From the JPL:
Mars Tugging on Approaching NASA Rover Curiosity
August 04, 2012
PASADENA, Calif. – The gravitational tug of Mars is now pulling NASA’s car-size geochemistry laboratory, Curiosity, in for a suspenseful landing in less than 40 hours. [About 35 as I write.]
“After flying more than eight months and 350 million miles since launch, the Mars Science Laboratory spacecraft is now right on target to fly through the eye of the needle that is our target at the top of the Mars atmosphere,” said Mission Manager Arthur Amador of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
The spacecraft is healthy and on course for delivering the mission’s Curiosity rover close to a Martian mountain at 10:31 p.m. Sunday, Aug. 5 PDT (1:31 a.m. Monday, Aug. 6 EDT). That’s the time a signal confirming safe landing could reach Earth, give or take about a minute for the spacecraft’s adjustments to sense changeable atmospheric conditions.
The only way a safe-landing confirmation can arrive during that first opportunity is via a relay by NASA’s Mars Odyssey orbiter. Curiosity will not be communicating directly with Earth as it lands, because Earth will set beneath the Martian horizon from Curiosity’s perspective about two minutes before the landing.
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Read the rest there.
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I hope they pull it off. That skycrane contraption that they’re using for this landing has me worried. It’s hard enough to get a probe to Mars in good working order (see these 8 failures, for example) that I fear a failure in some part of that landing system. So many things have to work absolutely perfectly, and there’s no chance to go around and try again. Having said that, if the landing system works, that probe should be able to do some great science over the next few years.
Those of you who follow the American space program will enjoy this preview of coming attractions: SpaceX’s Dragon to Return Americans to Space.
I viewed this video about twenty minutes after the email from SpaceX was sent out, when it had been seen about 360 times. About thirty hours later, the view count is 13,846. I really like the gesture made by two astronauts at 2:09.
Boldly Opening a New Window Onto Mars, by John Grotzinger, chief scientist for the Mars Science Laboratory mission, who writes:
I am usually so deep into mission planning that I tend to become immersed in all the arcane details of learning how to operate the rover on the surface of Mars. Imagine buying a $2.5 billion car with a 10,000-page owner’s manual; one that you don’t just have to read but you must also write, because it’s the first and only one that will ever be made.
“…Gravity of Mars is now pulling Curiosity.”
The gravitational constant is universal; as the distance between two objects approaches infinity the gravitational force they exert on each other approaches zero. As such, the gravity of Mars was always pulling Curiosity from the moment there first was Curiosity. Also, if Einstein is correct about spacetime, then the speck of dust on your nose is deforming the spacetime of the entire universe. All, of course, to such a tiny extent as to be immeasureable in practical terms; but the math says it’s something, not nothing.
(I never miss an oppotunity to point this out. Certainly, it’s something even more when the gravity of the target planet is factored into the approach and possibly even is used for some factor instead of the force from rockets that would otherwise have adjusted the flightpath. I’m just too nerdy, however unthorough and slapdash my nerdy knowledge may be, not to point out that you and I sitting on Earth are also experiencing the force of Mars’s gravity, just too little to notice.)
The Cobbler,
Fr Z didn’t say there was no gravitational force on Curiosity before but rather that such gravitational force had not been pulling the ship towards Mars, i.e., that it was being neutralized by other gravitational forces from other directions.
Apologies to Newton, but Einstein’s understanding of gravitation makes much more cosmological sense to me.
robtbrown,
Stop me if I’m wrong, but I figure that the movement is an effect, while the pull — at least, what I would have thought would be called the pull — is the force, the cause, which may be there even if the effect is merely to add to or subtract from its weight against the Earth.
And I’m not clear where Einstein and Newton conflict on this matter; I thought Newton got down the general math at various levels (movement, acceleration, force, energy) but Einstein dug into the nature of matter’s relationships that we call time and space and noted a few special effects following from that but not invalidating the general physics of Newton.
Then again, I’m not a physicist, just a kid who was interested in it at one time. Well, still am interested, but less so than other things such that I haven’t got around to reading the Theory of Relativity itself now that I know a few places I should be able to find it.
Where’s ContraMundum (the physics prof) when we need him. LOL
The Cobbler says:
Stop me if I’m wrong, but I figure that the movement is an effect, while the pull — at least, what I would have thought would be called the pull — is the force, the cause, which may be there even if the effect is merely to add to or subtract from its weight against the Earth.
You seemed to say that Mars was always pulling on the ship. My point is that although there was a force, it wasn’t sufficient enough to pull (or tug) it. As the ship has approached Mars, the force was sufficient to pull it.
And I’m not clear where Einstein and Newton conflict on this matter; I thought Newton got down the general math at various levels (movement, acceleration, force, energy) but Einstein dug into the nature of matter’s relationships that we call time and space and noted a few special effects following from that but not invalidating the general physics of Newton.
I never said they did conflict on this matter.
My interest is in cosmology more than in measurement. Although Newtonian mechanics concern the later, there is nevertheless an implicit cosmology to be found. Generally, my objections to Newton cosmology are two, both of which are part of a static universe: 1) He thought there is absolute Time and Place (space). 2) He has no concept of circular motion (i.e., it is defined in terms of straight line motion).