A More Awesome Europa Clipper Proposal

One of NASA’s key advisory committees, the Committee onAstrobiology and Planetary Science (CAPS), is meeting today and tomorrow.  My schedule permits me to listen to just part of the meeting, but I’ve arranged to listen in to two key portions: Today’s update on the Europa Clipper proposal and tomorrow’s presentation on the future Mars roadmap.  (Casey Dreier of the Planetary Society is also blogging on the meeting and covers sessions I couldn’t attend.)

The Europa Clipper is one of three mission concepts to come out of the demise of NASA’s Jupiter Europa Orbiter proposal that would have cost close to $4B.  That sticker shock led the Decadal Survey to recommend that NASA investigate cheaper mission alternatives.  In previous posts, I’ve describe the minimalistic orbiter and a multi-flyby spacecraft (now dubbed, Europa Clipper) and concepts for Europa landers.

Both the orbiter and the Clipper concepts have been estimated to come in at below $2B, meeting the challenge of the Decadal Survey.  The science community has favored the Clipper proposal with its richer instrument set over the orbiter.  (The lander concept is both much more expensive and requires either the orbiter or Clipper mission to scout for safe and interesting landing sites.)  In today’s CAPS meeting, an update to the Clipper concept was provided.

The previous Clipper concept from last spring focused on science best done by a highly capable spacecraft encountering Europa briefly during approximately 30 flybys:

• Characterize the structure of the icy shell with an ice penetrating radar
• Explore the chemistry of the subsurface ocean and the interaction of the ice with Jupiter’s radiation field by examining the composition of materials brought to the surface and subsequently modified with an infrared spectrometer and a neutral mass spectrometer
• Investigate the relationship of surface structure with the ice shell structure and surface composition through imaging with a camera

 

Clipper Science goals (click on image for larger version).  Color coding shows the original goals and the new enhanced goals.  From presentation at CAPS meeting.

This minimalistic instrument set left key goals to a future orbiter mission that would use measurements of the interaction of Jupiter’s magnetic field with the ocean to directly explore the ocean’s characteristics.  (Similar, but less precise measurements than those planned for future Europa missions allowed the Galileo spacecraft to all but prove the existence of Europa’s ocean).  Also left to an orbital mission were the precise gravity measurements that would measure the amplitude of tides in the icy shell that would provide a second validation of the existence of the ocean and also study the tidal forces that restructure the icy shell.

The Clipper definition team listened to a request from the scientific community to enable the magnetic and gravity measurements from a flyby spacecraft.  The new baseline proposal has added a magnetometer, a Langmuir probe (which allows scientists to separate the changes to the magnetic field from Europa’s ocean from transient changes caused by variations of the local plasma field), and a dedicated, gimbaled antenna that can remain pointed at Earth during flybys to allow precise radio measurements.

In parallel, the studies of possible Europa lander missions lead the Clipper definition team to realize that any future landing missions would need high resolution, stereo imaging of possible landing sites.  A thermal imager would also help characterize the size of icy blocks at the surface.  (Small particles the size of gravel would cool fastger following sunset or heat up faster following sunrise much faster than say boulder sized ice chunks.  A lander needs a site with small particles on the surface, not boulders.)  To enable a future landing mission (which may be a decade or two after the Clipper mission eventually flies), the definition team has added a high resolution camera and a thermal imager to the payload.

Unfortunately, these additional instruments and their integration into the spacecraft raised the estimated cost of the Clipper mission from a bit under $2B to approximately $2.2B.  However, the definition team also has begun looking at replacing the previously planned plutonium-based power supply with solar panels.  The early analysis is positive, and if it can be done, the net savings bring the Clipper mission’s cost (not including the launch vehicle) back down to around $2B.

 

Solar-powered version of Clipper concept.  Recon refers to reconnaissance imaging to characterize future possible landing sites.  From presentation at CAPS meeting 

Editorial Thoughts: Wow!!

This will be an awesome mission.  Unfortunately, NASA’s projected budget, which covers the next five years, doesn’t provide funding for this mission.  I can be pessimistic and think that a dedicated Europa mission has been a top priority for over a decade and is no closer to being funded today than in 2000.  However, the quality and cost of this mission gives me hope:  Excellent(!) science without requiring new technology development (as most previous Europa mission proposals did) for a cost well below what the Mars Science Laboratory Curiosity cost (especially when Curiosity’s costs are inflated to the 2015 dollars used for all of the Clipper cost estimates). 

