An artistic rendering shows the LISA Pathfinder orbiting Earth at Lagrange Point 1, an ideal distance for observing the Earth-Sun system. The craft is held in place by the gravity of the two object's and is never in the shadow of the Earth or moon. Photo by European Space Agency/C. Carreau
PASADENA, Calif., June 7 (UPI) -- The LISA observatory mission won't launch until 2034, but it's already setting records. Recently, two test masses underwent free fall tests inside a LISA Pathfinder prototype, currently orbiting Earth at a distance of 1 million miles.
The goal of the LISA observatory mission is to observe gravitational wave signals. To do so, scientists designed a spacecraft with two test masses -- small cubes made of a gold-platinum alloy. The LISA Pathfinder, or LPF, allows the test masses to free fall and uses a series of laser instruments to measure differences in acceleration and longitudinal displacement between the two masses.
Any minuscule difference is liable to be the result of gravitational waves. The LISA Pathfinder -- and the prototype used in the latest tests -- boast a complex array of outside thrusters to ensure the craft stays out of the way of the free falling masses. The idea is to limit interfering frequencies, or noise, that might disguise gravitational wave signals.
The latest tests were surprisingly successful. The tests masses were allowed to fall with very little interference, a record for this type of instrumentation and measurement technique. For the latest tests, scientists focused on limiting noise within the frequency range of 0.7 mHz to 20 mHz.
"The noise in this range is five times lower than the LISA Pathfinder design threshold, and within a factor of 1.25 of the LISA observatory requirements," scientists announced in a press release.
"With LISA Pathfinder we have created the quietest place known to humankind. Its performance is spectacular and exceeds all our expectations by far," said Karsten Danzmann, director at the Max Planck Institute for Gravitational Physics.
"Only by reducing and eliminating all other sources of disturbance we could observe the most perfect free fall ever created," added Danzmann, who lead the development of LPF technology, "And this has shown us that we can build LISA, a space-based gravitational-wave observatory."
Researchers shared their success in a new paper, published this week in the journal Physical Review Letters.
"The results reported by the LPF team are, quite simply, a tour de force in precision measurement," researchers wrote. "These results bode extremely well for the future LISA mission."
