Herschel farewelled with shot into solar orbit
ESA’s Herschel space observatory set against a background image of the Vela C star-forming region
On Monday at 12:25 GMT, the European Space Agency (ESA) executed final shutdown on the Herschel space telescope after shooting it into solar orbit. This shutdown marks the end of Herschel’s successful four-year mission of deep space observation, which was terminated when it ran out of liquid helium in April. Without liquid helium to cool its super-sensitive infrared instrument, Herschel was unable to continue its mission, but it was otherwise fully functional, so ESA took the opportunity to use the probe to carry out technical tests that couldn't be done earlier.
“Normally, our top goal is to maximize scientific return, and we never do anything that might interrupt observations or put the satellite at risk,” says Micha Schmidt, Herschel’s Spacecraft Operations Manager. “But the end of science meant we had a sophisticated spacecraft at our disposal on which we could conduct technical testing and validate techniques, software and the functionality of systems that are going to be reused on future spacecraft. This was a major bonus for us.”
Once these tests were completed, Herschel was put through a series of flight control activities and thruster maneuvers, which moved it out of its position at the Lagrangian point L2 1,500,000 km (930,000 mi) from Earth. Its final maneuver was executed on May 13 to 14 when it exhausted its fuel tanks in a record 7-hour, 45-minute thruster burn. This sent the craft into a heliocentric orbit before being completely turned off.
Though deactivated, Herschel’s solar power cells are still charging its batteries, so it could be restarted by a command from Earth, though ESA has no intentions to do so.
The video below shows the construction of Herschel.
About the Author
David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past.
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Why not position it close to the ISS and have them resupply its helium supply? What a waste of money
We really do need a way to do logistics resupply on orbit. I imagine a mission to carry helium and fuel to a large functional satellite is far cheaper than replacing the satellite.
We seem to be getting on-orbit equipment lifetimes far in excess of design life these days. And I know that many modern satellites have grapple fixtures and resupply ports on them as a just in case measure for when someone provides the technology.
DARPA seems to be studying ways to salvage parts off satellites to make new ones on orbit. I think the money would be better spent figuring out how to simply resupply functioning satellites that have run out of expendable resources.
Rocky, it's orbit was nowhere remotely close to the ISS. It was at the Lagrangian point where the gravity of the earth, moon and sun balance out. The probe was never intended to last beyond 2013 and didn't carry enough fuel to return to earth orbit.
They would never have the fuel to get all the way to the ISS and then back out to where it is useful. ISS isn't actually very far from Earth.
ISS - 370km from Earth
Herschel - 1,500,00km from Earth - or 3,000,000 km round trip
It's actually more complicated than that because ISS is in orbit around Earth while Herschel is in orbit around sun.
If you review the data you see that a refueling trip to ISS would not be that implausible. The trip to L2 point took only 60 days so it wold have been an 4 months round trip. The satellite still had fuel for a record 7-hour, 45-minute thruster burn, maybe enough tor the trip back. As of 2010, the Herschel mission is estimated to cost €1,100 million, therefore it was worth to try to make it's usable file longer, look at Voyager 1 and 2. If they are nor pressed by commercial factors, scientist are doing a sloppy work, why not, they will request and receive more funding for the replacement.
Making use of the ISS to resupply satellites looks like a very good idea.
Granted Herschel was a long way away, but it had lots of fuel and after all there's no drag up there to slow it down, so as long as it could actually begin to move in the right direction surely it could have reached the ISS eventually?
Once there all of its systems could have been overhauled and resupplied, including said fuel tanks.
So come on ESA, why didn't you do that?
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