February 16, 2020 – Farewell and Thank You to Spitzer

We can’t see in infrared.  For better or worse, our eyes rods and cones just do not have sensitivity to those longish wavelengths of light.  What would we see if we could suddenly see in infrared?  It would be wild!  Everything and anything giving off heat would be glowing, and in infrared warmer means brighter.  Ever see photos taken with infrared sensitive media?  They look eerie, everything glowing, even leaves on trees.  Infrared sensitivity helps mosquitoes find us in the dark and the best spots to bite too.

Life in the infrared would be way different.  Well, we don’t see infrared so that concept is moot, but we have developed equipment sensitive in the infrared spectrum.  Night vision goggles for example are useful for spotting people or critters sneaking around in the dark.  In astronomy the infrared spectrum helps us see stuff that isn’t hot enough to spot otherwise.  Another fun thing about infrared is it can cut through dust so we can detect stuff hidden from optical telescopes.

This is where Spitzer comes in.

Way back in 1946 astrophysicist Lyman Spitzer, Jr. proposed a space-based telescope…years before we had any satellites in orbit!  When NASA was born Spitzer petitioned them to get a telescope in space.  NASA started placing telescopes in orbit on rockets alright, but they weren’t infrared telescopes. The first telescopes/instruments in orbit were for gamma ray, x-ray, and ultraviolet.  When the Space Shuttle program was born and NASA was looking for payloads, you got it, one was a telescope.  In 1990 NASA placed the magnificent Hubble space telescope in orbit via shuttle Discovery.  Hubble still operates today but not much in the infrared.

What’s the big deal about placing an infrared telescope in space?  Heat.  Remember, infrared is heat and the Earth and most everything on Earth generates heat.  Not the ideal place for an infrared telescope.  Too much background noise.  Even so, there are some ground-based telescopes that can study the cosmos in infrared, albeit with much less sensitivity than a space-based telescope.

NASA launched its SIRTF (Space Infrared Telescope Facility) in May 2003, and placed in a heliocentric orbit, not an Earth orbit.  This keeps the telescope far away from Earth’s heat.  Nevertheless, to produce high sensitivity and low noise, the telescope had to be cooled with liquid helium, to a cool 5 degrees K (-450 degrees F).  It has helped astronomers’ study proto-stars, extrasolar planets, life giving molecules in proto-planetary material around young stars, and some of the most distant and oldest galaxies known.

So, what about Spitzer?  SIRTF was re-named Spitzer in December 2003 in his honor.  It ran out of cooling liquid helium in 2009, reducing its sensitivity, and was retired at the end of January 2020.

What’s in the Sky?

February 18; 30 minutes before sunrise; southeast:  Watch the waning crescent Moon get close and even cover up Mars.  Binoculars or telescope helps.