Transcript Rosetta - BTE999

Rosetta
Terry Evans
2014 October 8th
Rosetta
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Name?
Objectives?
What’s on board?
Target?
How to get there?
What’s happened so far?
What next?
Name?
• Named after the Rosetta Stone
– Now in the British Museum
Name?
• Named after the Rosetta Stone
– Now in the British Museum
• Philae named after an island in the Nile
– An obelisk on the island helped the process of
translation of hieroglyphic script
– Now at Kingston Lacy, Dorset
Objectives?
• Rendezvous with a comet
• Orbit the comet to follow it
• Land a probe on the comet
• Based on the cancelled NASA CRAF mission
What’s on Board?
• Main Rosetta Orbiter
Rosetta Main Craft
What’s on Board?
• Main Rosetta Orbiter
• Philae Lander
Rosetta Orbiter
• Mass 2,900 kg (plus fuel)
• 64 sq m of solar cells for electrical power
• Not enough power to keep the craft powered
when far from the sun
• 24 “hydrazine” 10N thrusters with 1,670 kg
fuel
• 22 kbps link to Earth
Philae Lander
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Mass 100 kg
Solar cells for 32 W electrical power
No thrusters
Uses Rosetta for relay link to Earth
What’s on Board?
• Instruments to measure
– The nucleus
– The coma (gas and dust)
– Interaction with the Solar Wind
• Philae has instruments to measure
– Composition of the surface
– Gas and dust
– Subsurface using a drill
Orbiter Instruments
• Imaging camera
• Spectrometry in UV, Optical, IR & Microwaves
– ALICE,OSIRIS,VIRTIS & MIRO
• Mass Spectrometry & impact of gas & dust
– ROSINA,COSIMA,MIDAS ,GIADA
• Solar Wind measurement – RPC
• Tomography of the nucleus using radio comms
between Rosetta and Philae - CONSERT
Philae Instruments
• Imager - ROLIS
• Surface measurements in X-ray, Light & Sound
– APXPS,CIVA,SESAME
• Isotope, Mass, Magnetic field & direct sensing
– Ptolemy,COSAC,ROMAP,MAPUS
• SD2 - Drill samples for COSAC,CIVA & Ptolemy
• Philae half of CONSERT
UK involvement
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Main platform built by Astrium, Stevenage
Batteries – AEA, Scotland (now Ricardo-AEA)
RAL – Ptolemy instrument
VEGA – On board software (now Telespazio
VEGA)
• SciSys – Mission Control System & Flight
Dynamics
• Various universities – Data Analysis
Target?
• Looking for a “Jupiter family” comet
– Captured by Jupiter
– Orbit < 20 years
– Probably originally Kuiper belt objects
• Want a relatively young comet
• There are lots of Jupiter family comets!
Target?
• Originally going to be 46P/Wirtanen BUT
– Ariane 5 launcher failed in December 2002
– Delayed planned launch in January 2003
• New target is 67P/Churyumov–Gerasimenko
67P/Churyumov–Gerasimenko
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Discovered in 1969
Klim Churyumov & Svetlana Gerasimenko
Both Ukrainians working in Alma-Ata (Almaty)
Actually photographing 32P/Comas Solà
Orbit 6.45 years, Rotation 12.4 hrs
Next at perihelion 13th August 2015
4.5 km major axis
67P from the ESO VLT
How to get there?
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Craft too heavy for direct route
Complicated path with 3 Earth & 1 Mars flybys
Rendezvous with asteroids Šteins and Lutetia
Hibernation phase to conserve batteries
Wake up phase and rendezvous with 67P
Orbit 67P
Philae Landing
Follow 67P around perihelion
What’s happened so far?
• Launch 2004 March 2nd from Kourou, French
Guiana (after 2 aborted attempts)
• Earth flyby 2005 March 5th
• Mars flyby 2007 February 25th (eclipse)
• Earth flyby 2007 November 13th (2007 VN84)
• Šteins flyby 2008 September 5th
2867 Šteins
2867 Šteins
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Discovered 1969
7 km major axis
Diamond shaped
One large crater (Diamond)
Very soft “eroded” terrain
What’s happened so far?
• Launch 2004 March 2nd from Kourou, French
Guiana (after 2 aborted attempts)
• Earth flyby 2005 March 5th
• Mars flyby 2007 February 25th (eclipse)
• Earth flyby 2007 November 13th (2007 VN84)
• Šteins flyby 2008 September 5th
• Earth flyby 2009 November 12th
• Lutetia flyby 2010 July 10th
21 Lutetia
21 Lutetia
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Discovered 1852
120 km major axis
Largest crater 45 km
Metal rich
Hibernation & Rendezvous
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Hibernation 2011 July 8th
Wake-up 2014 January 20th
Main rendezvous burn 2014 May 7th (8 in all)
Arrive at 67P 2014 August 6th
First Images of 67P from Rosetta
2014 July 20th “Rubber Duck” images
Activity in August
2014 August 8th
Close-up of “Neck”
Orbit & Mapping
• Mapping of comet started 2014 August
• Mapping orbit entered 2014 September 10th
– 29 km orbit. Expected to drop to 19 km
• Lander site chosen 2014 September 15th
Philae Potential Landing Sites
Chosen Site “J”
Site “J”
• Least challenging terrain
• Less than 30 degree slopes
• Signs of activity nearby
Science so far
• Very dark in UV
• Water vapour production detected >5 l/s and
increasing
• No water ice detected on the surface
• Detected carbon monoxide, carbon dioxide,
ammonia, methane, methanol
• Dust between 10 and a few hundred microns
What Next?
• Landing due on 2014 November 12th
Philae Landing
• Philae will release from Rosetta at about 22
km altitude and free-fall for ~7 hours
• Falls at about 1 m/s (3.6 km/hr)
• Escape velocity is ~0.5 m/s (1/10,000 Earth’s)
• Legs will cushion impact
• Harpoons fired to anchor to the comet
• All done without ground control!
What Next?
• Landing due on 2014 November 12th
• Main “escort” phase starts December
• Watch 67P “turn-on” as it nears the sun
– May need to vary Rosetta’s orbit
• Follow through perihelion and “turn-off”
Possible Science
• Whether 67P is a contact binary or eroded
around the neck
• Organic compounds & chirality of amino acids
• Size and composition of dust grains
• Production of cyanogen
• ... And lots more