Big science missions in the past often have required a decade or two to go from concept strongly supported by the science community to a funded project.  (Curiosity was one of the rare exceptions.)  We now have a crisp, credible proposal on the table.  Things are tough now, but they have been before (some of you may remember when NASA’s planetary program almost was shut down around 1980).  Tonight, at least, I’m optimistic that Clipper or a descendent of the proposal will be funded, perhaps a decade from now.

In the meantime, if there are any multi-billionaires who read this blog, can you spare a couple for a good cause? 

Not A Bias

Having read a number of forums and the comments on this blog, I know that a number of readers (I as was) were disappointed that the TiME Titan lake lander was not chosen for the next Discovery mission.  It’s now likely that I won’t see another mission to Titan in my lifetime.  Several blogs wondered if NASA had a Mars bias in its mission selection.

Once, in previous career, I was responsible for strategic planning of the product roadmap for a division of a high tech company.   We had to get a new product line out to remain competitive.  At the same time, executive staff of the company was cutting our division’s budget.  The engineering managers planned one set of products for the first budget, and then another for the first budget cut, and one for each subsequent budget cut.  Thanks to the extraordinary effort of the engineers, each plan made creative use of the expected resources to maximize the resources available with each budget. 

Since I started this blog, I have seen NASA’s expected planetary science budget cut again and again.  Each time, NASA’s managers have put together a new roadmap that makes the best use of the new smaller budget. 

When the Discovery program was created, one of the goals was to allow for riskier, more creative missions.  In the first decade, with ten mission starts, a few missions went over budget and one failed outright.  And we had nine brilliant successes.  In the second decade of the program, however, new missions starts have come at a pace of approximately one every five years.  When I was in charge of strategic planning, as budgets were cut, I became more conservative – the risk of failure in the few products possible was too great.

In the press conference announcing the decision for the InSight Mars mission, NASA’s managers stated that the selection of InSight was based on it providing the greatest confidence of a successful mission within the budget cap.  (All three proposals promised great science.)  Using an existing spacecraft design (the Phoenix Mars lander) and with two of three instruments paid for by partner space agencies, InSight was near the budget cap for the Discovery program.  The other two proposed missions, TiME and the CHopper comet mission, required new spacecraft designs and longer flight times, both adding costs. 

I don’t think that a Mars bias is a cause of NASA’s selection of the InSight mission. Rather, I think that the investments in the Mars program enabled a complex mission (as any Mars landing is) within a limited budget.

Perhaps the message in the selection is not that NASA has a bias but that the Discovery budget cap of $425M is too small to allow for compelling missions to other destinations.  If this is true, the proposal to raise the cap to $500M in the Decadal Survey report may enable new targets for the Discovery program.  However, if new Discovery missions remain twice in a decade events, then I think the natural tendency will be to be conservative with mission selections.  (See this article from Nature or this blog entry for more on the debate on whether Discovery mission selections have become more conservative.)

To enable a well-balanced program of missions to many solar system destinations, NASA’s needs increased fiscal support from the President’s office and Congress.  Instead, the immediate prospect is for possible further cuts as part of sweeping automatic cuts to the federal budget.  (See this blog post atthe Planetary Society’s webpage for the full gory details.) 

Whatever happens, I am confident that NASA’s planetary managers will continue to make best use of the funding made available.  To have the kind of program that I and I think most of my readers would like to see, NASA needs additional funding for planetary research.  NASA’s managers cannot lobby Congress for additional funding.  If you are an American citizen, however, you can.  I encourage you to contact Congress on your own or to join with the PlanetarySociety in its efforts to gain increases in NASA’s planetary exploration budget.

Organics and ExoMars

The ExoMars Entry, Descent, and Landing Demonstator Module.  Credit and Copyright ESA.

