Satellite to begin gravity quest

By Jonathan Amos
Science reporter, BBC News



Goce can fly much lower than was expected



A European spacecraft will begin its quest this week to make the most detailed global map of the Earth's gravity field.

The arrow-shaped Goce satellite can sense tiny variations in the planet's tug as it sweeps around the world at the very low altitude of just 255km.

The map will help scientists understand better how the oceans move.

It should also give them a universal reference to compare heights anywhere across the globe.
more:
http://news.bbc.co.uk/2/hi/science/nature/8268942.stm

1. The 1,100kg Goce is built from rigid materials and carries fixed solar wings. The gravity data must be clear of spacecraft 'noise'
2. Solar cells produce 1,300W and cover the Sun-facing side of Goce; the near side (as shown) radiates heat to keep it cool
3. The 5m-by-1m frame incorporates fins to stabilise the spacecraft as it flies through the residual air in the thermosphere
4. Goce's accelerometers measure accelerations that are as small as 1 part in 10,000,000,000,000 of the gravity experienced on Earth
5. The UK-built engine ejects xenon ions at velocities exceeding 40,000m/s; the engine throttles up and down to keep Goce at a steady altitude
6. S Band antenna: Data downloads to the Kiruna (Sweden) ground station. Processing, archiving is done at Esa's centre in Frascati, Italy
7. GPS antennas: Precise positioning of Goce is required, but GPS data in itself can also provide some gravity field information

...that's what spacecraft are supposed to look like.

Although ideally it should be about 5 miles long and heavilly armed.

:freak:

... who's to say that it isn't?

:hide: