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Hacking Cassini To Detect Gravity Waves
lennon writes: "With some upgrades to the tracking equipment, NASA is going to try to detect gravitational waves by tracking the speed of the Cassini probe. They've tried this with other spacecraft, but the sensors have evolved since then. Complete press release is here. Looks like a neat hack."
What I find truly interesting about all this is not just that they are measuring the velocity changes (the acceleration) of the Cassini probe, but that after getting back the information of the forces at work, they will have to somehow determine exactly where the gravitational waves are coming from.
Think of it this way: If two planets are on opposite sides of the probe, and both are emitting gravitational forces, then the probe will be subjected to the net forces of the two planets. The equation for relative force of gravity comes to mind here, and I assume they will be using it when calculating multiple sources of gravity.
(GmM)/(R^2) gives the acceleration of the system for two masses in space, so any resultant force must take into account that it could come from several different masses.
JPL engineers have carefully instrumented a large dish antenna at the Deep Space Network's Goldstone complex near Barstow, Calif., to send and receive the higher frequencies with unprecedented Doppler sensitivity. The upgrade includes refined pointing capability needed to exploit the higher frequencies, said Sami Asmar, supervisor of JPL's Radio Science Group. Other new equipment at Goldstone will allow researchers to correct for the atmosphere's distortion of radio transmissions and improve performance of the search.
As I see it, the trickiest thing here will be taking the "exquisitely accurate measurements" and turning them into real, useable models of gravity given off by our neighboring planets.