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Mission Complete! WMAP In 'Graveyard Orbit'
astroengine writes "The Wilkinson Microwave Anisotropy Probe (WMAP) has, quite literally, changed our view of the Universe. And after nine years of mapping the slight temperature variations in the cosmic microwave background (CMB) radiation, its job is done and NASA has commanded the probe to fire itself into a 'graveyard orbit' around the sun. WMAP measured the most precise age of the universe (13.75 billion years), discovered more evidence supporting dark energy and dark matter theories, and found one or two mysteries along the way."
It would be very expensive to do so. The probe would have to lose a massive amount of momentum for its orbit to decay far enough for it to pass through the Sun.
They could just as well send it plunging to burn up in Earth's atmosphere. It actually takes more energy to send it on a safe Earth-bound trajectory, and a lot more to send it on a sun-bound trajectory, than it does to move to a graveyard orbit higher up. That way they can keep running the satellite until it's fuel tank is closer to empty.
So Dark Matter was a theory invented to explain why stars orbit a galaxy's core like they were on spokes around the hub of a wheel ...instead of how we observe the motion of object orbiting our sun. So if Dark Matter exerts such a huge force to keep huge objects (stars) moving in such a manner, how come that same force doesn't affect the objects going around the star? Or, in other words, if it's powerful enough to keep the outer-most stars in a galaxy moving in the same period as inner stars, how come we can't detect it here? Or have we detected such tidal forces already?
While there's a lot of dark matter in a galaxy compared to "normal" matter, it's typically spread out over a much larger volume than the viewable parts of a galaxy. Thus, it is actually quite diffuse and has very little effect within something on the scale of a solar system (to the point of being unmeasurable with current technology).
If there's some clumsy PR, it seems to be in other part of TFS. WMAP has not ,"quite literally, changed our view of the Universe" - it further refined it nicely, continuing in the footsteps (if mentioning only large space experiments) of COBE and RELIKT-1 (the latter might be one sad example of another type of clumsy PR - apparently already gave us large part of the results for which COBE is praised, but...)
One that hath name thou can not otter
The dark matter halo around our galaxy is theorized roughly as a large sphere, not just extra mass along the flattened wheel of the spiral. Look at the graphic here: http://startswithabang.com/?p=656
That's a lot of extra room. So much so that even when those researchers calculated that our solar system should have 300 times the dark matter density compared to the galactic dark matter halo, this only ends up being a very tiny fraction of the earth's mass in dark matter bound to our solar system. See: http://www.universetoday.com/15266/dark-matter-is-denser-in-the-solar-system/
So basically, it's going to be rather difficult to detect dark matter nearby.
The prior orbit was at the L2 point http://en.wikipedia.org/wiki/Lagrangian_point#L2 one of the very few stable points in the solar system. Leaving WMAP there would be a bad idea because it makes a very nice spot become more hazardous. We're already having serious trouble with spacejunk in Earth orbit. There's no good reason to star trashing up the rest of the system also.
It would be very expensive to do so. The probe would have to lose a massive amount of momentum for its orbit to decay far enough for it to pass through the Sun.
I see now that WMAP is at an L2 point, whereas I had naively/foolishly assumed it was at an L3 point.
"I don't know, therefore Aliens" Wafflebox1
The orbit was *around* L2, not at L2. The orbit around L2 appears as loops with an apreciable extension wrt to the Earth-L2 distance.
The paradox is that L2 is actually unstable, but orbits can be found around L2 which are stable over a sufficiently long time.
It's not the light emissions of baryonic matter that causes the clouds to collapse, it's the collisions of the 'conventional' matter particles with each other that cause those emissions in the first place. Dark matter on the other hand is thought to interact so weekly with itself that it won't cause a collapse of the dark matter cloud.
I concur, and a favorite comic springs to mind:
Science: It works, bitches
From the wikipedia page about the CMB:
Two of the greatest successes of the big bang theory are its prediction of its almost perfect black body spectrum and its detailed prediction of the anisotropies in the cosmic microwave background.
When basically the whole observable universe matches your theory, it's generally considered pretty strong evidence that you're going in the right direction.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
You've misunderstood the difference between doubting a theory and doubting an observable. Walking off a cliff would be stupid, it it clearly observed that things fall. On the other hand doubting that the reason is due to the attraction of masses, perhaps in favour of some alternative source of the force, does not lead to such stupid mistakes.
The original poster did not contradict the evidence for the big bang, rather the explanation.
And that's why it has to be moved to a retirement orbit. The fuel will run out soon and left where it was it would wander off into some unpredictable and perhaps inconvenient orbit, possibly cluttering up the L2 region and making it hard to use it for anything else. This way it's in a known, out-of-the-way orbit.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
The original poster did not contradict the evidence for the big bang, rather the explanation.
The CMB *IS* part of the evidence for the Big Bang.
The CMB is the afterglow - of a very consistent temperature produced by the Big Bang. This explanation is greatly oversimplified: The Universe being very compact in the past resulting in a uniform distribution of energy at the point at which it went from being opaque to translucent is the only good explanation we have for a uniform glow in all directions.
WMAP mapped the very minor variations in the CMB that tell us about conditions at the point in time when the universe had cooled enough to allow light to travel freely. It tells us a little about what conditions were like at that time and you can calculate what must be the age of the Universe based on this variation. (Yes some assumptions do need to be made, but our modelling has gotten good enough for scientists to be very confident about the age of the Universe).
Why do people insist on talking garbage about things they clearly know nothing about?
These posts express my own personal views, not those of my employer
More accurately, CMB is an observation we have made that is currently best explained by the Big Bang theory.