Eyes in the Skies

Q: Instead of sending space probes to distant planets, is it possible to land a powerful camera or another instrument on a comet or asteroid — and have it send back information as it travels through space?

A: “It is certainly possible to land a camera with other instruments on a comet or asteroid to take images of that object and its surroundings,” said Lindley N. Johnson, planetary defense officer at NASA headquarters in Washington.

In fact, this has already been done.

“However, space is a very big place,” Johnson continued. “And even within our solar system, the comet or asteroid would almost never come close enough to a planet or another comet or asteroid to collect any images of any scientific value.”

While very small asteroids do come close to Earth every week, he said, the closest that any comet or asteroid larger than 1 mile in size has come to Earth in the past century was still more than 1 million miles away, roughly four times the distance from the Earth to the moon.

The European Space Agency’s Rosetta mission landed a probe, Philae, on Comet 67P/Churyumov-Gerasimenko in 2015. The Near Earth Asteroid Rendezvous — Shoemaker mission landed on the asteroid Eros in 2001, he added.

Other missions have briefly touched down on asteroids to collect samples from them, Johnson said.