Any day now we could lose the Herschel Space Telescope. Wait a minute, you might say. The what?
It’s quite likely you’ve never heard of Herschel, mostly because we’re here in the U.S. and Herschel is a European project. Like Spitzer, Herschel is an infrared telescope, seeking out the faintest heat signatures from beyond all visible light. And like Spitzer it does so by cooling itself to a fraction of a degree above absolute zero. In the infinite entropy of the universe, anything that has even the tiniest bit of a temperature reading can theoretically be detected by Herschel.
So let’s look into that much larger cousin of our beloved Hubble Space Telescope.
NASA contributed some hardware to the telescope which was launched in 2009 and reached its destination about two months later. Herschel parked itself at this marvelous point in space called a Lagrange point, where the gravitational pull of the Earth and the sun balance each other out. Our pal Kepler is using the same principle to stay in one region of space in order to observe the exact same piece of sky over long periods of time.
Herschel has performed splendidly over the past four years; it never made the headlines with catastrophic failures, it just quietly did its thing while scientists all over the planet salivated over the intriguing observations the telescope produced.
What will eventually do it in is the fact that it will run out of super-cooled helium, the stuff that keeps it extremely cold. It simply evaporates over time since its environment is always warmer than the super-cooled helium itself.
Engineers estimate that that day will come sometime this month, and they will know when Herschel’s frigid temperatures will quite suddenly rise by several degrees. Until then, its observation schedule continues at full speed, no doubt creating many nail-biting moments for those scientists who are still lining up to use the telescope for their work, hoping to beat that inevitable event.
There is no gauge on the spacecraft to tell you exactly how much propellant is left, so there might be a bit of wiggle room in that estimate. Extra sensors are costly to install and even costlier to launch, and it’s tricky to measure volumes of gases or liquids in microgravity.
And while observations might cease at any moment the telescope is far from done. When it shuts down it will be moved into a stable solar orbit that will prevent it from crashing into anything, and of course the science data will take many more years to be fully examined and understood.
There’s lots more information at the ESA’s Herschel pages at http://www.esa.int/Our_Activities/Space_Science/Herschel/
Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at firstname.lastname@example.org