Radosław Poleski, PhD, from the University of Warsaw Astronomical Observatory, has developed software that will be used to analyse the telescope’s data and search for exoplanets using gravitational microlensing.

The Nancy Grace Roman Space Telescope was launched on August 30 aboard a Falcon Heavy rocket. The mission is scheduled to last five years, although NASA reports that the telescope carries enough fuel for another five. NASA’s main international partners in the project include the European Space Agency (ESA), the Japanese space agency JAXA, the French space agency (CNES), and the German Max Planck Institute for Astronomy (MPIA).

Poleski, a professor at the University of Warsaw and researcher at the Astronomical Observatory, specialises in the search for and study of exoplanets using gravitational microlensing - a method first described by Professor Bohdan Paczyński. Polish scientists have been refining microlensing for more than 30 years through the OGLE (Optical Gravitational Lensing Experiment) project.

As the researcher said in an interview with PAP, space telescopes allow astronomers to capture images that cannot be obtained from Earth because the planet’s atmosphere interferes with observations.

“The Nancy Grace Roman Telescope is in the same class as the Hubble Telescope and similar to it in some respects, but it has a field of view 100 times larger than Hubble’s. This makes it 100 times more suitable for certain scientific tasks,” Poleski said.

For Poleski, one of the most important uses of the new telescope will be searching for exoplanets through gravitational microlensing.

“Roman will be excellent for sky surveys. It will prove effective in situations where we want to scan a large area of the sky or observe the same area repeatedly,” the scientist said.

Gravitational microlensing is a technique for studying invisible objects by observing the curvature of spacetime. The phenomenon involves the temporary brightening of light from distant stars caused by the curvature of spacetime produced by an object located along the line of sight between the star and the observer - in this case, the telescope.

“We expect to discover around 1,500 exoplanets - planets orbiting other stars - using the microlensing method; currently, we know of about 6,000. We also anticipate finding several hundred free-floating planets, objects that do not orbit any star but instead travel through the universe alone,” Poleski said.

According to the scientist, some of the planets discovered through microlensing will resemble Earth.

“They will move in Earth-like orbits around stars that are - hopefully - similar to our Sun. We are looking for a second Earth and want to determine how frequently such planets occur. That is the aim of studying the 1,500 planets we expect to discover,” he said.

Astronomers also anticipate finding approximately 100,000 additional planets using the transit method. Poleski describes the transit method as observing the transits of other objects against the background of the observed stars.

Poleski has developed the software that will be used to analyse data from the Roman telescope, specifically measurements of stellar brightness.

“If we observe a microlensing event, we will be able to determine the nature of the planet involved: whether it is more like Earth or Jupiter, which star it orbits and what its orbit is,” the astronomer said.

Poleski became involved in preparations for the Roman mission about 11 years ago.

“The first scientific proposals to build a space telescope with an aperture larger than one metre appeared 30 years ago. The Roman telescope has a 2.5-metre mirror; it was designed with microlensing - among other things - specifically in mind,” he said.

According to the researcher, the launch of the new telescope mission represents another breakthrough in astronomy, comparable to other major space observatories such as Hubble, Spitzer and the recently launched James Webb telescope.

“Webb is more versatile and has a larger mirror, but its cameras have a narrow field of view. That is why the smaller Roman telescope is optimal for other tasks,” Poleski said.

He added that Roman - with a total cost of approximately $4 billion - is also significantly less expensive than the Webb telescope ($10 billion).

Poleski personally watched the launch of the Falcon Heavy rocket carrying the telescope from the Kennedy Space Center in Florida.

“It was the first time in my life I'd seen a rocket launch, and it was an unforgettable experience. I attended the event almost as a private citizen. The telescope had already been prepared and mounted, so neither I nor my direct collaborators were involved in the launch operations in an official capacity. I was not in mission control; there was nothing for me to break or fix. However, we were given the opportunity to watch the launch from a closer vantage point than the areas open to the public. There are several such viewing spots at the Kennedy Center; I was at Banana Creek, about 6 km from the launch pad, from 6:30 a.m.,” he said.

He recalls that during the final hour before the telescope headed into space, he felt a sense of uncertainty about whether everything would go according to plan or if the launch might be delayed or postponed, a common occurrence in Florida.

“There were no surprises this time. But I was hugely surprised by the tremendous noise the Falcon Heavy's side boosters made when they landed,” he said.

The Roman telescope is scheduled to reach its destination in late November 2026. This destination is a Lagrange point located approximately 1.6 million km from Earth, where the James Webb Space Telescope and the Euclid observatory also operate. The balancing gravitational forces of Earth and the Sun allow satellites to orbit there with the same period as Earth.

“Once Roman arrives, a testing phase will begin to verify that all its components and instruments are functioning correctly and have not been shaken too severely by launch-related G-forces. The first observations should start reaching Earth early next year,” Poleski said.

The Roman telescope is designed to detect planets using the microlensing method twice a year, over 70-day periods during the transition from winter to spring and again in autumn.

“That is when it can observe the specific patch of sky near the galactic centre that interests us. So, I should have the data I am looking for by early spring, and I have high hopes for it,” he said.

The telescope is expected to collect vast amounts of data over the course of its mission.

“Importantly, all these data will be publicly available; anyone will be able to download and analyse it as part of +open science+. Of course, saving the entire dataset to a personal hard drive would be virtually impossible - we could be talking about petabytes (i.e., a million gigabytes). But once the data reach Earth and undergo initial processing, which might take about two days, they will be accessible to everyone: researchers, amateur astronomers, and even those who want to prove they can do better than scientists,” Poleski said.

Anna Bugajska (PAP)

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