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Stardust NExT

Stardust NExT. The Next Chapter For a Proven Comet Chaser. Tim Larson, Project Manager EPOXI and Stardust NExT NASA – Jet Propulsion Laboratory. Comet Tempel 1. First visited by Deep Impact Impactor delivered to the comet on July 4, 2005 Resulting collision excavated sub-surface material

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Stardust NExT

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  1. Stardust NExT The Next Chapter For a Proven Comet Chaser Tim Larson, Project Manager EPOXI and Stardust NExT NASA – Jet Propulsion Laboratory

  2. 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

  3. Tempel 1 Morphology

  4. 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

  5. The Sample Return - 2006

  6. 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?

  7. 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

  8. 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

  9. 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. 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

  11. 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

  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. If Everything Goes as Planned

  14. Encounter TimelineFebruary 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

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