NASA WISE Satellite Blasts Into Space

coondoggie writes "After a three day delay, NASA's Wide-field Infrared Survey Explorer this morning blasted into space courtesy of a Delta II rocket and will soon begin bathing the cosmos with infrared light, picking up the glow of hundreds of millions of objects and producing millions of images. The space agency says the WISE spacecraft will circle Earth over the poles, scanning the entire sky one-and-a-half times in nine months. The idea behind the spacecraft is to 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."

Bathing the cosmos with infrared light?

[Grokmoo]

The summary says it will be "bathing the cosmos with infrared light". What is this supposed to mean? The spacecraft will be detecting light, but will not be emitting it in any substantial quantity. In fact, WISE will be emitting very little infrared light at all (even for a spacecraft), as it is being kept cool for the next 10 months or so with an onboard supply of solid hydrogen.

Re:Scan Rate

[Snowblindeye]

Wouldn't that scan complete one sky in 6 months? It's kind of strange to report that it will do 1.5 in 9.

It's because WISE has a limited life expentancy of 10 months. In that 10 months its expected to cover the whole sky 1.5 times.

The life expentancy is only 10 months because the instrument needs to be cooled, which is done with solid hydrogen. Once the hydrogen is gone, the primary mission is over. Not sure if they have a plan for afterwards and can get secondary uses out of it.

Re:Scan Rate

[CityZen]

Ah, I'm wrong. From TFA:

"After a one-month checkout period, WISE will spend six months mapping the whole sky. It will then begin a second scan to uncover even more objects and to look for any changes in the sky that might have occurred since the first survey, according to NASA. This second partial sky survey will end about three months later when the spacecraft's frozen-hydrogen cryogen runs out."

Re:Bathing?

[clone53421]

No. It is a passive device, as you suspect.

However, TFS can’t be entirely blamed for this mistake. It was copied and pasted directly from TFS.

Better article [nasa.gov] – from the horse’s mouth, as it were. Some interesting tibits:

Because the instrument sees the infrared, or heat, signatures of objects, it must be kept at chilly temperatures. Its coldest detectors are less than minus 447 degrees Fahrenheit.

"WISE needs to be colder than the objects it's observing," said Ned Wright of UCLA, the mission's principal investigator. "Now we're ready to see the infrared glow from hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies."

WISE will see the infrared colors of the whole sky with sensitivity and resolution far better than the last infrared sky survey, performed 26 years ago. The space telescope will spend nine months scanning the sky once, then one-half the sky a second time. The primary mission will end when WISE's frozen hydrogen runs out, about 10 months after launch.

Just about everything in the universe glows in infrared, which means the mission will catalog a variety of astronomical targets. Near-Earth asteroids, stars, planet-forming disks and distant galaxies all will be easy for the mission to see. Hundreds of millions of objects will populate the WISE atlas, providing astronomers and other space missions, such as NASA's planned James Webb Space Telescope, with a long-lasting infrared roadmap.

Re:Bathing the cosmos with infrared light?

[clone53421]

"scanning the entire sky one-and-a-half times in nine months" wha...? Why not just say "it will scan the sky in 6 months" (per TFA).

Because it’ll scan the sky in 6 months, then scan about half of it again in 3 months before it runs out of the coolant needed to keep its sensors cold.

In other words, it will scan the entire sky one-and-a-half times in nine months.