL" Venus lander they were assigned to design ( http://www.lpi.usra.edu/vexag/nov_2007/presentations/schmidt.pdf ) -- although their version would analyze only one spot on the surface.

One possible problem might be that the chemical reactions of Venus' hot atmosphere and its trace gases with surface minerals might produce a surface rind whose composition would be misleading when it comes to identifying the original minerals in Venus' surface rock. But it might be possible -- as the PSSS interns suggest -- to equip the lander with a grinding wheel on a swivelable arm, such as the two MER rovers have used to scour away coatings on Mars rocks, allowing the lander to analyze virgin rock in at least a few nearby places -- a setup which would still be much simpler and more reliable than a full-fledged coring drill on the lander. This is not to mention the fact that the LIBS pulses, if fired repeatedly at the same location, might be able to do some surface scouring themselves by vaporizing a thin surface coating away.

At any rate, this looks like a highly promising new technique to study a particularly hostile and difficult planet with a minimum of cost combined with a lot of scientific return.

ExoMars Slip Confirmed

BBC has an article that confirms the slip of ExoMars to 2018.

The article also has more detail on the emerging roadmap proposal:

2016: European orbiter to follow up on trace gas discoveries and act as communications relay for future missions. A small surface package might be included. NASA to launch.

2018 (a very favorable launch year): ExoMars with NASA's skycrane entry and descent system and a second MER-class rover (presumably from NASA). These rovers could target any areas of methane or other trace gas emissions. NASA to launch.

2020: A joint ESA-NASA network mission.

Editorial Thoughts: This plan makes sense to me. It leverages past investments in technology and gives the designers of the ExoMars mission the chance to learn from the Mars Science Laboratory (MSL) mission. A precursor network lander in 2016 also makes sense as it allows a test of technologies and instruments for carrying out seismic studies.

It is disappointing, of course, to have ExoMars delayed until 2018.

Resources: BBC article http://news.bbc.co.uk/2/hi/science/nature/8168954.stm