Slashdot Mirror
NASA Spacecraft Set to Shine Spotlight on Mercury
coondoggie writes to tell us Network World is reporting that NASA will this month see the realization of a mission launched in 2004, sent to explore the planet Mercury. "MESSENGER, launched in 2004, is the first NASA mission sent to orbit Mercury, the planet closest to the sun. But on Jan. 14 it will pass close by the planet and use Mercury's gravity for a critical assist needed to keep the spacecraft on track for its ultimate orbit around the planet three years from now. Still, the spacecraft is also expected to throw back some never-before -seen images, NASA said. The flyby also will gather essential data for planning the overall mission. After flybys of Earth, Venus, and Mercury, it will start a year-long orbital study of Mercury in March 2011, NASA said. "
They'll have to land and go inside the caves if they want to find the harmoniums.
Tags != Comments, and -1 (Troll) != -1 (I Would Respond Angrily To This Poster So They Must Be Trolling)
Sirens of Titan.
Must be weird living on a planet where the day (=159 Earth days) is longer than it's year (59 Earth days)
..........FULL STOP.
>> NASA Spacecraft Set to Shine Spotlight on Mercury
Why does this make me think police helicopter?
Bad boys bad boys
Watcha gonna do, whatcha gonna do
when they come for you
It's hinted at in the story, but the reason the probe is taking its sweet time to actually achieve an orbit is Mercury's high orbital velocity.
It's pretty easy to get into an elliptical orbit which stretches from Earth's orbit around the Sun to Mercury's orbit around the sun. But getting into a circular orbit means matching Mercury's velocity, and doing so in a way that lets a "burn" be made to actually enter into an orbit around the planet. As I recall, you need a total velocity change of 40 kps to get into orbit around Mercury. That more than twice the change required to get into an orbit around Mars.
It's pretty impressive that NASA figured out a way to do this with a gravity assist. A proposed European probe would have used an ion rocket to make the velocity change.
Here is the actual JPL page for the mission. It's updated every day.
Check the mission pics on the left side as there are some preliminary pics of mercury. They are still a bit blurry.
NASA Spacecraft Set to Shine Spotlight on Mercury
Hint: Mercury is shiny.
The theory of relativity doesn't work right in Arkansas.
Am I the only Slashdotter who looked at this and thought, "Of course they've never been seen, they haven't even been taken yet." Yes, yes, I know what they meant, but couldn't they have said what they meant instead of something dramatic but wrong?
OK, folks, see if you can manage to mod me down with a -1 Pedant, now.
Good, inexpensive web hosting
I can't imagine they'd need any more light on Mercury, what with the sun just 36 million miles off and all.
Nice alliteration, btw.
!#@%*)anks for hanging up the phone, dear.
How many candlepower must that spotlight be? Nuclear powered? Would it really light things up much more than the sunlight?
Poor choice of a metaphor in the heading; had me thinking there was some illumination involved.
Love many, trust a few, do harm to none.
Here's a picture of me when I was younger......
ALL PICTURES OF YOU ARE OF YOU WHEN YOU WERE YOUNGER.
Heres a picture of me when i'm older....
You son of a bitch, where did you get that camera?
Ah, how i wish Mitch was still rambling.
Ice Cream has no bones.
NSFW!
Scam redirect!
Gay male porn video link in parent!
Mercuries rotation is synchronized with its' orbit in such a fashion that the same portion always faces towards/away from the sun.
You know, there's a reason why most of us don't trust URL redirector links posted on Slashdot. Still, I'm disappointed. The traditional target for these links is Goatse.
"They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
I thought it was in a 3:2 ratio. The Moon is locked in a 1:1 ratio with the Earth, but I don't think Mercury has a 1:1 ratio with the Sun.
I don't trust them either, but I'm often curious and nobody's going to fire me for opening them on this system. It sometimes entertains me to see what the trolls are linking and if I can help keep someone from losing a job by clicking absentmindedly, I think it's all worth it.
That's hot.
Me too, unfortunately I clicked on this one.. :(
Looks like you did too.
Gone!
