Telescope in the sky

Imagine that you can get your hands on a Boeing 747. What would you do? Well, probably not what NASA did: they cut a 10-by-10 foot hole in the back of the airplane, and installed a big telescope in it.

That is indeedthe SOFIA mission, short for Stratospheric Observatory For Infrared Astronomy and active since 2010. It is a joint collaboration between the US and Germany. And don't worry about the hole... they put back a sliding "door" that weighs over 1,4 tons.



It makes sense indeed, to haul a100 inchtelescope designed for infrared astronomy to a height of more than 40 000 feet, well above most of the water vapor on Earth. And given the temperatures at that height, it helps cooling, too (the telescope bay has to be cooled before take-off to avoid changes in the mirror's shape).

But there is one thing that really impresses me. I have once flown on a Jumbo, and found it behaving like a school bus on a bumpy road. Maybe related to the mountains in Afghanistan or the Caucasus, but even in better conditionsone wonders indeed how they can precisely keep faraway astronomical objects in focus. As Wikipediadescribes it, this is achievedboth by bearings that isolate it from the airplane, and an ingenious "system of gyroscopes, high speedcameras, and magnetic torque motors to compensate for motion". Basically, this ensures that the telescope is locked into the object, even if the airplane around it rocks and rolls (source).

It is indeeda very good way to study infrared objects. Given our atmosphere, most of the infrared light is filteredout, but astronomers rely onit to help study for instancehow stars are created. The airplane, at 330 million dollar build costs, is cheaper than a satellite. And because it returns to Earth after mission, it is easier to service and upgrade scientific instruments. Nice!