ESA Approves Funds for Joint Mars Missions with NASA

2016 Trace Gas Orbiter releasing the demonstration lander

Space New reports that ESA has cleared funding to continue work on the 2016 joint Mars mission with NASA.  In that mission, ESA will provide the orbiter and a demonstration lander, while NASA will provide the launch and fund the instruments.  ESA's budgetary rules had required it to issue a stop work order and seek approval for a new program following changes in NASA's ability to fund the joint 2016 and 2018 missions, which were a single program within ESA.

It appears that this approval also covers the joint 2018 rover mission, although the article is not totally clear on that point.  The rover mission is still in the early re-definition phase following the Decadal Survey recommendation that NASA's contribution to the mission be capped.  That meant that the previous plan where each agency would supply its own orbiter was no longer feasible.

See this post for a description of the Trace Gas Orbiter instruments.

Mars Science Laboratory Apparently OK

In a follow up to a report that the backshell for the Mars Science Laboratory may have been damaged, Aviation Week and Space Technology reports that apparently there is no damage and provides more detail on the mishap.

Asteroid Sample Return Mission Selected

NASA announced the selection of the OSIRIS-REx near-Earth asteroid sample return for the next New Frontiers mission, beating out a Venus lander and a lunar sample return mission.  Bruce Moomaw wrote about the OSIRIS-REx mission for this blog, and his description can be found here.  There are also articles at Space News and at the Planetary Society's blog site.  NASA press release site also includes a video (which I can't watch with my current slow internet while I'm traveling): http://www.nasa.gov/topics/solarsystem/features/osiris-rex.html

With the two Japanese Hayabusa sample return missions (one completed and another in development), this means we'll have samples from three near-Earth asteroids.  ESA is also considering its own near-Earth asteroid sample return, Marco Polo.

The press release itself is copied below.  And congratulations to the winning team which submitted versions of this mission at least twice and I think perhaps three times.

May 25, 2011

Dwayne C. Brown 
Headquarters, Washington 
202-358-1726 
dwayne.c.brown@nasa.gov 

RELEASE: 11-163

NASA TO LAUNCH NEW SCIENCE MISSION TO ASTEROID IN 2016

WASHINGTON -- NASA will launch a spacecraft to an asteroid in 2016 and 
use a robotic arm to pluck samples that could better explain our 
solar system's formation and how life began. The mission, called 
Origins-Spectral Interpretation-Resource 
Identification-Security-Regolith Explorer, or OSIRIS-REx, will be the 
first U.S. mission to carry samples from an asteroid back to Earth. 

"This is a critical step in meeting the objectives outlined by 
President Obama to extend our reach beyond low-Earth orbit and 
explore into deep space," said NASA Administrator Charlie Bolden. 
"It's robotic missions like these that will pave the way for future 
human space missions to an asteroid and other deep space 
destinations." 

NASA selected OSIRIS-REx after reviewing three concept study reports 
for new scientific missions, which also included a sample return 
mission from the far side of the moon and a mission to the surface of 
Venus. 

Asteroids are leftovers formed from the cloud of gas and dust -- the 
solar nebula -- that collapsed to form our sun and the planets about 
4.5 billion years ago. As such, they contain the original material 
from the solar nebula, which can tell us about the conditions of our 
solar system's birth. 

After traveling four years, OSIRIS-REx will approach the primitive, 
near Earth asteroid designated 1999 RQ36 in 2020. Once within three 
miles of the asteroid, the spacecraft will begin six months of 
comprehensive surface mapping. The science team then will pick a 
location from where the spacecraft's arm will take a sample. The 
spacecraft gradually will move closer to the site, and the arm will 
extend to collect more than two ounces of material for return to 
Earth in 2023. The mission, excluding the launch vehicle, is expected 
to cost approximately $800 million. 

The sample will be stored in a capsule that will land at Utah's Test 
and Training Range in 2023. The capsule's design will be similar to 
that used by NASA's Stardust spacecraft, which returned the world's 
first comet particles from comet Wild 2 in 2006. The OSIRIS-REx 
sample capsule will be taken to NASA's Johnson Space Center in 
Houston. The material will be removed and delivered to a dedicated 
research facility following stringent planetary protection protocol. 
Precise analysis will be performed that cannot be duplicated by 
spacecraft-based instruments. 