This week’s Science journal included an article on the challenges facing the Curiosity rover in its hunt for organic molecules on Mars.  (Unfortunately, the article is available by subscription only.)  Complex organic molecules would be a clue that Mars may have once harbored life or at least the conditions that allowed for complex pre-biotic chemistry to occur.  Three spacecraft, the two Viking landers and the Phoenix lander, have so far tested Martian soil for organic molecules and come up with negative results.  (Although some argue that the natures of the failures suggest instrument limitations rather than the lack of complex organics.)  The failure to find organic molecules suggests that processes on Mars are destroying organic molecules since the surface is subject to a steady rain of meteorites that contain less complex organic molecules.  Per the article, researchers have identified three mechanisms that may be destroying organic molecules at and near the surface of Mars: oxidizers in the soil including the perchlorate salts found by Phoenix, ultraviolet radiation, and cosmic rays.  The article states, “With decomposed perchlorates, cosmic rays, and ultraviolet radiation ganging up on Martian organic matter, Curiosity's chances of finding it when it scoops up its first soil samples are looking slim. And ‘if we find [soil] organics, it almost certainly will have nothing to do with life,’ says astrobiologist Christopher McKay of NASA Ames. The most likely organics in soils would be those of cosmic dust because they are continually resupplied, so detecting organics is not detecting life,’ he says.”

One of the challenges facing Curiosity’s hunt for organic molecules is that its drill can sample only 10 centimeters into a rock or into the regolith, not deep enough to avoid the agents that destroy organic molecules.  ESA’s ExoMars rover has been designed to sample up to two meters beneath the surface, below the reach of surface destroyers of organic molecules.

ESA has continued to redesign the ExoMars mission with Russia as its only partner after the U.S. declined to participate.  European financing for the total bill remains a challenge and the final resolution isn’t expected until this Fall.

ESA recently published a newsletter on the current state of the mission definition.  The 2016 Orbiter will carry two European instruments – the NOMAD spectrometer to map trace gases and a high resolution stereo color camera.  Russia will supply two additional instruments for the orbiter – the Atmospheric Chemistry Suite that will map the structure of the atmosphere (the ESA publication doesn’t discuss why a chemistry instrument will map structure, which typically is measured in terms of temperature and pressure) and a neutron detection instrument to refine measurements of near surface water ice.

A major goal of the 2016 mission has been to test European technologies for landing mid-sized payloads such as geophysical stations.  (The seven minutes of terror to get a payload to the surface of Mars exists for any space agency wanting to land on Mars.  Developing and proving a landing capability enables future lower cost missions, much as the demonstration of the Phoenix system enabled the recent selection of the InSight mission.)  At one time, there was discussion of including a Russian radioisotope power supply to enable a long-lived lander.  Now the plan has reverted to a battery powered lander with a short (few days at most) lifetime.  

Russia will also supply two new instruments for the 2018 rover mission – an infrared spectrometer and a neutron spectrometer.  (Russia also supplied a neutron spectrometer for NASA’s Curiosity rover to search for near surface hydrogen deposits that would indicate the presence of H₂O.)

The brief newsletter also talks about a surface science platform in addition to the ExoMars rover.  It’s unclear what this might be, although a geophysical station might be a possibility.  The supporting web site simply says, “the two space agencies have agreed to send a large capsule to Mars with a surface science platform and a rover carrying both European and Russian instruments. The two science stations will operate in parallel.”  (At one time, before the first descope to reduce costs, the ExoMars mission included a sophisticated geophysical station in addition to the rover.)

Russia will have the leading role in delivering the rover and science station to the surface: “the descent and surface modules will be developed by Roscosmos in cooperation with ESA.” 

Editorial Thoughts: First, I hope that enlightened selection of sampling locations (with maybe a large helping of luck) will enable the Curiosity rover to find the organic molecules its instrument suite is designed to find.  A success would enhance chances for funding a robust future Mars program, while a fourth strike won’t be helpful.

Given the challenges of finding intact organic molecules – assuming they exist – I remain a fan of the ExoMars rover mission and hope it secures it European funding this fall.  I am concerned about the 2018 landing mission becoming too complex – ESA has never done a rover mission and Russia has never successfully landed a mission on Mars.  Now the mission has become more complex with a surface science station.  NASA hit a home run with the Curiosity landing and subsequent rover operations, but that was after a string of six successful, and simpler, landings.  ESA’s track record for planetary missions has been excellent, providing confidence for the ESA 2016 orbiter and 2018 rover.  Russia, after the failure of the Phobus-GRUNT mission last year, reportedly is in the process of reforming its design processes.  Landing a good-sized rover and surface station on your first try at a Martian landing in over 40 years is an ambitious goal.  (A recent article in the Guardian makes the same point, but less diplomatically.  Until I hear otherwise, I presume that ESA and RSA are aware of the challenges and taking appropriate steps.)

