Comments on: Mars is tugging on NASA Rover Curiosity

By: Gary S

Gary S — Sun, 05 Aug 2012 23:45:11 +0000

@ Ken: Mars is in a higher orbit than Earth is, thus it’s moving SLOWER. But the elliptical orbit which Curiosity is on was faster when near earth and is now SLOWER than Mars. Mars is catching up and also attracting with its gravity. The entry into Mars’ atmosphere at ~ 13,000 mph will need to dissipate a lot of energy (= heat) to equalize their speeds.

By: Greg Laden

Greg Laden — Sun, 05 Aug 2012 23:44:45 +0000

OK, why does curiosity not just enter into a nice little round orbit around mars, like Apollo did at the moon, and take a breather for a while?

By: Ken

Ken — Sun, 05 Aug 2012 14:20:07 +0000

Let me expand on that a bit.

Mars is in a “higher” orbit around the sun than Earth’s orbit, which means it’s a “slower” orbit (takes longer to go around the sun), but is moving faster than Earth in it’s orbit. That means anything transferring from Earth’s orbit around the sun needs to add velocity to catch up to the orbit of Mars around the sun. At that point it will be in a slower orbit around the sun, moving faster than it was when in the same orbit as Earth.

Through all this, it will have an approach speed towards Mars (since that’s the point, of course).

By: Ken

Ken — Sun, 05 Aug 2012 14:03:19 +0000

Remember, both Earth and Mars are moving (in a circular orbit, with a circular transfer orbit). Any speed needs to be figured given relative to one of those planets (or the sun). This isn’t a train leaving New York heading for Chicago in terms of math problems.

By: Greg Laden

Greg Laden — Sat, 04 Aug 2012 23:28:41 +0000

Well, I just hope they have this figured out correctly.

By: como

como — Sat, 04 Aug 2012 23:16:21 +0000

“After flying more than eight months and 350 million miles since launch…”
That is an average of 57,000 mph

“Curiosity was approaching Mars at about 8,000 mph (about 3,600 meters per second) Saturday morning.”
So it has decelerated over the course of the trip, I guess?

By: LC

LC — Sat, 04 Aug 2012 22:05:30 +0000

Several days? And I thought there were just 7 mins. of terror. Have to say that I am glad I’m not a member of the team. I’m not sure I could stand the stress.