RQ36 is approximately 1,900 feet in diameter or roughly the size of 
five football fields. The asteroid, little altered over time, is 
likely to represent a snapshot of our solar system's infancy. The 
asteroid also is likely rich in carbon, a key element in the organic 
molecules necessary for life. Organic molecules have been found in 
meteorite and comet samples, indicating some of life's ingredients 
can be created in space. Scientists want to see if they also are 
present on RQ36. 

"This asteroid is a time capsule from the birth of our solar system 
and ushers in a new era of planetary exploration," said Jim Green, 
director, NASA's Planetary Science Division in Washington. "The 
knowledge from the mission also will help us to develop methods to 
better track the orbits of asteroids." 

The mission will accurately measure the "Yarkovsky effect" for the 
first time. The effect is a small push caused by the sun on an 
asteroid, as it absorbs sunlight and re-emits that energy as heat. 
The small push adds up over time, but it is uneven due to an 
asteroid's shape, wobble, surface composition and rotation. For 
scientists to predict an Earth-approaching asteroid's path, they must 
understand how the effect will change its orbit. OSIRIS-REx will help 
refine RQ36's orbit to ascertain its trajectory and devise future 
strategies to mitigate possible Earth impacts from celestial objects. 

Michael Drake of the University of Arizona in Tucson is the mission's 
principal investigator. NASA's Goddard Space Flight Center in 
Greenbelt, Md., will provide overall mission management, systems 
engineering, and safety and mission assurance. Lockheed Martin Space 
Systems in Denver will build the spacecraft. The OSIRIS-REx payload 
includes instruments from the University of Arizona, Goddard, Arizona 
State University in Tempe and the Canadian Space Agency. NASA's Ames 
Research Center at Moffett Field, Calif., the Langley Research Center 
in Hampton Va., and the Jet Propulsion Laboratory in Pasadena, 
Calif., also are involved. The science team is composed of numerous 
researchers from universities, private and government agencies. 

This is the third mission in NASA's New Frontiers Program. The first, 
New Horizons, was launched in 2006. It will fly by the Pluto-Charon 
system in July 2015, then target another Kuiper Belt object for 
study. The second mission, Juno, will launch in August to become the 
first spacecraft to orbit Jupiter from pole to pole and study the 
giant planet's atmosphere and interior. NASA's Marshall Space Flight 
Center in Huntsville, Ala., manages New Frontiers for the agency's 
Science Mission Directorate in Washington. 

Where Should MSL Land?

Ryan Anderson has a nice summary of the current views on the four candidate Mars Science Laboratory landing sites at his blog.  Science has nice images of the landing sites.  We should find out early this summer which site NASA will select.
 
Editorial Thoughts: What a great set of choices!  If I were really pressed, I would probably go with Mawrth because it likely has the oldest materials available for study.  However, any of these sites would be great to explore.

Mars Science Laboratory May Have Been Damaged

Aviation Week and Space Technology reports that the backshell for the Mars Science Laboratory may have been damaged.  If it was, this may put the launch this year at risk.

Reducing Costs of an Europa Orbiter

Prior to the announcement of the Discovery candidate missions, I had been exploring options to explore th outer planets within the new fiscally constrained environment.  Previous posts had looked at options for Discovery missions.  The inclusion of the Titan TiME lake probe makes it more likely that at least some Discovery outer planet missions may be possible and scientifically competitive.

Today, I want to consider options for a much reduced cost Europa orbiter.  I'll start by stating that I don't know how much costs can be reduced.  ESA's proposed Jupiter Ganymede Orbiter would approximately fit within the new proposed New Frontiers budgets planned for the next competition.  (Direct cost comparisons using public information are difficult between ESA and NASA missions, because they use different accounting rules and the exchange rates may not reflect actual purchasing power.)  JGO, however, doesn't face the extreme radiation that an equivalent Europa mission would face.  The costs of radiation hardened electronics and additional shielding certainly would add substantial costs if the same mission were flown to Europa.  NASA's Jupiter Europa Orbiter study group estimated that the cost of a minimal mission would be approximately FY07 $2.1B (although the report didn't specify the exact set of options behind that estimate).  However, the same group also estimated that the cost of the full JEO mission would be FY07 $2.7B or $3.8B in real year costs.  The Decadal Survey estimated the real year JEO costs would be $4.7B, putting the FY07 $2.1B minimum cost estimate in doubt.