My fingers are crossed that the budgetary and technical stars align for ExoMars.  The search for signs of pre- or actual biotic organics on the second most Earth-like planet in the solar system is important to the future of planetary exploration.

It's InSight

Artist rendition of the proposed InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) Lander. InSight is based on the proven Phoenix Mars spacecraft and lander design with state-of-the-art avionics from the Mars Reconnaissance Orbiter and Gravity Recovery and Interior Laboratory missions. Credit: JPL/NASA  From the press release.

NASA announced its selection for the next Discovery mission, the InSight geophysical mission to launch to Mars in 2016.

I know that many of my readers, and I, were hoping that the Titan TiME mission would be selected.  For me, the science of the three candidate missions were all excellent.  However, orbital mechanics meant that this would be the last chance to launch a Titan lake lander that could send its finding directly to Earth without a relay craft.  It's possible to fly a Titan lake lander in the next couple of decades, but the cost of the mission would be higher because of the need for a relay craft.  If the minimal relay is flown, the mission on the lake will last at most hours before the craft moves out of sight of the lakes.  A Saturn or Titan orbiter could enable a mission that could last years, but comes with a substantial cost (but could also do considerable science).  Either the Chopper comet lander mission or InSight could have flown at a number of launch opportunities (although a different comet likely would have to be selected for Chopper).

NASA's managers stated in the press conference that all three candidate missions had equivalent science, but InSight provided the lowest technical and budgetary risk.  That's not surprising since the instruments are mature and the lander itself is a near copy of the successful Mars Phoenix lander.

With the selection of InSight, NASA will need to seek another mission to flight test its new Advanced Stirling Radioisotope Generator (ASRG) that represents its next generation technology to power spacecraft with plutonium.  NASA has announced that ASRG's will be available for the next round of New Frontiers mission selection.  I've not heard whether or not ASRG's will be candidate for the next Discovery mission to be selected in approximately five years.

NASA's renewed focus on Mars missions provides a compelling reason for the InSight mission.  Missions over the last twenty years have greatly deepened our understanding of Mars, and several missions continue their explorations.  The Curiosity rover's mission is just beginning.  Starting in 2018, NASA plans to begin a new series of missions.  InSight neatly plugs a gap in our exploration of Mars -- the deep interior.  In many ways, the surface geology and atmospheric chemistry of any planet are consequences of the composition, structure, and activity of the deep interior.  With InSight, we can begin to link the interior, surface, and atmosphere in new ways.

For more information on the InSight mission, check out these links:

InSight webpage
Summaries I wrote for this blog
     InSight Mission Proposal
     Mars InSight Proposal – Implementation and Science
Presentation on the science of geophysical missions to Mars

Press release follows:

New NASA Mission To Take First Look Deep Inside Mars
20 Aug 2012
(Source: NASA / JPL)

PASADENA, Calif. -- NASA has selected a new mission, set to launch in 2016, that will take the first look into the deep interior of Mars to see why the Red Planet evolved so differently from Earth as one of our solar system's rocky planets.

The new mission, named InSight, will place instruments on the Martian surface to investigate whether the core of Mars is solid or liquid like Earth's, and why Mars' crust is not divided into tectonic plates that drift like Earth's. Detailed knowledge of the interior of Mars in comparison to Earth will help scientists understand better how terrestrial planets form and evolve.

"The exploration of Mars is a top priority for NASA, and the selection of InSight ensures we will continue to unlock the mysteries of the Red Planet and lay the groundwork for a future human mission there," NASA Administrator Charles Bolden said. "The recent successful landing of the Curiosity rover has galvanized public interest in space exploration and today's announcement makes clear there are more exciting Mars missions to come."

InSight will be led by W. Bruce Banerdt at NASA's Jet Propulsion Laboratory in Pasadena, Calif. InSight's science team includes U.S. and international co-investigators from universities, industry and government agencies. The French space agency Centre National d'Etudes Spatiales, or CNES, and the German Aerospace Center are contributing instruments to InSight, which is scheduled to land on Mars in September 2016 to begin its two-year scientific mission.

InSight is the 12th selection in NASA's series of Discovery-class missions. Created in 1992, the Discovery Program sponsors frequent, cost-capped solar system exploration missions with highly focused scientific goals. NASA requested Discovery mission proposals in June 2010 and received 28. InSight was one of three proposed missions selected in May 2011 for funding to conduct preliminary design studies and analyses. The other two proposals were for missions to a comet and Saturn's moon Titan.

