1. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Stardust NExT Tim Larson, Project Manager EPOXI and Stardust NExT NASA – Jet Propulsion Laboratory 1 The Next Chapter For a Proven Comet Chaser

2. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Comet Tempel 1 First visited by Deep Impact –Impactor delivered to the comet on July 4, 2005 –Resulting collision excavated sub- surface material –Flyby spacecraft captured high resolution images and IR spectra of the comet nucleus in addition to the ejecta plume (500 km flyby distance) –Ejecta plume was larger than predicted by many models Indicates weak forces holding nucleus material together –The nucleus showed an extremely varied terrain Smooth flows Water ice patches Layered terrain Craters that could be due to impacts or eruptions of material Rough, pitted terrain 2

3. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Tempel 1 Morphology 3

4. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology History of Stardust Spacecraft Stardust –Launched in February 1999 –Interstellar dust collection in 2000 –Encountered asteroid Annefrank in 2002 –Visited comet Wild 2 in 2004 –Stardust flew through the coma of Wild-2 (240 km distance from the nucleus) Collected coma dust samples in the sample capsule Measured dust flux with the DFM instrument Collected images of the comet nucleus with the Navcam –Samples were successfully returned to earth in January 2006 4

5. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology The Sample Return - 2006 5

6. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Re-purposing a Spacecraft Typical challenges: –Is there enough fuel? – needed to adjust trajectory, fine tune aim points for flyby, spacecraft pointing (either directly with thrusters or to unload the reaction wheels) –Power – will solar arrays generate enough power at new solar distances? –How long will it take to get to the new target? –Life limited equipment – gyros, reaction wheels, batteries, etc. –Condition of spacecraft – have there been any equipment failures or malfunctions? –Can the telecommunication system (radio and antennas) support the necessary data rates? –What can the instrument suite support? –Will the science collected be worth the cost of maintaining a mission team? 6

7. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Stardust NExT After dropping off sample capsule, s/c diverted its course to miss the earth and continued in its heliocentric orbit Spacecraft was healthy, but low on fuel Innovative mission design used Trajectory Correction Maneuvers and Earth Gravity Assist to modify orbit to intersect with Tempel 1 First opportunity to visit a comet on two consecutive perihelion passes 7

8. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Stardust → NExT Stardust’s new mission – New Exploration of Tempel-1 (NExT) –Unique opportunity to observe a comet up close on two successive perihelion passes –Compare changes on the surface between two successive passes near the sun (2005 and 2011) –Extend the mapping of the nucleus to previously unseen areas –Follow up on interesting features observed by Deep Impact –If possible, image the crater left by the Deep Impact Impactor spacecraft Principal Investigator: Dr. Joe Veverka from Cornell University Partners: Lockheed Martin Space Systems, Denver, operate the spacecraft 8

9. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Why Study Comets? Comets contain the materials that were present at the beginning of the solar system, 4.5 billion years ago Understanding the materials present in comets and their formation dynamics will help us understand the early history and processes at work in our solar system Comet impacts may have contributed to the water and organics present on our own planet NASA comet exploration –Deep Space 1 – flew by comet 19P/Borrelly in 2001 –Stardust – flew by comet Wild-2 in 2004 –Deep Impact – impact and flyby of Tempel-1 in July 2005 –EPOXI – Hartley-2 flyby November 2010 –Stardust NExT – Tempel-1 flyby February 2011 –Rosetta – NASA-built instruments on board ESA spacecraft to visit comet 67P/Churyumov-Gerasimenko in 2014 9

10. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Why Study Comets? Comets contain the materials that were present at the beginning of the solar system, 4.5 billion years ago Understanding the materials present in comets and their formation dynamics will help us understand the early history and processes at work in our solar system Comet impacts may have contributed to the water and organics present on our own planet NASA comet exploration –Deep Space 1 – flew by comet 19P/Borrelly in 2001 –Stardust – flew by comet Wild-2 in 2004 –Deep Impact – impact and flyby of Tempel-1 in July 2005 –EPOXI – Hartley-2 flyby November 2010 –Stardust NExT – Tempel-1 flyby February 2011 –Rosetta – NASA-built instruments on board ESA spacecraft to visit comet 67P/Churyumov-Gerasimenko in 2014 10

11. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Challenges Large orbital periods and trajectory uncertainties as well as unpredictable behavior make comet exploration challenging Flying nearby a comet nucleus requires ground based observations combined optical navigation from the spacecraft Flyby challenges –Flyby velocities are in the range of 10 m/sec (approximately 22,000 mph) –Even with large telescopes there is limited time to take high resolution images – comet is approaching and departing too fast Well timed imaging sequence to capture closest approach –Getting close enough to the nucleus requires flying through the coma – dust impact risks Stardust has robust shields on the front end of spacecraft –Imaging specific sides of the comet is extremely challenging Rotational period of comets is difficult to determine Rotational rate changes every perihelion Makes predictive ability to predict what side of comet will be seen uncertain 11

12. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology 12 Comet Wild-2 ←From Earth Nucleus up close→ (long and short exposures combined to show jet activity) ← Tempel-1 jet activity Hartley 2 from DI S/C→

13. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology If Everything Goes as Planned 13

14. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Encounter Timeline February 14, 2011 E-24 hrs – upload final sequence and comet ephemeris files E-3 hrs – CIDA (Comet and Interstellar Dust Analyzer) on E-1 hr – s/c turns to flyby attitude (shields in velocity direction) E-30 min – Autonav goes active – will control camera mirror position and s/c roll during flyby to keep nucleus centered in field of view E-20 min – DFM (Dust Flux Monitor) on E-0 – Closest Approach – approximately 8:30 PM Pacific time –S/C 200 km from comet nucleus E+20 min – DFM off E+1 hr – S/C turns back to Earth point (High Gain Antenna to earth) E+3 hr – first images of closest approach transmitted to ground E+3 hr – CIDA off 14

15. National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology 15