Feeds

Grav-mapping satellite fires ion engines

GOCE xenon-fed drives 'performing nominally' says ESA

The smart choice: opportunity from uncertainty

The European Space Agency (ESA) has confirmed that both the electric ion propulsion engines aboard its Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite are "performing nominally".

Artist's impression of GOCE orbiting over ice. Pic: ESAThe "cutting-edge" drives - built by Qinetiq - are designed to compensate for "the tiny amount of drag generated by the few wisps of atmosphere at GOCE's orbital height".

ESA explains: "This cutting-edge system does not burn fuel like a regular rocket motor. Instead, it is supplied with xenon from a 40-kg tank, which is converted to fast-moving ions - naked xenon atoms that have had some of their electrons stripped away by an electric discharge generated from solar energy. The ions are ejected toward the rear, giving a very gentle, steady and smooth thrust."

This thrust represents a "fantastically small force" of between 1 and 20 millinewtons (mN), but that's enough to maintain GOCE's "free-fall" orbit - currently decreasing at a rate of around 190 metres a day from an altitude of roughly 280 km.*

Spacecraft Operations Manager, Juan Piñeiro, said: "On Tuesday last week, we fired the B-unit of the electric ion propulsion, stepping it through 1, 3 and 8.3 mN of thrust. On Thursday, we fired the A-unit. Both are performing nominally."

All being well, the engines will - as part of the Drag-Free and Attitude Control Subsystem (DFACS) - automatically maintain GOCE's velocity and altitude while the scientists get down to the job in hand.

GOCE Mission Manager, Rune Floberghagen, explained: "Next comes the 'wake up' for the instruments, which puts us in the position to start operating the first-ever gradiometer to be flown in space. After confirming they work, we will be ready for intensive testing of the satellite and of the scientific data-processing system on the ground."

The gradiometer is designed to produce an accurate gravity map (geoid) of Earth. This will allow a better understanding of how our planet's gravity affects dynamic processes such as sea level trends, ocean circulation and tectonic movements. ®

Bootnote

*As we understand it, GOCE is currently in free-fall orbit descending to its final operating altitude of around 260 km, at which point the scientists will doubtless require it to stop free-falling into someone's back garden. We're happy to be corrected on this point if that's not the case.

Eight steps to building an HP BladeSystem

More from The Register

next story
Malaysian Airlines flight MH17 claimed lives of HIV/AIDS cure scientists
Researchers, advocates, health workers among those on shot-down plane
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Mwa-ha-ha-ha! Eccentric billionaire Musk gets his PRIVATE SPACEPORT
In the Lone Star State, perhaps appropriately enough
MARS NEEDS OCEANS to support life - and so do exoplanets
Just being in the Goldilocks zone doesn't mean there'll be anyone to eat the porridge
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Diary note: Pluto's close-up is a year from … now!
New Horizons is less than a year from the dwarf planet
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
prev story

Whitepapers

Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.