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Lisa Pathfinder, an experimental probe to test the technologies for measuring gravity waves in space, was successfully launched today by Arianespace’s Vega rocket.
At its core is a pair of free-floating, identical 46 mm gold–platinum cubes separated by 38 cm, which will be isolated from all external and internal forces acting on them except one: gravity. “LISA Pathfinder will put these test masses in the best free-fall ever produced in space and monitor their relative positions to unprecedented precision,” says Karsten Danzmann, who also is the Co-Principal Investigator for the LISA Pathfinder Technology Package, the scientific heart of the satellite. “This will lay the foundations for future gravitational-wave observatories in space such as eLISA.”
It is important to point out that this probe will not measure gravity waves. It doesn’t have the sensitivity to do it. Instead it is testing the engineering, as described above, for building a later probe that will have sensitivity. To gain that sensitivity the floating cubes must be much farther apart, and likely will require several independent satellites flying in formation.