Dec 30 2014

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MESSENGER on fumes

Literally…er…Figuratively. Whatever. It’s almost completely out of propellant, but they’re going to use the Helium left in the tanks to provide a few more orbit corrections, extending the life of the mission another 3 or 4 weeks.

“To my knowledge this is the first time that helium pressurant has been intentionally used as a cold-gas propellant through hydrazine thrusters. These engines are not optimized to use pressurized gas as a propellant source. They have flow restrictors and orifices for hydrazine that reduce the feed pressure, hampering performance compared with actual cold-gas engines, which are little more than valves with a nozzle.”

“Propellant, though a consumable, is usually not the limiting life factor on a spacecraft, as generally something else goes wrong first,” he continued. “As such, we had to become creative with what we had available.

“Helium, with its low atomic weight, is preferred as a pressurant because it’s light, but rarely as a cold gas propellant, because its low mass doesn’t get you much bang for your buck.”

JPL engineers…is there nothing they can’t do?

Permanent link to this article: http://www.newspaceraces.com/2014/12/30/messenger-on-fumes/

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