This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.

11 May 2011

2011 IAA Planetary Defense Conference: Day 3 Session 6

Notes from Day 3 of 2011 IAA Planetary Defense Conference. Follow twitter feed for more information:

Day 3 (Wednesday 11 May 2011) Session 6
Mission Planning and Technologies

- Housen, K.
"Measuring the Momentum Transfer for Asteroid Deflection"
crater profile does not depend too much on void spaces
impact disruption of spinning bodies
rapid rotators will be more susceptible to disruption in a deflection mission
Beta for sand at 2km/s is 2, 10-20km/s for beta=3
beta may depend strongly on porosity

- Golubov
Influence of intermediate scale structure on Yarkovsky and YORP effects
YORP first pointed out by Rubincam
Asteroid Itokawa doe not demonstrate YORP model

- Andrew Klesh
Improved Navigation Techniques for Asteroid Landers and Impactors
based on JAXA work, Hayabusa 2 work

landed accuracy: NEAR (several hundred meters), Hayabusa, Marco Polo (3.5 n), H2 (several tens of meters)

Tracking features may not be an option
navigation by radio ranging

- Bombardelli, C.
"Ion Beam Shephred: A New Concept for Asteroid Deflection"

Ion Beam Shepherd (IBS)

primary ion engine pointed at asteroid surface, secondary propulsion to avoid IBS from drifting away from asteroid
currently under study by ESA and TU Madrid for space debris removal applications
beam divergence: need to make sure beam does not expand too much
for example. taking SOA thrusters, get 5-15 degrees and March of 20-30, handle 150 m diameter asteroid from a distance of 200m or less from center (50 m from surface)
force transmitted: penetrate asteroid surface a few nanometers, backsputtering is low
can beam pressure damage asteroid: local beam mechanical pressure: for example for 100m diameter asteroid, a 10N beam gives a peak pressure of less than 6mPa
for one year of thrusting have a Isp - 9000s
with Isp = 3k seconds
for asteroid below 500m gravity force is low
slow push asteroid deflection performance,
case: 2007 VK184 (D=130m)
1 N thrust for 2 years = 5 MT IBS (3000 sec Isp)
Gravity tractor needs more mass for same effect as IBS (50 MT needed for 150 m asteroid)

- Hayabusa2 Mission (Yoshikawa) - presented by alternative
has become project (Phase B)
budgetary request for H2 project was approved, on May 1, 2011 status of project becomes Phase B and under PDR (Preliminary Design Review)
C-type (1999 JU3) target now
0.922 km , around 1km in size (not irregular)
Spectrum is different
Launch of July 2014, arrival in June 2018, 3 samplings (sample, crater, and 2 samplings), reath return in 2019/2020,
500 m altitude release, canister will explode with projectile release, spacecraft will fly over crater and take sample)
small lander (MASCOT - under discussion): DLR/CNES MASCOT (10 kg lander) Mobile Asteroid Surface Scout
NASA: similar as H1
international collaboration may be possible
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