1 / 24

Mission: Comet

Mission: Comet. Renee French, Amy Jia, Lisa Mithun May 10, 2011. What is a comet?. Icy body with nucleus, coma, and tail Nucleus: ice, dust, small rocky particles, frozen gases Size: range from a few hundred meters to tens of km across, irregular

mufutau-kramer
Download Presentation

Mission: Comet

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mission: Comet Renee French, Amy Jia, Lisa Mithun May 10, 2011

  2. What is a comet? • Icy body with nucleus, coma, and tail • Nucleus: ice, dust, small rocky particles, frozen gases • Size: range from a few hundred meters to tens of km across, irregular • Origins: Kuiper Belt, Oort Cloud – formation in the outer solar system • Orbital periods: range from a few years to thousands of years or follow hyperbolic trajectories 1http://stardust.jpl.nasa.gov/science/why.html 2 Image: http://t3.gstatic.com/images?q=tbn:ANd9GcT2P3_P9nskrj4QjUJLDaK93Hd5FMzDL27ly9OYozgBk6M_nsTc8A

  3.  Relationship to life on Earth Why do we think life could have originated in this way? • Collisions • Common in early solar system • Craters on the moon • Shoemaker-Levy & Jupiter • Comets could contain: • Untouched samples of early solar system, proto-planet/nebular material • Water • Organic compounds • Amino acids Miller-Urey Experiment 1http://stardust.jpl.nasa.gov/science/why.html 2 Image: http://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Schwassman-Wachmann3-B-HST.gif/220px-Schwassman-Wachmann3-B-HST.gif

  4. Evidence that it could seed life • Not necessarily panspermia • Also, while unlikely, not ruling out life 1 m down • Though conditions are extreme, there would be shielding of solar radiation • Discovery of glycine in comets is the basis of a theory and not definitive • A long way from glycine to life • Strengthens Rare Earth Hypothesis 1 http://stardust.jpl.nasa.gov/science/life.html 2 Image 1: http://t0.gstatic.com/images?q=tbn:ANd9GcTv2viQtU-IJyf3IUaQJyqIf1lmpg_1sshNDF9KoYClB4L0x5T1rg 3 Image 2: http://www.daviddarling.info/images/glycine.jpg

  5. Stardust at comet Wild 2 (2006) - Samples collected with aerogel     - highly porous     - density of air: slows particles and prevents melting or vaporization. - Instruments     - navigational cameras     - dust analyzer         - mass spectrometer         - real time info     - dust flux/size distribution       monitor     - dynamic science experiment         - determine mass of comet                density ->0.6g/cm^3 Burnett, Nasa Returns Rocks from a Comet, 2006 http://www.nasa.gov/mission_pages/stardust/spacecraft/index.html

  6. Track variability - Track morphology reflects physical properties of particle, size dependent • cohesive material made "carrot-type" tracks • poorly consolidated material made "turnip-type" tracks • fine grain material or volatiles made bulbous cavities Brownlee et al., Comet 81P/Wild 2 Under a Microscope, 2006 Horz et al., Impact Features on Stardust: Implications for Comet 81P/Wild 2 Dust, 2006

  7. Stardust findings -Composition     - anhydrous olivine (Fo4-Fo100), pyroxene, troilite(FeS) most abundant     - labile organics rich in O, N •  naphthalene, phenanthrene, pyrene -> resembles Murchison     - amines methylamine and ethylamine - Ejected particles indicate no previous heating, compaction or aqueous alteration • Cohesive and self supporting surface - not rubble pile Brownlee et al., Comet 81P/Wild 2 Under a Microscope, 2006 Sandford et al., Organics Captured from Comet 81P/Wild 2 by the Stardust Spacecraft, 2006

  8. Stardust rendezvous with Tempel 1 - Flew past Tempel 1  on Feb 15, 2011 - Analyzed surface  changes from impact  and Sun approach http://www.nasa.gov/mission_pages/stardust/main/index.html

  9. Deep Impact and Tempel 1 (2005) - 370 kg object created a crater 150 m diameter, 30 m deep • Composition • amorphous/crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas/ice, sulfides • consistent with solar and chondritic abundances • indicates mixing over large distances in protosolar disk - A total of 5e6 kg of water and 10-25e6 kg of dust were lost from impact http://www.nasa.gov/mission_pages/deepimpact/main/

  10. Can organic materials survive impact? • Water and organic molecules may survive impact • If low enough angle • Sufficient drag from Earth’s atmosphere to slow comet • Early bombardment was heavy enough to deliver a significant amount of intact organic material and water Blank et al, 2001

