Nasa to launch $4.3bn space telescope to scan universe
Roman Space Telescope is expected to help explain dark matter while discovering thousands of planets beyond our solar system
Nasa is launching a new observatory designed to scan vast swaths of sky, potentially discovering tens of thousands of distant planets and shedding light on the mysteries of dark matter and dark energy.
The Roman Space Telescope, named after the late Nancy Grace Roman, Nasa’s first chief astronomer and a leading architect of the agency’s space observation programme, is scheduled to launch on Sunday. The $4.3bn mission will complement the Hubble and James Webb space telescopes, launched in 1990 and 2021.
Roman stands out from other space observatories for its very wide field of view which will enable it to scan large areas of sky in infrared light. “Where Webb goes deep, Roman will go big,” said Julie McEnery, Roman project scientist with Nasa.
At any moment Roman will see 200 times more of the sky than Hubble and it can move far faster between images. “A survey that would take Roman one month would take a century with Hubble,” McEnery said. “Roman doesn’t just do Hubble science faster. It can address entirely new, ambitious science questions.”
One of the mission’s main purposes will be to assess the effects of dark energy and dark matter on the shape and distribution of billions of stars and galaxies. The nature of both is unknown. Cosmologists believe dark energy — a force driving space apart — makes up about 68 per cent of the universe, while invisible dark matter accounts for 27 per cent and all the ordinary matter that telescopes can image directly is just 5 per cent.
Another task for Roman will be to search for planets beyond our solar system known as exoplanets. Nasa expects the telescope to discover as many as 100,000 exoplanets to add to the 6,300 currently known, using several different techniques.
Beth Biller, an astronomy professor at University of Edinburgh, will be working on observations with Roman’s coronagraph, an instrument that blocks the glare from a star and makes it possible to image its individual planets and their atmospheres directly from the reflected starlight.
“I’m excited that in the next year we may have our first reflected-light images of exoplanets — and I think that’s how we will eventually find planets like our own Earth,” she said.
The coronagraph will be developed further for the Habitable Worlds Observatory, Nasa’s next flagship telescope mission, which is expected to launch in the 2040s to look for life on Earth-like planets.
Roman is scheduled to launch on Sunday at 7.26am local time from Kennedy Space Center in Florida on a Falcon Heavy rocket made by Elon Musk’s SpaceX.
Its destination 1.5mn km away is the “second Lagrange point” L2, where it orbits the Sun at exactly the same speed as Earth and can always point out into deep space without being blinded by solar or terrestrial light. The James Webb Space Telescope is also located there, in contrast to Hubble, which orbits just 540km above Earth.
“L2 is a very dark part of the solar system,” Biller said. “You’re always pointing away from the Sun and the temperature is stable, so it is an excellent observing point.”
The project has an unusual history, starting with the transfer to Nasa of a surplus telescope by the US National Reconnaissance Office, which makes spy satellites. The space agency was able to repurpose it for the Roman mission, to look out into the sky rather than down at the Earth.
Unlike most big science projects, Roman has come in within its planned $4.3bn budget and ahead of schedule. The original target launch date was May 2027.
Scientists around the world are waiting eagerly for Roman’s observations to emerge over the next few years. “I suspect its greatest legacy may come from the way it surveys the sky,” said Noelia Noël, an astrophysicist at the University of Surrey in the UK.
“When you observe an enormous area of the sky repeatedly with this level of depth and resolution, you create conditions for discovering phenomena that no one designed the telescope to find,” she added. “What excites me most is the prospect of unexpected discoveries coming from questions we haven’t thought of asking yet.”