China Plans Deep Impact Mission

Comatose51 writes "China is planning its own Deep Impact mission. The goal of the mission, unlike the exploratory NASA project, is to push potential life-ending comets or asteroids away from a collision course with the earth." From the article: " The third nation to launch a man into space has lofty space ambitions that include putting two astronauts into orbit this September and eventually sending up a space station and even a manned mission to the moon."

Comments

The math doesn't look good...

[G4from128k]

An estimate of the orbital delta-v for Tempel /Deep Impact suggests a velocity change of only 1 cm/hour (I can't vouch for the math). Assuming we would need to nudge a threatening body by 1/2 the diameter of the Earth (from direct hit to grazing pass-by), we would need to know to hit a Tempel 1-sized body in advance by over 73,000 years. This type of mission would work 10 years in advance for much smaller bodies (say less than 350 m in diameter). Even these estimates assume a perfect strike by the deflecting deep impactor -- a margin of error or the need to push the object several Earth-diameters further reduces the potential for this method.

Kinetic energy is not the way to go. Deep Impact delivered only about 4.5 kt of TNT. In contrast, a good sized thermonuclear weapon could deliver thousands of times that energy (even taking into account the relatively poor conversion of 100 megatons yield into delta-V).