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Deflecting APOPHIS with a Flotilla of Solar Sails Jean-Yves Prado Olivier Boisard, Alain Perret,Guy...
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Transcript of Deflecting APOPHIS with a Flotilla of Solar Sails Jean-Yves Prado Olivier Boisard, Alain Perret,Guy...
Deflecting APOPHIS with a Flotillaof Solar Sails
Jean-Yves Prado Olivier Boisard, Alain Perret,Guy Pignolet U3P France
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ The case of Apophis
■ Keyholes and resonant orbits
■ The Yarkovsky Effect
■ Mitigation mission
■ Comparison with other deflection techniques
Outlines
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
APOPHIS
Discovery
Discovered by:
Roy A. Tucker,David J. Tholen, Fabrizio Bernardi
Discovery date: June 19, 2004
Orbital characteristics
Aphelion distance: 1.099 AU
Perihelion distance: 0.746 AU
Orbital period: 323.6 d (0.89 year)
Inclination: 3.331°
Physical characteristics
Dimensions: ~250 m (estimated)
Mass:
Rotation period ~30h
2×1010 kg (estimated)
Mass of APOPHIS ~ 200 x @V=40,000 km/h
426 Days =>2036
417 Days =>2037
APOPHIS Fly by of the Earth on April 13, 2029
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
KEYHOLES
Orbit Uncertainty
+
-Earth
asteroid
+ Earth Gravity Assist
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
426.125 d
417.43 d
Possible Resonant Orbits
2037
2036
Resonant orbits up to 2130
0
20
40
60
80
100
120
140
417 419 421 423 425 427
APOPHIS Period (Days)
Ye
ar
of
retu
rn (
-20
00
)
1 s
Resonance Condition: Tap=m/n TEarth
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
KH distance distribution
XX = Year – 2K
‘safe area’
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
The Yarkovsky Effect
Ivan Osipovich Yarkovsky1844-1902
From PhD thesis Miroslav Broz, Charles University, Prague 2006
1987: Small variations in motion of LAGEOS explained using Yarkovsky theory
2003: First time measured on an asteroidGOLEVKA (Chesley)
based on 1991-1999 data
May 2003
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
The Diurnal Yarkovsky Effect
YE depends on: Distance to the Sun Asteroid size Asteroid shapeRotation axis obliquityRotation rateThermal properties:
surface conductivity
thermal inertia
• Very sensitive for the 1 m / 10 km class of Asteroids• Seasonal effect can be neglected for >100m asteroids
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ Tiny effect (10-10 / 10-13m/s2) but permanent
■ Main effect on semimajor axis
■ Order of magnitude for da/dt variation of tens to hundreds meters per year
■ Position error varies with t2
■ Example: with da/dt =10m/year position shifts 100m in 1 year, 400 m in 2 years…
100m 1km 4 km
■ Can be positive (outward spiral) or negative (inward spiral) depending on obliquity
■ Determination of its direction and magnitude for propagating orbit parameters
with an accuracy coherent with keyhole sizes
■ General question, not specific to APOPHIS
Impact of the Yarkovsky Effect on the asteroid orbit
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ A Transfer Module using SEP carries 4 x 200 kg solar sails to be deployed near APOPHIS
■ Formation Flying mode of the sails controlled by the TM
■ The sails hover a few km over the asteroid
■ They can shadow only the surface which is the most effective w.r.t. YE
■ No direct link from the Earth to individual sails
■ Chemical propulsion needed for balancing the photonic pressure (DV ~1.1 m/s/day)
■ Photonic pressure could be decreased by using a mesh instead of a film screen
■ 2 sets of TM+SS required (so 2 launches) can be required for efficiency and reliability
Mission Design
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ High DV needed => Use of solar electric propulsion ■ Soyouz Fregat launch from Kourou assumed■ Typical mission profiles
Cruise
2011 option2016 option
2019 option
Departure date Dec. 14, 2011 Mar. 30, 2016 Dec. 5, 2019
Departure conditions v-inf = 3km/s, dec = -20.4deg v-inf=3.76 km/s, dec =-40 deg v-inf = 3km/s, dec = -18.4deg
Launch mass 1200kg 1200 kg 1200kg
Date of the Earth swing-by Apr. 18, 2013No Earth Swing-By
Apr. 11, 2021
Characteristics of the swing-by hp = 78000km, v-inf = 4.38km/s hp = 60000km, v-inf = 4.50km/s
Date of the rendezvous Mar. 5, 2014 Dec.22, 2018 Jan. 18, 2022
Total cruise duration 813 days (27 months) 997 days (33 months) 775 days (26 months)
Total Delta-V 1520m/s 1620 m/s 1350m/s
Xenon mass 95kg 100 kg 85kg
Final S/C dry mass 1105kg1100 kg
1115kg
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
2016 Departure
No Earth Swing By
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
2019 Departure
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22Image Credit Olivier Boisard
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ 2 categories: Impulsive/Slow Push Techniques
■ Impulsive techniques can be seen as a preliminar to send weapons in space
■ Slow Push Techniques (from NASA report to US Congress): Focused Solar Boil off material using large mirror Low TRL, complex Pulsed Laser Boil off material with a laser Low TRL Mass Driver Needs to land, Asteroid characteristics dependant Low TRL Gravity Tractor Efficiency in D-5, High TRL Asteroid Tug Needs to land, Asteroid characteristics dependant Low TRL Enhanced YE Heavy, Asteroid characteristics dependant Low TRL
YES Efficiency in ~D-1, High TRL but applicable only if YE is present
Comparison with Other Deflection Techniques
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
■ Cancelling YE can be an efficient and reliable method for deflecting a NEO < km
■ Effort in such technology would benefit several types of missions
■ Canceling YE for a given period of time, even if not needed for APOPHIS, would validate the feasibility of the method
■ The required technology is very similar to the one required for solar sailing
■ International coordination required
Conclusions
ISSS 2010 Deflecting Apophis with a flotilla of solar sails New York July 20-22
APOPHIS in the Egyptian mythology