[Solarsail]

I'm pretty sure that was Steve Squyres in the book Roving Mars, discussing Spirit and Opportunity. From memory, a heat shield can get you from escape velocity down to ~mach 3, and then supersonic parachutes can get you down to ~100mph. It's an issue because you've still got to slow down beyond that, but you can't just ignore atmospheric shielding like you could with the Moon (in response to iwwr)

I could be wrong about him saying that in Roving Mars (I can't exactly grep my paperback copy, and Google isn't helping), but I'm pretty sure it wasn't on the subject of Curiosity... I heard it in 2006 or 2007, while Curiosity was still called the Mars Science Laboratory.