How Spitzer Has Stayed Alive for So Long

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How Spitzer Has Stayed Alive for So Long

Post by bystander » Sat Jun 15, 2019 3:12 pm

How Spitzer Has Stayed Alive for So Long
NASA | JPL-Caltech | Spitzer | 2019 Jun 13
After nearly 16 years of exploring the cosmos in infrared light, NASA's Spitzer Space Telescope will be switched off permanently on Jan. 30, 2020. By then, the spacecraft will have operated for more than 11 years beyond its prime mission, thanks to the Spitzer engineering team's ability to address unique challenges as the telescope slips farther and farther from Earth.

Managed and operated by NASA's Jet Propulsion Laboratory in Pasadena, California, Spitzer is a small but transformational observatory. It captures infrared light, which is often emitted by "warm" objects that aren't quite hot enough to radiate visible light. Spitzer has lifted the veil on hidden objects in nearly every corner of the universe, from a new ring around Saturn to observations of some of the most distant galaxies known. It has spied stars in every stage of life, mapped our home galaxy, captured gorgeous images of nebulas and probed newly discovered planets orbiting distant stars.

But as Spitzer's deputy mission manager, Joseph Hunt, said, "You can have a world-class spacecraft, but it doesn't mean anything if you can't get the data back home."

Spitzer orbits the Sun on a path similar to Earth's but moves slightly slower. Today it trails about 158 million miles (254 million kilometers) behind our planet - more than 600 times the distance between Earth and the Moon. That distance, along with the curve of Spitzer's orbit, means that when the spacecraft points its fixed antenna at Earth to download data or receive commands, its solar panels tilt away from the Sun. During those periods, the spacecraft must rely on a combination of solar power and battery power to operate.

The angle at which the panels point away from the Sun has increased every year that the mission has been operating. These days, to communicate with Earth, Spitzer has to position its panels at a 53-degree angle away from the Sun (90 degrees would be fully facing away), even though the mission planners never intended for it to tilt more than 30 degrees from the Sun. Spitzer can communicate with Earth for about 2.5 hours before it has to turn its solar panels back toward the Sun to recharge its batteries. That communications window would grow shorter year after year if Spitzer continued operating, which means there is a limit to how long it would be possible to operate the spacecraft efficiently. ...
Know the quiet place within your heart and touch the rainbow of possibility; be
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