All your 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 are belong to us
+0 Meh
"http://www.jpl.nasa.gov/missions/past/mariner10.html"
It was also the first mission to use a gravity assist. At the time of launch the rotation period of Mercury was unknown. By an amazing coincidence, every pass of the spacecraft photographed the SAME FACE of the planet, as its rotation period matched exactly the interval of Mariner 10's return.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
Correct! Take a look at this.
Similar to the upcoming US election results
It makes a big difference as a Mercury year is 88 earth days, nearly half of that time it is our of site behind the sun.
Mercuries rotation is synchronized with its' orbit in such a fashion that the same portion always faces towards/away from the sun.
http://www.enchantedlearning.com/subjects/astronomy/planets/mercury/
"Until 1962 it was thought that Mercury's "day" was the same length as its "year" so as to keep that same face to the Sun much as the Moon does to the Earth. But this was shown to be false in 1965 by doppler radar observations. It is now known that Mercury rotates three times in two of its years. Mercury is the only body in the solar system known to have an orbital/rotational resonance with a ratio other than 1:1 (though many have no resonances at all)."
The truth shall set you free!
> is the first NASA mission sent to orbit Mercury
Well it may be the first to technically orbit Mercury, but
Mariner 10 used a Solar orbit to swing-past Mercury three
times.
http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1973-085A
It was also the first probe to use plentary gravity assistance,
in this case Venus, to change course. La plus ca change...
Imagery here:
http://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/MC_Mariner_10_page1.html
...on Jan. 14 it will pass close by the planet and use Mercury's gravity for a critical assist needed to keep the spacecraft on track for its ultimate orbit around the planet three years from now. ... I'm dumbfounded. How do they design these complex trajectories? It's actually quite easy! All you need is spice. A Mentat or two may also come in handy.With the first link, the chain is forged.
Hmm.. as a gyno, the man made a nice living dealing with pussies and getting comfortable with assholes.
Looking at his supportards, that now makes all the sense in the world...
I think you have a good question. See, here on Earth when we go somewhere through a trackless waste -- e.g. we sail somewhere on a ship -- we can figure out where we are simply by knowing our orientation (attitude) with respect to the fixed stars, which we do with sextant and chronometer. Since we live on the surface of a sphere, attitude (e.g. latitude and longitude) is all we need to know to know where we are.
In space, it's equally easy to figure your attitude from the fixed (i.e. distant) stars. So attitude is no problem. However, what you also want to know in deep space is the translational distance of your coordinate origin from, e.g. that of your starting point, e.g. Earth. That's pretty important stuff! That is, it's not enough to know that galactic North is this way, and if you look over there you're looking at the Sun. You'd also want to know -- probably very much! -- how far away the Sun is in that direction. If nothing else, that's going to determine how long you accelerate and when you plan to start decelerating. Don't want to overshoot or undershoot, right? Probably pretty expensive, even if it doesn't leave you fuel-less and marooned in interstellar space...
Now if you go large distances, a few thousand light-years or so, then of course the pattern of stars will shift around you, and if you have a good 3D map of the galaxy, you can triangulate and determine where you are. This would be like ship navigation by triangulating on landmarks when you are close to shore.
But what if you don't? What if, as seems more likely, you go 5-10 light years? Over that distance, the pattern of stars is going to change very little, if at all, simply because stars are so bloody far apart on average. So how good is your triangulation navigation going to be? Especially if, as happens to be the case presently, our knowledge of the exact 3D location of nearby stars is a bit spotty. It would be like navigating at sea by trying to measure the changes in how the surface of the Moon looks from different positions, made worse by not having a terribly good map of the Moon's surface to begin with.
I suppose one answer is just inertial navigation. Your trajectory in deep space is likely to be affected only by your own self-acceleration (which you can measure very accurately) plus the gravity of your source and destination stars, which you hopefully have measured before you set out, plus the average gravity of the galaxy in your neighborhood, which is hopefully pretty constant. God help you if you pass too close to an uncharted brown dwarf, however, and it's worth noting that there are probably thousands of these "hidden reefs" still undetected in the Sun's immediate neighborhood.