NASA’s Roman telescope: How James Webb’s successor will map the universe with colossal amounts of data

The James Webb Space Telescope continues to unravel the beauty and mystery of the cosmos since it delivered its first images last July — but the mission to install the next big space telescope is already well underway.

The Nancy Grace Roman Space Telescope will be the next major space telescope to launch after the deployment of the latest NASA telescope, which itself was the successor to the still-active Hubble Telescope.

Roman’s launch will usher in “a new age of astronomy,” one of the European Space Agency (ESA) scientists working on the project told Euronews Next; it will collect more data than any other NASA mission launched before and attempt to answer some of the biggest questions in astrophysics.

Scheduled for launch no later than 2027, it will be able to capture “a more panoramic view of the universe and allow more statistical studies,” explained Marco Sirianni, ESA’s Science Operations Development Manager, who is working on the project with NASA.

While a NASA-led mission, ESA is contributing some of the technology and expertise to the mission, in exchange for access to the unprecedented amount of data it will provide.

Here’s a look at what to expect from the next big NASA space telescope.

How will Roman differ from Hubble and James Webb?

While Hubble and Webb are extremely good at zooming in to get a detailed look at small parts of the sky, Roman will have a much wider field of view.

It will be able to create infrared images 200 times larger than Hubble, while providing the same rich level of detail of its equivalent size 2.4 meters in diameter.

So while it will be able to produce the “exquisite” images we’ve grown accustomed to from Hubble and Webb, it will primarily “be a telescope dedicated to surveys,” Sirianni said.

“To look for the stellar population of a nearby galaxy, which is too large for Hubble’s field of view, we have to stitch and make mosaics of very different shots. With Roman, we can take a picture of the entire galaxy in a single shot,” says he.

For example, a recent “mosaic” of our neighboring galaxy Andromeda was put together with 400 individual images taken by Hubble. Roman will be able to paint the same large picture with the same level of detail with only two images. And these much larger images mean an unprecedented amount of data will be collected.

“Just to give you an idea, in 30 years of Hubble operation we’ve collected something like 170 terabytes of data,” Sirianni explained. “For Webb, we expect in five years to have 1,000 terabytes. And for the 5-year nominal life of Roman, we expect to have 20,000 terabytes”.

Ultimately, it will collect data on billions of galaxies to create a “3D model of the universe”.

Answering Cosmic Mysteries

With this panoramic view of the universe, NASA and its partners hope to answer some of the biggest questions facing astrophysics.

One of the goals is to test Albert Einstein’s general theory of relativity, which is well tested in relation to e.g. the scale of our solar system, but less so on larger cosmological scales.

Visible matter in the universe should, according to the theory, slow down the expansion of the universe, so scientists attribute the universe’s expansion rate to a mysterious component – dark energy – which they believe makes up about 68 percent of the universe.

Roman will provide us with data that can accurately measure the position and distance of millions of galaxies and will help us understand the rate of expansion of the universe in different areas.

Ultimately, the results will tell us whether Einstein’s theory of gravity needs to be modified.

Exoplanet census

Another of Roman’s top goals is to spot thousands of new exoplanets in our galaxy using a technique called gravitational microlensing.

“If two stars are aligned, the one in front will distort and magnify the light from the star behind. And if the star in the foreground has a planet, we will see the effect of the planet on the light from the star behind it,” Sirianni said.

Given Roman will count billions of stars, it will give a “very good count of how many stars will have exoplanets,” he added.

Not only will it discover new exoplanets, but Roman will carry another main instrument – called a coronagraph – which aims to image exoplanets that are close to their parent star. “This is a very difficult technique because the starlight has to be suppressed — it’s orders of magnitude brighter than the objects you want to study, the nearby planet,” Sirianni said.

Coronagraph on Roman will attempt to directly capture large Jupiter-like planets by performing direct corrections to improve image quality.

It will be a demonstration instrument – and if it proves to work, it will form the baseline for the technology to be used on future space observatories that will try to directly image Earth-like planets in their parent star’s habitable zone.

ESA’s contribution to Roman

ESA is contributing three key pieces of technology to the Roman mission, in exchange for access to the data and a seat at the table during the mission.

The space agency will provide “star trackers,” small telescopes in the spacecraft that constantly determine its position in the sky by tracking stars. Then it will deliver batteries to help power the spacecraft before its solar panels are deployed.

And finally, it will also supply detectors for the onboard coronagraph.

Furthermore, ESA’s own mission to measure the expansion of the universe and reveal more about dark energy will be launched this summer.

The Euclid Space Telescope will collect the information that will then be complementary to the data collected by Roman.

Like ESA’s contribution to Roman, NASA is also making small contributions to the Euclid mission.

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