ESA Plans Test of Asteroid Defense System

vinlud writes "It has been announced by Dutch television ESA has chosen the Don Quijote programme to investigate the possibilities of altering the collision course of asteroids heading for Earth. The program, selected among five other studies, contains two spacecraft: Hidalgo and Sancho. Hidalgo will impact an asteroid of approximately 500 m diameter at a relative speed of at least 10 km/s while Sancho will retreat to a safe distance to observe the impact. An animation of the mission sequence (6.49 Mb) can be downloaded from here."

Comments

so....

[bman08]

is this just a hip way to repackage missile defense testing so that nobody gets mad?

Re:Bull's eye!

[Rob Carr]

It's definitively more exciting but I wonder if it's not too hard to make such a millions miles away 'bull's eye'. 500 m in diameter is pretty small at this distance...

With the ability to correct the flight enroute, it shouldn't be too difficult at all. When Cassini went into orbit around Saturn, the navigation was so precise that they did not need to do a corrective burn.

Still, if for some gosh-awful reason you can't hit a 500 m target, this is the perfect time to find out!

Here's a bunch of folks that will probably have fun looking to see what effect the collision might have: The folks on the Minor Planet Mailing List are really into tracking the orbits of these rocks. I wouldn't be surprised if their data is the stuff that narrows the error bars on this experiment!

Number Crunching

[Rob Carr]

Assuming that the Hildalgo probe masses in at 25 kg (the same as Sancho - it might be less) and is moving at 10km/sec and assuming the asteroid has a density of 3g/cc (giving a mass of 4x10^10 kg, and if the probe is absorbed into the asteroid and no material is lost from the asteroid, then the change of velocity for the asteroid will be about 6x10^-9 km/sec.

For comparison, the asteroid probably has a velocity somewhere on the order of 5-10km/sec.

If the asteroid and probe hit head on with both having a velocity (relative to the sun) of 10km/sec, then you can double the change to 1.2x10^-8 km/sec

It's probably a good idea to check my work. Here's how I did the calculation:

Let m1 be the probe and m2 be the asteroid.

v(center of mass)=(m1*v1+m2*v2)/(m1+m2). v2=0 for this reference frame and m1+m2 essentially equals m2. Since we're in the reference frame of the asteroid being stationary, the combination of probe and asteroid will still have the same velocity for the center of mass.

I hope I didn't botch this estimate....