The European Space Agency’s (ESA) space observatory for gravitational waves is about to get a substantial sight upgrade thanks to Dutch innovators. The first-of-its-kind observatory, known as the Laser Interferometer Space Antenna (Lisa), is set to launch in 2034, but not before receiving some major hardware upgrades from a consortium of Dutch research institutions, including TNO, SRON (space research) and Nikhef (subatomic physics).
Gravitational waves can be used to detect events in the universe that are invisible to our telescopes, like collisions between stellar black holes or neutron stars. Observatories on earth, however, are unable to sense gravitational waves over 10,000 kilometers long. As a result, ESA is developing Lisa, which will use its 2.5 million-kilometer ‘arms’ to detect much longer wavelengths. These arms are formed by three satellites, which are constantly moving relative to each other within a margin of about ten thousand kilometers and which utilize laser beams to align themselves to one another and to measure the distance between them.
For this feat, TNO is charged with developing a mechanism that can aim the lasers, with the precision of milliarcseconds under extreme space conditions, for the alignment of the optical systems. Meanwhile, SRON and Nikhef have contracted Dutch companies, Bright Photonics and Smart Photonics, for the development of a prototype of a new laser detection system. This system, known as quadrant photodiodes, registers the infrared laser beams between Lisa’s three satellites. The lasers have a power of 1 watt but diverge over the vast distance, resulting in only about 500 picowatts remaining upon arrival. To increase detection sensitivity, Bright Photonics and Smart Photonics use indium gallium arsenide.
“The combination of short and long wavelengths means that after the recent spectacular start of the new field, we’ll get a much more complete picture of the universe, in gravitational waves, in the future,” says Radboud University professor Gijs Nelemans, the initiator of the Dutch Lisa collaboration. Prototypes of these new contributions are expected to be ready for a first aptitude test within about a year.