Roman's first big surveys
The period when the first large survey results from the Roman Space Telescope, launched on 30 August 2026, are expected to build up. Its galaxy maps will measure dark energy and its microlensing survey will find hidden planets.
The story
The Nancy Grace Roman Space Telescope was launched on a Falcon Heavy rocket on 30 August 2026. It is travelling for about 100 days to the L2 point, 1.5 million km from Earth, and is expected to arrive in early December 2026. After about 90 days of commissioning, NASA expects to release the first science images in early 2027. By around 2030, the first large survey results are expected to be building up.
Roman's key feature is its wide view. It sees about as sharply as Hubble, but each picture covers an area of sky more than 100 times larger than Hubble's cameras. Because of this, NASA expects Roman to collect light from about a billion galaxies over its mission.
The first goal is dark energy. The universe is expanding faster and faster, and scientists call the unknown cause 'dark energy', but they do not yet know what it is. Roman will measure how a huge number of galaxies are spread out, and how slightly their shapes are bent by gravity, to look for clues to this puzzle.
The second goal is exoplanets. Roman will watch hundreds of millions of stars towards the centre of the galaxy again and again for months. When a star or planet passes in front of a more distant star, its gravity acts like a magnifying glass and briefly makes the background star brighter. This is called microlensing, and it is expected to find more than a thousand planets far from their stars, as well as planets drifting without any star.
Mission goals
Hubble and the James Webb Space Telescope look very deeply at small patches of sky. Roman photographs large pieces of the sky at once with similar sharpness. Very rare objects, such as extremely distant galaxies or unusually bright supernovae, can only be caught by covering a wide area, and the more of them are collected, the more precise the measurements of the universe become.
Dark energy appears to make up about 70% of all the energy in the universe, but its nature is unknown. What scientists most want to know is whether dark energy always stays the same or changes over time. Combining Roman's data with data from ESA's Euclid telescope, launched in 2023, is expected to bring them closer to an answer.
Microlensing finds planets that other methods tend to miss. Watching a star dim as a planet passes in front of it works best for planets close to their stars, and watching a star wobble works best for heavy planets. Microlensing can also catch light planets far from their stars, which helps show whether arrangements like our own Solar System are common or rare.
Mission chronology and background
Roman's main mirror is 2.4 m across, the same size as Hubble's. The mirror was handed to NASA in 2012 by the US National Reconnaissance Office (NRO). It had been built for another purpose and was given a new life as a space telescope. The telescope is named after Nancy Grace Roman, NASA's first chief of astronomy, who is also called the 'mother of Hubble'.
The main mission lasts five years, but the telescope carries enough fuel for at least 22 years. Most of the observing time goes to large surveys, such as mapping galaxies, watching supernovae and the microlensing survey of the galactic centre. NASA expects the galactic centre survey alone to also find about 100,000 planets passing in front of their stars.
Roman's data will be released right away, with no period in which one team has it first. Because of this, the first results are more likely to come from researchers around the world analysing the same data together than from a single team's announcement. The telescope also carries a coronagraph, which blocks starlight to photograph planets directly. It is a technology test that aims to reduce starlight to about one part in a billion.
Other milestones of this mission
Where to see it — sky and simulator
Like the James Webb Space Telescope, Roman will orbit around the Sun–Earth L2 point. At 1.5 million km from Earth, about four times the distance to the Moon, it cannot be seen with the naked eye or an ordinary telescope. Zooming in around Earth in the orbit view shows a marker for Roman next to Webb at L2.
The microlensing survey looks towards Sagittarius, in the direction of the centre of our galaxy. Choosing the galactic centre in the sky view shows whether that direction is above the horizon from the current location. In the interstellar view (3D), the distance of about 26,000 light-years from the Sun to the galactic centre is shown to true scale.
The wide surveys that map galaxies mostly point away from the Milky Way. In those directions there are fewer stars and less dust from our own galaxy, so distant galaxies are easier to see. Zooming into areas far from the band of the Milky Way in the sky view shows this kind of 'clean' sky.
FAQ
Has Roman launched?
Yes. It launched on a Falcon Heavy on 30 August 2026 and is expected to reach L2 in early December 2026. The first science images are expected in early 2027.
When will the first big results come?
Data must build up after the surveys begin, so major results are expected from around 2030.
How is it different from Hubble and Webb?
Its sharpness is similar to Hubble's, but each image covers more than 100 times the area. It is built for width rather than depth.
How many exoplanets might it find?
More than a thousand planets far from their stars through microlensing, and about 100,000 planets passing in front of their stars.
Can anyone use the data?
Yes. It is released right away, without an exclusive period.
Related
- Roman Space Telescope launch
- James Webb Space Telescope launch
- Hubble Space Telescope launch
- James Webb — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.