  11. Blank et al: Collision Study • Jennifer G. Blank • Department of Earth and Planetary Science • University of California, Berkeley • 3 year project to design a steel capsule that would not rupture when hit with a bullet traveling 1.6 km/sec. • The target was a 2 cm wide stainless steel 0.5 cm thick filled with 5 amino acids and a drop of water • able to withstand about 200,000 times atmospheric pressure without bursting

  12. Schematic diagram of Blank et al.'s apparatus. The red arrow indicates the projectile fired from the breach toward the stationary target (inset). The 3 smaller red triangles indicate transducer pins that measure the velocity of the projectile as it passes. Upon impact, the sample container flies backwards into the recovery area, where it is trapped as gently as possible in layers of felt. NASA, 2001

  13. Blank et al: Results • Most amino acids survived the simulated comet collision • Created every possible combination of dipeptide, many tripeptides and some tetrapeptides • Saw variations in the ratios of peptides produced depending on the conditions of temperature, pressure and duration of the impact.

  14. Nir Goldman et al: Study of Comet Shockwaves • Studied molecular dynamics simulations of shock waves after a comet strike to see if organic materials could survive the conditions during and after impact • The team found that the shock waves from a comet's impact can promote short-lived C-N bonded oligomers • When the pressure dropped after impact, these oligomers break up to form stable complexes containing the amino acid glycine.  • Evidence for complex organic chemistry under conditions of extreme pressure and temperature Royal Society of Chemistry, 2010

  15. Past Missions • Stardust mission, 1994: collected interstellar dust and particles on the surface of the comet using aerogel collectors • Evidence of life more likely to be found inside comet Photo (top): www.optics.rochester.edu Photo (below): astrophys-assist.com

  16. Past Missions • Deep Impact • Launched in 2004 • NASA • In 2005, released an impactor that collided with 9P/Tempel’s nucleus • Excavated debris from interior • 2006, sample capsule returned to Earth • Photographs of impact showed composition of comet to be dustier and less icy • unable to image the crater because of the unexpectedly dense and opaque debris cloud • Reused spacecraft NASA, 2006

  17. CurrentMissions • Rosetta • European Space Agency • 2004-2014 • Comet 67P/Churyumov-Gerasimenko • will land a probe on the comet and drill for core samples • First probe to orbit a comet • First deep space mission to rely on solar panels for power, rather than nuclear-generated power • 2 Fly-by missions of asteroids completed Spacetoday.org

  18. Current Missions • Champollion / Deep Space 4 (Cancelled in 1999) • April 2003 • NASA • planned to go into orbit around nucleus of Tempel 1 in April 2006. • 100 kg lander would land on surface and drill 1 meter down to collect samples of the nucleus • On-board analysis with results transmitted to Earth (NASA, 2010)

  19. Next Mission • Our plan: To land a probe on the comet and drill one meter down to sample the interior of the comet • Technical Issues: • gentle landing to avoid harming probe • Reduced speed to photograph comet • contamination of samples • Choosing suitable comet

  20. Future mission: which comet? - Tempel 1     - water (clays, carbonates)     - organic molecules     - hypothesized to have formed in Uranus/Neptune-Oort Cloud       region (interior chemistry)     - Short period (5.52 years) - Good agreement between  Tempel 1 and Hale-Bopp  compositions -> non-uniqueness Image from Ahearn et al., Whence Comets?, 2006

  21. Costs • Rosetta (2004): • Projected: $900 million US • Actual: $1.2 billion US (over $80 million in delays) • Deep Impact (2004): • $328 million total • Stardust (1999): • $199.6 million total • $150 million: cost of development and construction of the spacecraft. • $30 million to reuse spacecraft

  22. Projected Costs • $1.5 billion total • Pros: • Lower cost than most deep space missions • reuse spacecraft • “gravity assist” trajectory decreases fuel costs • Technology for sampling and analysis already exists • Cons: • "gravity assist" trajectory extends timeline • Delays significantly increase cost

  23. The next 15 years • Assess what the major problems were last time and what we should do differently • Generate ideas on multiple targets to reduce cost or plans to recycle probe • Build new probe • After determining target comet and trajectory, determine mission length • A 6-10 year mission would allow for 5-9 years of building and planning • Prepare technical equipment • Engineer a tool small enough to add to the probe • Ability to drill, scoop, keep safe from re-entry and keep clean

  24. Based on what we found, did a comet seed life on Earth?

More Related