InSight builds on spacecraft technology used in NASA's highly successful Phoenix lander mission, which was launched to the Red Planet in 2007 and determined water existed near the surface in the Martian polar regions. By incorporating proven systems in the mission, the InSight team demonstrated that the mission concept was low-risk and could stay within the cost-constrained budget of Discovery missions. The cost of the mission, excluding the launch vehicle and related services, is capped at $425 million in 2010 dollars.

"Our Discovery Program enables scientists to use innovative approaches to answering fundamental questions about our solar system in the lowest cost mission category," said John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters. "InSight will get to the 'core' of the nature of the interior and structure of Mars, well below the observations we've been able to make from orbit or the surface."

InSight will carry four instruments. JPL will provide an onboard geodetic instrument to determine the planet's rotation axis and a robotic arm and two cameras used to deploy and monitor instruments on the Martian surface. CNES is leading an international consortium that is building an instrument to measure seismic waves traveling through the planet's interior. The German Aerospace Center is building a subsurface heat probe to measure the flow of heat from the interior.

JPL provides project management for NASA's Science Mission Directorate. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Discovery Program for the agency's Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver will build the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.

For more information about InSight, visit: http://insight.jpl.nasa.gov.

For more information about the Discovery Program, visit: http://discovery.nasa.gov.

For information about NASA and agency programs, visit: http://www.nasa.gov.

Updates Before Curiosity's Landing

The news for the next couple of weeks at least will be dominated by news of the Mars Science Laboratory’s landing and first days on Mars.  I will be in the field Sunday night without access to the internet and so will have to learn of its fate Monday morning.  God speed, Curiosity!

With the focus on Curiosity, I suspect that few of you will be interested in news on future missions for a couple of weeks.  So in today’s post, I will catch up on a lot of stories that I haven’t had time to cover in the past month or so.  I’ll start with news that will affect the potential flight of real hardware and will close with more general policy news.

An in-depth overview (if 52 pages can be considered an overview) is available at no charge from thejournal Space Science Reviews.  Scroll through the recently posted papers for a selection of other open access papers covering several instruments.   

The journal Nature’s website has an article on the Curiosity landingthat includes a nice illustration of how much tighter Curiosity’s landing zone will be than previous missions with the area of the city of London to provide scale.  

The key future planetary mission news of August will be the expected selection of the next NASA Discovery mission and the delivery of the proposed future NASA roadmap.  NASA posted a one sentence notice about a week ago that the announcement of which mission it would pick for the next Discovery mission would come in August.  I expect that the announcement will come in the second half of the month so as to not conflict with the news from Curiosity’s landing.  The NASA roadmap will come from the panel NASA established last winter that will cover the program from 2018 to the early 2030’s (see this summary at SpacePolitics.com).  It’s unclear what may be disclosed publicly and when.  What will be possible will be tightly tied to NASA’s proposed 2014 budget, so we may not learn the details until next winter.

A lecture by the Discovery proposal TiME to Titan by the Principle Investigator, Ellen Stofan, is available from this link.  

The European and Russian space agencies continue to make progress with the definition and development of their joint ExoMars mission.  So far as I know, Europe’s decision on whether or not to proceed with the mission is still planned for this fall and depends on finding sufficient funding to close the gap between what member nations have committed and what is needed.  MarsDaily.com reprinted an article from Voice of Russia that provides a list of Russian contributions.  It’s not clear from the article whether these are a list of possible contributions or those that both agencies have agreed to.  The article states that the 2016 orbiter will carry several Russian instruments.  No mention is made of previously discussed Russian provided small landers.  The 2018 rover mission apparently will include a Russian-provided geophysical station that will be delivered with the rover to the Martian surface. 

China has announced that its first lunar lander will arrive on the surface of the moon in the second of 2013 (see here).    The mission is expected to survive for atleast three months on the surface.  China's eventual goal is to return a lunar sample to Earth.  

ESA and NASA have both released their announcements of opportunity for the science community to propose instruments for ESA’s JUICE mission to the icy moons of Jupiter.  (NASA’s contribution to the mission will be $100M, or about 10% of what I recall will be the total investment by ESA and individual European nations for instrument development.)  ESA and Russia are also discussing possible Russian contributions to the mission.

