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NASA's MESSENGER Mission To Crash Into Mercury In 2 Weeks
astroengine writes: NASA's MESSENGER spacecraft is in the final days of an unprecedented and unexpectedly long-lived, close-up study of the innermost planet of the solar system, with a crashing finale expected in two weeks. Out of fuel, the robotic Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, probe on April 30 will succumb to the gravitational pull of this strange world that has been its home since March 2011. The purpose of the mission, originally designed to last one year, is to collect detailed geochemical and other data that will help scientists piece together of how Mercury formed and evolved. "MESSENGER is going to create a new crater on Mercury sometime in the near future ... let's not be sad about that," NASA associate administrator John Grunsfeld said Thursday.
The Johns Hopkins Applied Physics Laboratory has an excellent site for looking through the pictures MESSENGER has taken and the science it's done.
things crashed into it.
Can we take a second and thank the person who came up with the fantastic backronym "Mercury Surface, Space Environment, Geochemistry and Ranging" for MESSENGER.
For those that don't know, Mercury was the messenger of the Gods.
Don't blame the MESSENGER for crashing into Mercury.
I love reading about this stuff. Space has always been something that amazes me. It will be awesome to see what the future holds as we learn more about what is out there.
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=2&gallery_id=2&image_id=1357
Turns out the boys at NASA have a sense of humor too.
I wish people, including the official NASA press release would quit using this misleading terminology.
A spacecraft only needs fuel to "fight gravity" when changing orbits. In this case, although Mercury doesn't have much of an atmosphere, it does have one, and that's what's dragging the spacecraft down.
When will people stop talking about gravity is it it is in a struggle with object X and eventually it wins. People constantly talk about "Black Holes" sucking in, "inevitable"....
MESSENGER did NOT run out of fuel and SUCCUMB to the gravitation pull of Mercury. Mercury ran out of fuel and continued on it's gravitationally influenced trajectory which was chosen to crash it. they could have left it in an eternal orbit if they wanted too - and the journalist would probably say it "did not succumb" to gravity - which is equally nonsensical. Gravity did not some get the upper hand because this spacecraft ran out of fuel. That craft will always be influenced by Mercury's gravity, no matter how many fragments it smashes into, unless a fragment gets an upwards speed of more than 4.3km/s, in which case it will ESCAPE Mercury's gravity.
I think in this case it might well be gravity. We still haven't sufficiently solved the three body problem to the point where we can predict and hence establish stable orbits with perfection. And the sun is a mighty powerful third body where that hot marble is rolling.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Correction: "future contracts"
Table-ized A.I.
When I first read a snippet somewhere they talked about it crashing. I thought, wow that's not good. Then I read further and find out that's what NASA wants to happen. Its interesting that more talk about finding life elsewhere is creeping into space news. Personally I think its already happened as far as proof that life existed other then on Earth. The question is, how to break it to the public that's acceptable given all the religious ramifications, the questions to follow on who, what and where, when. I believe Earth had help from Alien life thousands of years ago. They may have helped steamroll us into a faster evolution. No doubt plenty of more recent evidence of some sort of monitoring going on. Plenty of UFO sightings going back decades. Its really about time we entertain the reality that we are not alone. I am OK with that as long as they are friendly.
Normally I would agree with you on how gravity gets represented and how in a lot of situations you can replace a body with the same mass black hole with no changes (although get close enough, and things do change, e.g. innermost stable orbit).
However, in this case the problem is gravity. The primary cause of orbital decay for MESSENGER is the Kozai mechanism, which is a three body interaction between the Sun, Mercury, and the probe, causing the probe's orbit to increase in eccentricity until it hits the surface. They had to keep using fuel to keep the eccentricity reasonable, especially considering it is in a pretty low orbit.
Mercury has virtually no atmosphere, even with stuff from the Sun there is no atmospheric drag on the relevant timescales. As others point out, there is a three body physics effect here, in particular, it is the Kozai effect that makes the orbit eventually intersect the surface using just gravity alone.
I can't blame people for modding the comment up, because of how much movies and some journalists get wrong with gravity. But in this case the statement came from the actual scientists and people on the project, because it is actually gravity in this case causing orbital decay. It isn't just from Mercury, but from the Sun being so near that three-body instabilities are much larger. Other comment(s) above explain in a little more detail already.
Interesting. So does the Kozai effect explains why Mercury (and maybe Venus) doesn't have any moons, unlike (say) Mars, which is presumably too far away from the perturber Sun? (Or maybe Phobos and Deimos entered Martian orbit too recently for the Kozai effect to have, well, taken effect.)
Ok, reading further about the Kozai mechanism (http://www.orbitsimulator.com/gravity/articles/kozai.html), apparently it's only relevant to satellites that have (roughly) non-equatorial orbits. So I suppose if Messenger (or a natural moon of Mercury) were in an equatorial orbit, it would be (more) stable, right? (The formula they give implies zero eccentricity at an inclination of about 39 degrees. The formula gives an imaginary number if the inclination is less than that; I'm not sure what an imaginary number means in that context.)
It is not so much an equatorial orbit, but an orbit that is in the same plane as the movement of the more distant object, i.e. the Sun in this case. It can be more complicated when there are other objects not too far away, as then you might find there is no common plane. It is also possible to be far enough away from the planet and with a low enough combination of eccentricity & inclination such that you can complete the whole oscillation period without hitting the planet.