NASA's Roman Mission: Will Nancy Grace Roman Telescope Find 100,000 Exoplanets?

Thousands of exoplanets, or planets beyond our solar system, have been detected by telescopes in the last decade, offering us a tantalizing insight into future worlds beyond our own. However, future telescopes will be able to explore much more, such as the NASA Nancy Grace Roman Space Telescope, which is expected to find tens of thousands of exoplanets.

(Photo: NASA)
The Nancy Grace Roman Space Telescope, formerly known as WFIRST, will function as Hubble’s wide-eyed cousin. While just as sensitive as Hubble's cameras, the Roman Space Telescope's 300-megapixel Wide Field Instrument will image a sky area 100 times larger. This means a single Roman Space Telescope image will hold the equivalent detail of 100 pictures from Hubble.

How Roman Space Telescope Would Detect New Exoplanets

Roman will use a technique known as microlensing to identify new planet candidates. This is accomplished by gazing at a large number of stars and seeing as one star crosses in front of another from Earth's perspective. As this occurs, the foreground star's gravity bends the light emitted by the background star, resulting in a slight brightness fluctuation. This enables scientists to learn more about the foreground star, such as if it is home to planets.

The difficulty with this approach is that two stars aligning perfectly are extremely rare. The telescope must track millions of stars to maximize the likelihood of seeing one cross in front of the other to find two stars lined up.

"Microlensing events are rare and occur quickly, so you need to look at a lot of stars repeatedly and precisely measure brightness changes to detect them," astrophysicist Benjamin Montet, a Scientia Lecturer at the University of New South Wales in Sydney, said in a statement.

This is useful in a variety of ways, as such observations allow for the identification of a particular form of exoplanet using the transit method. "Those are the same things you need to do to find transiting planets," Montet explained, "so Roman will create a good transit survey as well by building a robust microlensing survey."

When a planet moves between a star and us, the transit method searches for dips in the brightness of the star. This adds another tool for finding many more exoplanets using the same results. This approach works best for planets that are close to their stars, while microlensing works best for planets that are far away from their stars.

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"The fact that we'll be able to detect thousands of transiting planets just by looking at microlensing data that's already been taken is exciting," said study co-author Jennifer Yee, an astrophysicist at the Center for Astrophysics, Harvard & Smithsonian in Cambridge, Massachusetts. "It's free science."

According to a Montet research paper, Roman could detect up to 100,000 planets using microlensing, and it could find even more using the transit process. The telescope will be operational in the mid-2020s.

Explosion for Exoplanets

Experts observed the first exoplanets in 1992, Digital Trends said. The same report mentioned that the number of observed planets outside of our solar system has exploded in less than three decades. NASA said that the number of observed exoplanets doubles every 27 months.

Ground-based telescopes were first used to discover exoplanets, such as the famous discovery of exoplanet 51 Peg b in 1995, for which two Swiss astronomers were awarded the Nobel Prize. But it wasn't until the advent of space-based planet-hunting telescopes like NASA's Kepler and TESS missions that exoplanet-hunting really took off.

New NASA and ESA (European Space Agency) missions are now discovering and studying distant exoplanets in greater detail than ever before.