This post, therefore, may be an exercise if futility -- there may be no way to orbit Europa for less than a major Flagship cost in an era where Flagship missions don't appear affordable.  From the meetings I've listened to, however, the Europa science community would like to see how low the cost of the minimally justifiable mission could be driven.  I'll explore two related areas where costs might be reduced: limiting the science goals and shortening the time in Europa orbit.

The JEO study team carefully laid out priorities for studying Europa and for the instruments supporting each study.  The phasing of the mission timeline also corresponded to those priorities.  One approach to defining a minimally acceptable mission would be to pare back the priorities to a minimum core, which also reduces instruments and potentially time needed in orbit.  Because the radiation damage is cumulative over time, the shorter the orbital mission, the lower the cost to design a radiation hardened spacecraft and instruments.

The JEO study team identified four overall goals (for simplicity, I won't reproduce the list of sub goals) and core supporting instruments in priority order:

1. "Ocean -- Characterize the extent of the ocean and its relation to the deeper interior" -- Laser altimeter and radio science for gravity measurements
2. "Ice -- Characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange" -- Ice penetrating radar 
3. "Chemistry -- Determine global surface compositions and chemistry, especially as related to habitability" -- Visible-IR Imaging Spectrometer, UV Spectrometer, Ion and Neutral Mass Spectrometer
4. "Geology -- Understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ exploration" -- Thermal Instrument, Narrow Angle Camera, Wide Angle Camera and Medium Angle Camera"

In addition to these instruments were a magnetometer and a plasma instrument to characterize the induced Europan magnetosphere as a method to explore the ocean and the coupling of the surface with Jupiter's magnetosphere.

The relationship between instruments and goals is more complicated than that I presented here (which comes from the summary charts in the front of the report).  The exhaustive detail charts in the body of the report shows that several instruments could contribute multiple goals.  The wide-angle camera, for example, would contribute to the ice, chemistry, and geology studies.  The JEO report authors concluded that the minimum instrument set should be:

• Radio Science
• Laser Altimeter
• Near-IR spectrometer (less capable than the Visible-IR Imaging Spectrometer planned for JEO)
• Ice penetrating radar
• Wide and medium cameras
• Magnetometers
• Plasma instrument

A new proposal for a pared down mission might further reduce this list and probably would recommend less complex instruments than envisioned for JEO.  If the new proposal were to address just the ocean and ice goals, the cameras and spectrometer might be dropped.  Those instruments also require the high data rates, and dropping them would reduce power and communications requirements.

The second place to look for mission savings would be in the length of time spent in orbit around Europa.  The JEO study members identified several distinct mission campaigns, with earlier campaigns addressing higher priority goals:

Europa Campaign 1, Global Framework (200 km orbit, ~28 days): First order characterization of the ocean and ice shell through studies of tidal deformation (laser instrument), gravity (radio science), and magnetic field (magnetometers and plasma instrument).  Global stereo and color maps (wide angle camera).  Identification of shallow water and deep ocean search (ice penetrating radar).  Measurements of surface composition (Visible-IR Imaging Spectrometer operating in a profiling mode where the 1-D location directly beneath the spacecraft would be measured in contrast to the mapping mode where 2-D images are produced)

Europa Campaign 2, Regional Processes (100 km orbit, ~43 days): The studies from campaign 1 continue, and higher resolution studies at regional scales are added.

During these first two campaigns some targeted studies using the full instrument suite were planned.  Two campaigns, however, were planned for higher resolution studies, Europa Campaign 3: Targeted Processes (1-2 months), and Campaign 4: Focused Studies (~5 months).  These additional campaigns would also provide time for more orbits that would narrow the spacing between ground tracks for the laser altimeter and ice penetrating radar.

The JEO authors listed 3.5 months as the minimally acceptable mission, but perhaps in the new budget realities just the 28 days of Campaign 1 or an additional month or two for Campaign 2 would constitute the minimum mission.

You can download the JEO report at http://opfm.jpl.nasa.gov/library/

Editorial Thoughts: Defining a new lower cost Europa mission will be a multifaceted approach where every possible cut in goals may reduce costs in multiple areas.  (For simplicity, and because I'm not a spacecraft engineer, I didn't discuss the power or data requirements that would also be intertwined with all these elements.)  The final proposal has to do more than meet a budget figure, however, it must also provide compelling science equal to that which other missions for the same budget might provide.  If a mission were defined that could fit within the New Frontiers budget but carried only a laser altimeter and radio science, would this be a compelling use of >$1B of NASA's budget when the same amount might return a sample from a comet or put a lander on Venus?  I don't know the answer, but I expect that this question will be in the minds of the team that relooks at an Europa orbiter.

