Could We Hit Mars With This Comet?

[Moontanman]

A a dress rehearsal for deflecting a comet from Earth do we currently have the ability to affect the course of this comet so it actually hits Mars? It has a 1/2000 chance of hitting the red planet but it will pass very close for sure. Should we if we could? It could be the first step in terraforming Mars.

 

[CraigD]

A a dress rehearsal for deflecting a comet from Earth do we currently have the ability to affect the course of this comet so it actually hits Mars?

I don’t like being downbeat, but practically, I’d say no, we aren’t able to do a space mission like this.

 

Consider NASA’s current “asteroid initiative” (decent infographic here). It’s planned for completion in roughly 2025, and intended to capture and maneuver a 7 m diameter asteroid. Comet 2013 A1 has its closest approach to Mars in Oct 2014, and has a nucleus of at least 1000 m diameter (that well-made NASA video gives a “1 - 3 km” estimate, but other sources give a less certain 1 to 50 km). More daunting, it’s moving at about 56000 m/s relative to Mars, which is pretty far from the delta-V capabilities of any spacecraft to date to rendezvous with using mostly powered maneuvering, so a doable mission would, I expect, need to use a complicated plan involving gravity slingshots from one or more of the giant planets, which isn’t doable in time for Oct 2014.

 

That’s just a sketch of the engineering challenges of deflecting a comet. There are also political ones. A search on “NASA asteroid capture” found NASA Asteroid-Capture Plans Draw Faint Praise In U.S. House (22 May 2013), suggesting that actually gaining the necessary approval for even the modest “asteroid initiative” program is politically difficult.

 

Should we if we could? It could be the first step in terraforming Mars.

I’m a space engineering enthusiast, so my first reaction was to answer an enthusiastic yes. Thinking more about impacting a big ice chunk on Mars in 2014, though, I changed my answer to no. I think we need more time to do better research on the pristine Martian surface before kicking up the huge, hot, slightly damp mess of dust such an impact would cause.

 

I hope we humans someday are able to routinely wet dry worlds with comets, but think we’ve a long way to go in achieving the basic engineering approaches to doing this sort of thing. A rush job in the next 18 months, even if by some incredible political and engineering coup it were possible, strikes me as a bad and silly stunt.