[meteorite-list] New Research Explores Asteroid Deflection Using Spaceraft to Crash Into Body at High Speeds

[Ron Baalke]

http://phys.org/news/2016-02-explores-asteroid-deflection-spacecraft-body.html

New research explores asteroid deflection using spacecraft to crash into body at high speeds
phys.org
February 17, 2016
 
Asteroids headed for a collision with the Earth, if found early enough, 
can be acted upon to prevent the potentially devastating consequences 
of an impact. One technique to divert an asteroid, called kinetic impact, 
uses a spacecraft to crash into the body at high speeds.

This approach delivers the momentum of the spacecraft, while also providing 
an additional boost of momentum through the production of impact crater 
ejecta exceeding the asteroid's escape velocity. Researchers at Lawrence 
Livermore National Laboratory (LLNL) have been studying the effectiveness 
of the kinetic-impactor strategy by carrying out 3D simulations of the 
process.

In a new paper published in Icarus (link is external), LLNL planetary 
defense researchers find that asteroid deflection by kinetic impact is 
sensitive to a range of asteroid characteristics, including strength, 
porosity, rotation and shape. These and other asteroid properties may 
not be well constrained before an actual deflection mission is staged, 
leading to variability in the deflection outcome. By simulating a range 
of initial conditions for the target asteroids, researchers were able 
to quantify, for example, how greater target strength decreases the delivered 
momentum impulse and how, for an asteroid of constant size, added porosity 
can result in more effective deflections, despite the dampening of the 
shock waves produced during an impact.

[graphic]
In this model, asteroid Golevka (approximately 500 meters across) is impacted 
by a 10,000 kilogram mass traveling at 10 kilometers per second along 
a principal axis of the asteroid. Colors denote the accumulation of damage. 
The final change in asteroid velocity for this example is approximately 
1 millimeter per second.

The kinetic-impact approach is one of the most mature technologies for 
deflecting a hazardous asteroid. For cases where the warning time is known 
well in advance and the asteroid is not too large, it is the preferred 
deflection mechanism, as described in a 2010 National Research Council 
report (link is external).

"Asteroids are naturally diverse, and researchers have little direct information 
about their mechanical properties," said Megan Bruck Syal, lead author 
on the paper. "This study emphasizes the important role of asteroid characterization 
research, which is needed to constrain the different types of conditions 
that could be encountered at potential deflection targets."

These results provide new information on the range of possible responses 
to a kinetic deflection attempt, which can directly inform the design 
of future kinetic-impact missions. The simulation results also are potentially 
useful for the interpretation of results from rare, full-scale impact 
tests, such as the Asteroid Impact and Deflection Assessment mission's 
planned impact of the Didymos secondary in 2022.

Explore further: New map shows frequency of small asteroid impacts, provides 
clues on larger asteroid population

More information: Megan Bruck Syal et al. Deflection by kinetic impact: 
Sensitivity to asteroid properties, Icarus (2016). DOI: 10.1016/j.icarus.2016.01.010 

Journal reference: Icarus    

Provided by: Lawrence Livermore National Laboratory