One Decadal Survey White Paper (A budget phasing approach to Europa Jupiter System Mission Science) by David E. Smith of the Goddard Spaceflight Center recommended splitting the JEO goals across three smaller missions.  The total cost for implementing the JEO science was expected to be about the same as for JEO, but the costs could be spread over a number of missions.  My impression is that the goal of the paper was to point out that there were alternative approaches to exploring Europa rather than to present a rigorous analysis of particular mission concepts that would provide solid feasibility and cost estimates that would form the basis for a mission proposal. Rather the paper pointed to the direction of reducing mission goals as the way to reduce costs for individual mission.  In the current budget constrained environment, my feeling is that the Europa community will get at most one scaled back mission, and not a series.

My sense in having read many reports (but having no expertise, so take this with a large grain of salt) is that the minimum mission that would be scientifically compelling for the cost could focus on only the ocean and ice priorities but with some attention to the chemistry and geology goals.  I speculate that a minimum mission might consist of:

• 2 months in orbit, 200 km
• Ice penetrating radar
• Wide-angle color camera
• Profiling near IR Spectrometer
• Magnetometer
• Laser altimeter
• Radio science

Even within this limited mission scope, there is considerable room for examining options.  An European mission study (IAC-04-Q.2.a.02 SYSTEM CONCEPTS AND ENABLING TECHNOLOGIES FOR AN ESA LOW-COST MISSION TO JUPITER/EUROPA) estimated the mass of this instrument set at 18 kg while the equivalent JEO instruments would have been 75 kg.  Eighteen kilograms seems like it might be on the low side, but there may well be room to reduce costs by lowering instrument capabilities.

The European study also showed that there may be many ways to skin the Europa orbiter cat.  It recommended a truly minimalistic solar powered Europa orbiter that used a second relay craft in orbit around Jupiter to send the data back to Earth.  I expect that we'll see some creativity as the science community tries to find a way to enable an Europa orbiter.

Junocam

The upcoming Juno Jupiter orbiter will include a camera that was originally intended for use as a public outreach tool.  The engineers at Malin Space Science Systems, which designed the Junocam camera, have enhanced it to include some scientific capabilities, including a near-IR band to map methane abundance.  You can read their press release at http://www.msss.com/news/index.php?id=24.

Juno will also carry an infrared imager provided by the Italian Space Agency: (http://juno.wisc.edu/spacecraft_instruments_JIRAM.html) and an ultraviolet imaging spectrometer.

Editorial Thoughts: Juno is an excellent mission on all accounts and will greatly deepen our understanding of Jupiter's origins, structure, atmosphere, and magnetosphere.  It should also, thanks to Junocam, provide stunning images of Jupiter's cloud decks as the spacecraft passes close to the planet.  The armchair explorer in me is hoping for a close up of the Great Red Spot.

Current Summaries of Discovery Candidate Missions

Jim Adams, Deputy Director for NASA's Planetary Science Division made a presentation on May 10 with summaries of the three recently selected Discovery mission candidates.  Unlike much of the information available on these proposals which is often two or more years old, these summaries should reflect the current state of the proposals. 

You can read the entire presentation at http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf.  The one slide summaries of the missions begin on slide 12.  Double click on the images to read the full slides.

Geophysical Monitoring Station (GEMS)

Over the last few days, since the announcement of the Discovery mission candidates, I've done some sleuthing on the internet to find out more about the mission candidates.  (Thank you for tips in the comments and on the Unmanned Spaceflight Forum.)  I've found some abstracts and presentations on the candidate missions.

Before I present what I found, I want to say that I am delighted by the complexity of the missions that made the final list.  A Mars lander, a sophisticated comet orbiter and multiple lander, and a Titan lake probe.  It appears that effectively increasing the Discovery mission budget by no longer counting the launch vehicle against the Principal Investigator's budget allows sophisticated missions within the Discovery program.  Imagine four to five of these missions flying within a decade (plus two New Frontiers missions and with any luck, the Mars 2016 Trace Gas Orbiter and a joint ESA-NASA Mars rover mission).  I still hope for an outer planets small flagship mission, but even without it, this is an exciting program.