Spectrometers on the Mars Express and Mars Reconnaissance Orbiters has found rocks exhumed from up to several kilometers below the surface of Mars by impactors show that water was present for extended periods below the surface (see article here).  Geologists debate whether the water at the surface of Mars was present for extended or only short periods of time. I wonder if these rocks that are now on the surface might become the focus of a future rover mission to explore whether the ancient depths of Mars might have provided a habitat for life?  

The B612 Foundation has announced plans to raise several hundred mission dollars to launch a space telescope that will seek to find 90% of the near Earth asteroids 100 m and larger in diameter and 50% of those as small as 30 m for an expected total of 500,000 new asteroid discoveries..  If the required funds are acquired, the spacecraft would orbit near the orbit of Venus to look outward toward Earth’s orbit.   

And now for some policy news.  Pamela Gay at StarStryder.com discusses how cuts in NASA’s budgets to fund researchers and public outreach are affecting her and other researchers.  (Full disclosure: A portion of my research funding comes from NASA, and I also worry about future funding from both NASA and my other funding agencies.)  She writes, “NASA cut backs could cut me, and deeply hurt my team unless I find other means of funding us. With the National Science Foundation also cutting back… The traditional funding mechanisms aren’t a modern day solution.”  Dr. Gay goes on to discuss a new Indiegogo campaign to raise funds for researchers through crowd sourcing.  If you would like to make a difference to planetary research and can make a contribution (or are just curious) check out their website.  For those of you who are not researchers, you may not know that a few tens of thousands of dollars can fund a graduate student for a year, and less than $100K can fund many small focused studies.  The group currently is looking to raise $75K to fund startup costs. 

And finally, NASA’s Small Body Analysis Group (SBAG) has published its findings from its meeting last May.  Their comments on the changing nature of the Discovery program dove tail an opinion piece is this week’s Nature journal (subscription required).  In Nature, Daniel N. Baker (University of Colorado, Boulder and previously a laboratory director at NASA's Goddard Space Flight Center) urges that NASA rebalance it planetary and Earth science programs to provide a greater emphasis on smaller Principle Investigator missions such as the planetary Discovery and New Frontiers and the Earth science Venture missions.  He writes that, “Increasingly, NASA's focus is on big projects that promise to return tremendous science benefits. But these programmes absorb most of the available funding for space research. They shift resources away from efficient and effective principal investigators (PIs) at universities, an approach in which a single person is responsible to NASA for the success of a mission, and towards bureaucratic NASA centres. This is the wrong direction for space research, especially in a time of scarce funding… Universities have been a fertile training ground for thousands of space engineers and researchers, who have learned to be creative while sticking to budgets and schedules… [Yet,] University labs are being driven out of business,” and losing the capacity to develop PI-led missions.

Editorial Note:  In the past, NASA’s planetary budget was large enough to support vigorous programs of larger, agency-led missions as well as smaller PI-led missions.  Now NASA and the scientific community it supports will have to decide on what the new balance should be.  Perhaps creative solutions may be possible.  For example, NASA might develop a new series of smaller, Opportunity-class Mars rovers but let potential PI’s compete to define the payload and landing site.

What follows are the comments from SBAG website:

The Discovery program has substantially collapsed as a source of planetary missions. In its first decade (1992–2001), ten missions were selected for launch. During its second decade (2002–2011), only one was selected.  Implementation of the planetary decadal survey recommendation for a 24-month cadence of Discovery AOs is imperative.

Merging the Mars Scout program with Discovery puts yet further pressure on this program. Restoring the Discovery program to two selections for launch per call is very important to the future of American solar system exploration.

It is noted that one new selection is pending as of this date. The next planned Discovery opportunity currently delayed until 2015. Within the resources it has for missions and mission planning activities, NASA and the Planetary Science Division should work to provide a Discovery opportunity sooner than 2015, as advocated by the decadal survey.

DISCOVERY HISTORY (Initial selections: NEAR, Pathfinder)

AO Date      Missions (and year selected)
1994:          Lunar Prospector, Stardust (1995)
1996:          Genesis, CONTOUR  (1997)
1998:          Deep Impact, MESSENGER (1999)
2000:          Kepler, Dawn (2001)
2002:          *No AO Released*
2004:          *No Mission Selection*
2006:          GRAIL (2007)
2008:          *No AO Released*
2010:          Not yet selected (selection expected in 2012)