U.S. scientists say they're one step closer to "hearing" gravity waves, the ripples in space and time predicted by Albert Einstein in the early 20th century.

Engineers at NASA's Jet Propulsion Laboratory have tested a system of lasers intended for a space mission called the Laser Interferometer Space Antenna, or LISA, NASA said in a release Tuesday.

The goal of the mission is to detect the subtle, whisper-like signals of gravitational waves, which have yet to be directly observed.

The JPL test has reached a significant milestone, demonstrating that noise, or random fluctuations, in the system's laser beams can be hushed enough to allow the detection of the subtle and elusive waves.

"In order to detect gravitational waves, we have to make extremely precise measurements," Bill Klipstein, a physicist at JPL, says.

"Our lasers are much noisier than what we want to measure, so we have to remove that noise carefully to get a clear signal; it's a little like listening for a feather to drop in the middle of a heavy rainstorm."

LISA is a joint European Space Agency and NASA mission proposal, which, if selected, would launch in 2020 or later.

LISA was given a high recommendation by the 2010 U.S. National Research Council decadal report on astronomy and astrophysics in August.