With this post, I'll present the Mars GEMS mission and move on to the other Discovery candidates with the following posts.

An artist's concept portrays the proposed Geophysical Monitoring Station mission for studying the deep interior of Mars. Image Credit: NASA/JPL-Caltech

Geophysical Monitoring Station (GEMS): A Discovery-Class Mission to Explore the Interior of Mars

American Geophysical Union, Fall Meeting 2010, abstract #DI43A-1938  http://adsabs.harvard.edu/abs/2010AGUFMDI43A1938B

Banerdt, B.; Cox, Z. N.; Seybold, C.; Warwick, R.; Barry, S.; Hudson, T. L.; Hurst, K. J.;Kobie, B.; Sklyanskiy, E.

"The GEophysical Monitoring Station (GEMS) is a proposed Discovery-class mission designed to fill a longstanding gap in the scientific exploration of the solar system by performing, for the first time, an in-situ investigation of the interior ofMars. This mission would provide unique and critical information about the fundamental processes governing the initial accretion of the planet, the formation and differentiation of its core and crust, and the subsequent evolution of the interior. The scientific goals of GEMS are to understand the formation and evolution of terrestrial planets through investigation of the interior structure and processes of Mars and to determine its present level of tectonic activity and impact flux. A straightforward set of scientific objectives address these goals: 1) Determine the size, composition and physical state of the core; 2) Determine the thickness and structure of the crust; 3) Determine the composition and structure of the mantle; 4) Determine the thermal state of the interior; 5) Measure the rate and distribution of internal seismic activity; and 6) Measure the rate of impacts on the surface. To accomplish these objectives, GEMS carries a tightly-focused payload consisting of 3 investigations: 1) SEIS, a 6-component, very-broad-band seismometer, with careful thermal compensation/control and a sensitivity comparable to the best terrestrial instruments across a frequency range of 1 mHz to 50 Hz; 2) HP3 (Heat Flow and Physical Properties Package), an instrumented self-penetrating mole system that trails a string of temperature sensors to measure the planetary heat flux; and 3) RISE (Rotation and Interior Structure Experiment), which uses the spacecraft X-band communication system to provide precision tracking for planetary dynamical studies. The two instruments are moved from the lander deck to the martian surface by an Instrument Deployment Arm, with an appropriate location identified using an Instrument Deployment Camera. In order to ensure low risk within the tight Discovery cost limits, GEMS reuses the successful Lockheed Martin Phoenix spacecraft design, with a cruise and EDL system that has demonstrated capability for safe landing on Mars with well-understood costs. To take full advantage of this approach, all science requirements (such as instrument mass and power, landing site, and downlinked data volume) strictly conform to existing, demonstrated capabilities of the spacecraft and mission system. It is widely believed that multiple landers making simultaneous measurements (a network) are required to address the objectives for understanding terrestrial planet interiors. Nonetheless, comprehensive measurements from a single geophysical station are extremely valuable, because observations constraining the structure and processes of the deep interior of Mars are virtually nonexistent. GEMS will utilize sophisticated analysis techniques specific to single-stationmeasurements to determine crustal thickness, mantle structure, core state and size, and heat flow, providing our first real look deep beneath the surface of Mars."

A reader asked in a comment to the previous post whether a single station severely compromised the return of a geophysical mission to Mars compared to a network of several missions.  This question was addressed in a presentation to the Mars Panel of the Decadal Survey (http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Mars2%20Banerdt%20rev.pdf).  The short answer is that a single station would be a major step forward, even though multiple stations would be ideal.  Since a three to four station network would likely be a small Flaghsip mission, a single station would begin the surface geophysical study of Mars.

MSR would be a completed Mars Sample Return; MAX-C was the proposed NASA rover to collect samples for MSR, and if it flies, it will be a joint rover mission with ESA.

Discovery Mission Candidates Announced

An artist's concept portrays the proposed Geophysical Monitoring Station mission for studying the deep interior of Mars. Image Credit: NASA/JPL-Caltech

NASA today announced the three selected candidates for the next Discovery mission selection, including a Mars geophysical station, a Titan lake probe, and a comet multiple lander mission.  Early versions or related concepts for these proposals were described in previous posts, and I have provided links to those posts.  It is likely that the concepts for these missions have matured and changed since the posts describing them.



