New telescope unveiled: "it’s like adding sounds to motion pictures”

Scientists are arming themselves for the LISA space mission to track down and measure time-bending gravitational waves.

The European Space Agency (ESA) and NASA are working to create a Laser Interferometer Space Antenna (LISA) to catch and measure gravitational waves in space.

LISA will be a constellation of three spacecraft that orbit the Sun, creating a massive triangular field larger than our star. This field will serve as a giant detector and alert scientists if a gravitational wave appears. The three spacecraft send laser beams to each other, which are combined to detect gravitational waves.

The LISA mission is planned to be launched in the 2030s.

Gravitational waves explained

Space-time could be imagined as a fabric or trampoline, where high-mass celestial bodies bend the fabric with their weight, and this curvature pulls other objects towards them.

Gravitational waves are distortions in spacetime, which appear and ripple across the universe when two massive black holes, a billion times bigger than the Sun, collide or merge. The movement coming out of supermassive black holes creates a huge gravitational ripple that has the power to stretch and compress the objects in its way.

Albert Einstein mathematically predicted the existence of such a phenomenon in 1916, drafting his general theory of relativity. The existence of gravitational waves was first demonstrated in the 1970s and 80s and first detected in 2015 using the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Some gravitational waves are enormous. For example, waves at low frequencies can have wavelengths larger than the Earth itself, so we need to go to space to measure them.

Engineers working on telescope designs

As part of preparation for the mission, on October 22nd, NASA first revealed a full-scale prototype for six telescopes that will be used aboard the LISA’s mission.

“Twin telescopes aboard each spacecraft will both transmit and receive infrared laser beams to track their companions,” said Ryan DeRosa, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“The prototype called the Engineering Development Unit Telescope, will guide us as we work toward building the flight hardware.”

Telescopes work best close to room temperature. That’s why the engineers coated the primary telescope’s mirror in gold to reflect infrared lasers and reduce heat loss in the harsh space environment.

Also, the telescopes need to be made from materials that do not deform in a wide range of temperatures, and that’s why a glass ceramic called Zerodur was chosen. This material is widely used for telescope mirrors.

Why should we care about gravitational waves?

According to ESA, the discoveries of LISA’s mission will help astrophysicists trace the origin and behavior of black holes, which is a core riddle in the evolution of galaxies.

As gravitational waves can show the distance to the objects that emit them, studying them will assist scientists in measuring changes in the Universe's expansion.

Also, capturing the ripples from the Universe's first moments could unveil what happened in the seconds after the Big Bang.

“For centuries, we have been studying our cosmos through capturing light. Coupling this with the detection of gravitational waves is bringing a totally new dimension to our perception of the Universe,” says scientist Oliver Jennrich, who is working on the LISA project.

“If we imagine that, so far, with our astrophysics missions, we have been watching the cosmos like a silent movie, capturing the ripples of spacetime with LISA will be a real game-changer, like when sound was added to motion pictures.”