The European Space Agency (ESA) has announced that both LISA, the space gravitational wave observatory, and PLATO, a new planet-hunter mission, will move ahead.

LISA (Laser Interferometer Space Antenna) has officially been selected by ESA as the third large-class (L-class) mission and now scientists can get into the detailed design and cost of the project. Once those are ironed out it will be proposed for adoption, and if everything goes smoothly it will launch in 2034.

That date seems very far in the future but time is necessary to construct this observatory as nothing like it has ever been attempted before. Three craft will fly in perfect formation 2.5 million kilometers (1.5 million miles) from each other, connected only by laser beams. Gravitational waves will affect those laser beams and, thanks to the precise alignment, the craft will detect the changes.

To demonstrate that this is actually possible, LISA has a test mission, called LISA Pathfinder, which was launched last year and will stop operation this month. LISA Pathfinder has demonstrated it is five times more precise than was expected.

LISA will join the two other L-class missions, JUICE, (JUpiter ICy moons Explorer), which is expected to launch in 2022, and ATHENA (Advanced Telescope for High-ENergy Astrophysics), expected to launch in 2028 and will detect X-rays from the most energetic events in the universe.

In the same meeting that LISA's future was decided, a new planet-hunter telescope was also approved. PLATO (PLAnetary Transits and Oscillations of stars) will look for new exoplanets by carefully studying the small wobbles that the gravitational pull of planets generates on their host star.

“We are very pleased that PLATO has reached adoption and that the mission is now moving forward into its next decisive phase,” Prof. Dr. Laurent Gizon, director of the MPS and head of the PLATO Data Center, said in a statement.

“Using observations of stellar vibrations, PLATO will for the first time fully characterize these stars and their planets with regard to mass, radius, and age. This will revolutionize the study of the evolution of exoplanets and their host stars.”

PLATO will consist of 26 telescopes mounted on a single spacecraft that will give the probe a large field of view, so it could monitor a wide chunk of the sky. It will monitor each patch of the sky for up to two years so that it could observe two potential passes by an Earth-twin.  

The mission will last for at least four years and it is slated to launch in 2026.