NASA aims for Friday WISE up
Wide-field Infrared Survey Explorer set for launch
NASA's Wide-field Infrared Survey Explorer, aka WISE, is scheduled to blast off on Friday from Vandenberg Air Force Base in California on its mission to "scan the entire sky in infrared light with a sensitivity hundreds of times greater than ever before".
All being well, WISE will be carried aloft atop a Delta II rocket during a launch window stretching from 14:09 to 14:23 GMT. Once it reaches its working orbit of 500 km, it will set about its six-month mission to capture 1,500,000 images which will offer a "cosmic clearinghouse of hundreds of millions of objects that will be catalogued and provide a vast storehouse of knowledge about the solar system, the Milky Way, and the universe".
Specifically, WISE will "uncover objects never seen before, including the coolest stars, the universe's most luminous galaxies and some of the darkest near-Earth asteroids and comets".*
To do this, it's carrying a 40-centimetre-diameter (16-inch) telescope and four one million-pixel infrared detectors, all packed in a frozen-hydrogen-filled cryostat designed to keep the instruments at 12 Kelvin (-261°C).
The whole package (seen above with solar panel at right) is described by NASA as resembling "a giant Thermos bottle" or "the Star Wars robot R2-D2", and being "about the height and weight of a big polar bear, only wider".
For those of you who prefer standard units, it's "2.85 meters tall (9.35 feet), 2 meters wide (6.56 feet), 1.73 meters deep (5.68 feet) and weighs 661 kilograms (1,433 pounds)".
* In a minor Bruce-Willis-alert moment, NASA says of asteroids and comets:
The mission is expected to find hundreds of these bodies, and hundreds of thousands of additional asteroids in our solar system's main asteroid belt. By measuring the objects' infrared light, astronomers will get the first good estimate of the size distribution of the asteroid population. This information will tell us approximately how often Earth can expect an encounter with a potentially hazardous asteroid.
WIRE is a nice sidelight on Hydrogen
Note that the sunlight *reflected* off the Earth was enough to vaporise *solid* hydrogen and spin it up to 60rpm
This is a few pc (IIRC) of what the sun actually emits onto the earth and a reminder that planning an H2 powered vehicle (beloved of Top Gear presenters) had better have either very strong (5000 psi) tanks or *very* good insulation as the volume change of LH2 to GH2 is about 1:700. If that does not worry advocates of this wonder fuel they should look up the phrase "fuel air explosive" along with "ignition temperature" and "explosive mixture limits"
IT Angle. The root cause was the pyro system used an Actmel FPGA to lower hadware package count, weight, volume etc. Turns out the I/O definitions and status are unreliable until for a while after power up. Some outputs (or inputs) normally putting out 0 (or 1) might put out their reverse. Bad news if one of those O/Ps was wired to a pyro device and went 1 (fire) when it had not been told to.
NB AFAIK this is not unique to Actmel parts but they are space rated and are one time programmable so don't need a seperate ROM to configure their on chip SRAM tables. Just one of those little differences between the EDA sim of a part andd real life.
It's thanks to things like this that you have a DSLR.
The first CMOS arrays ( the replacment for CCDs in most cameras) really got good for the infrared camera on Hubble.
About 15years ago they made a 1000x1000 array which cost $100K (with a 1-2um infrared sensor layer) and had noise comparable to a CCD.
1 MP camera at 22um is very very impressive at any price!
"for the zillions of my tax dollars this no doubt cost, they couldn't do better than a 4MP camera (more accurately 4x 1MP, which might be even worse)."
No doubt. Except your camera sensor works at 0.3-0.85microns, not the 3.4, 4.6, 12 and 22 microns this system is designed to see. They were built by Teledyne (who probably build by the 100s, or a couple of 1000 sensors a year). They can take about 8g and the odd soar flare or 2 and their packageing is designed to survive about -253c (-398F or thereabouts). NASA state WISE's last working predecessor sat (IAS) had 62 pixel sensors (presumably a scanning mirror to sweep the scene).
Those sensors will be susbstantally more expensive than the biggest SLR camera sensor.
And this wills tive give about a 60 fold improvement over what is already known.