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Chandra flies 200 times higher than Hubble - more than 1/3 of the way to the moon! |
For the planned operational orbit of Chandra, the closest approach to Earth and the most distant point from Earth will be as follows:
Altitude at Perigee (closest approach) = 10,000 km = 6,214 (statute) mile = 5,400 nautical mile
Altitude at Apogee (most distant point from Earth) = 140,000 km = 86,992 (statute) mile = 75,594 nautical mile
For reference, Mean radius of Earth = 6,371 km = 3,959 (statute) mile = 3,440 nautical mile |
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Chandra can observe X-rays from clouds of gas so vast that it takes light five million years to go from one side to the
other! |
If we assume conservatively that a cluster extends out to a radius of 1 Mpc, then it has a diameter of 2 Mpc, or 6 million light years. |
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During maneuvers from one target to the next, Chandra slews more slowly than the minute hand on a clock. |
According the CXC Observatory Guide, it takes Chandra 31 minutes to slew 90 degrees. It takes the minute hand on a clock 15 minutes to slew 90 degrees. |
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At 45 feet long, Chandra is the largest satellite the shuttle has ever launched. |
For comparison, the Hubble Space Telescope was just over 43 feet long. |
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If Colorado were as smooth as Chandra's mirrors, Pikes Peak would be less than one inch tall! |
Numbers:
Assume optics size = 84 cm
Assume rms low frequency figure errors are < 100a = 1e-6 cm
Assume size of Colorado= 600 km = 6 E7 cm
Then the ratio of the (rms errors)/(optics size) < 1.2 e-8
Assuming that there will be one 3 sigma peak in 1000 trials (the approx.
number of measurements of the figure), then the ratio is < 3.6e-8.
Then the largest mountain (which is not Pikes Peak, but is not much taller than Pikes Peak) in Colorado would be < 2.2 cm < 1 inch. |
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Chandra's resolving power is equivalent to the ability to read a stop sign at a distance of twelve miles. |
The letters on a stop sign are 25 cm high. Assuming that we need a 5 x 5 pixel square, then the resolution element is 5 cm high, which would subtend an angle = 0.5 arcsec at a distance D = 5/2.5E-6 = 2 E6 cm = 20 km = 12 miles. |
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The electrical power required to operate the Chandra spacecraft and instruments is 2 kilowatts, about the same power as a hair dryer. |
A standard hair dryer uses 1600-1800 watts (slightly less than 2 kilowatts) on its high setting. |
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The light from some of the quasars observed by Chandra will have been traveling through space for ten billion years. |
If we take a Hubble constant of 60 km/sec-Mpc, then the Hubble time is approx 16 billion years, so for a quasar at z>3, the look back time, depending on Omega, is greater than 10 billion years. |
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STS-93, the space mission that deployed Chandra, was the first NASA shuttle mission commanded by a woman. |
Commander Eileen Collins was the first woman to command a NASA shuttle mission. |
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Chandra can observe X-rays from particles up to the last second before they fall into a black hole!!! |
The last stable orbit for a Schwarzchild metric is 6GM/c^2 ~ 10^7 cm for a 10 solar mass black hole. The time to fall in from this point on is ~ 0.001-.01 seconds, depending |
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