NASA also announced funding for three mission concepts to mature their designs for possible selection in the future.


Editorial note: These all sound like excellent missions, and any would add significantly to our knowledge of the solar system.  I am encouraged that the list includes an outer planets proposal, giving  hope that the Discovery program can be used to fly missions to these distant worlds.


NASA's press release (http://www.nasa.gov/home/hqnews/2011/may/HQ_11-132_Future_Plantary.html) follows:


RELEASE : 11-132
  
NASA Selects Investigations For Future Key Planetary Mission
  
WASHINGTON -- NASA has selected three science investigations from which it will pick one potential 2016 mission to look at Mars' interior for the first time; study an extraterrestrial sea on one of Saturn's moons; or study in unprecedented detail the surface of a comet's nucleus. 


Each investigation team will receive $3 million to conduct its mission's concept phase or preliminary design studies and analyses. After another detailed review in 2012 of the concept studies, NASA will select one to continue development efforts leading up to launch. The selected mission will be cost-capped at $425 million, not including launch vehicle funding. 


NASA's Discovery Program requested proposals for spaceflight investigations in June 2010. A panel of NASA and other scientists and engineers reviewed 28 submissions. The selected investigations could reveal much about the formation of our solar system and its dynamic processes. Three technology developments for possible future planetary missions also were selected. 


"NASA continues to do extraordinary science that is re-writing textbooks," said NASA Administrator Charles Bolden. "Missions like these hold great promise to vastly increase our knowledge, extend our reach into the solar system and inspire future generations of explorers." 
The planetary missions selected to pursue preliminary design studies are: 

• Geophysical Monitoring Station (GEMS) would study the structure and composition of the interior of Mars and advance understanding of the formation and evolution of terrestrial planets. Bruce Banerdt of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., is principal investigator. JPL would manage the project.  [Editorial note: This previous post describes a two station Mars geophysical network, while the short description for this candidate proposal suggests it may be for a single station.]
• Titan Mare Explorer (TiME) would provide the first direct exploration of an ocean environment beyond Earth by landing in, and floating on, a large methane-ethane sea on Saturn's moon Titan. Ellen Stofan of Proxemy Research Inc. in Gaithersburg, Md., is principal investigator. Johns Hopkins University's Applied Physics Laboratory in Laurel, Md., would manage the project. 
• Comet Hopper would study cometary evolution by landing on a comet multiple times and observing its changes as it interacts with the sun. Jessica Sunshine of the University of Maryland in College Park is principal investigator. NASA's Goddard Space Flight Center in Greenbelt, Md., would manage the project. 

"This is high science return at a price that’s right," said Jim Green, director of NASA’s Planetary Science Division in Washington. "The selected studies clearly demonstrate a new era with missions that all touch their targets to perform unique and exciting science." 


The three selected technology development proposals will expand the ability to catalog near-Earth objects, or NEOs; enhance the capability to determine the composition of comet ices; and validate a new method to reveal the population of objects in the poorly understood, far-distant part of our solar system. During the next several years, selected teams will receive funding that is determined through contract negotiations to bring their respective technologies to a higher level of readiness. To be considered for flight, teams must demonstrate progress in a future mission proposal competition. 


The proposals selected for technology development are: 

• Primitive Material Explorer (PriME) would develop a mass spectrometer that would provide highly precise measurements of the chemical composition of a comet and explore the objects' role in delivering volatiles to Earth. Anita Cochran of the University of Texas in Austin is principal investigator. 
• Whipple: Reaching into the Outer Solar System would develop and validate a technique called blind occultation that could lead to the discovery of various celestial objects in the outer solar system and revolutionize our understanding of the area's structure. Charles Alcock of the Smithsonian Astrophysical Observatory in Cambridge, Mass., is principal investigator. 
• NEOCam would develop a telescope to study the origin and evolution of NEOs and study the present risk of Earth-impact. It would generate a catalog of objects and accurate infrared measurements to provide a better understanding of small bodies that cross our planet's orbit. Amy Mainzer of JPL is principal investigator. 

Created in 1992, the Discovery Program sponsors frequent, cost-capped solar system exploration missions with highly focused scientific goals. The program's 11 missions include MESSENGER, Dawn, Stardust, Deep Impact and Genesis. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the program for the agency's Science Mission Directorate.