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Nancy Grace Roman Space Telescope Launch Advances Study of Dark Matter, Dark Energy, and Exoplanets
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Olhar Digital
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Nancy Grace Roman Space Telescope Launch Advances Study of Dark Matter, Dark Energy, and Exoplanets

With the successful launch of the Nancy Grace Roman Space Telescope, transported by a SpaceX Falcon Heavy rocket last Sunday (30th) from the Kennedy Space Center in Florida, NASA has initiated a new and unprecedented phase in the investigation of the Universe.

The deployment of this observatory to Lagrange Point 2 (L2), located over 1.6 million kilometers from Earth, marks the beginning of a mission focused on solving three major current scientific questions: the hidden composition of the cosmos, the dynamics of spatial expansion, and the search for new worlds in the Milky Way.

Over the last century, science has established that everything directly visible to humanity—from stars and planets to entire galaxies—constitutes only 5% of the Universe. The majority of physical reality is composed of substances that do not interact by emitting, reflecting, or absorbing light. Understanding this invisible structure is the central purpose guiding the technological design of the Roman telescope.

Dark matter remains one of the biggest enigmas in astrophysics. Its existence is proven by the gravitational effect it exerts on galaxy rotation, acting as a network that prevents celestial bodies from dispersing; however, no terrestrial equipment has managed to register its constituent particles.

The Roman telescope proposes a distinct methodology. Instead of trying to capture dark matter in a laboratory, it will use its vast field of view to map the distortions caused by the gravity of this invisible substance on the light from billions of distant galaxies. This phenomenon, known as gravitational lensing, will enable the creation of a high-precision three-dimensional map, illustrating the distribution of matter across billions of years of cosmic history.

In parallel, the observatory will investigate the mystery of dark energy. This unknown force, identified in the late 1990s, operates opposite to gravity, driving the accelerated expansion of spacetime itself. To measure the behavior of dark energy throughout the ages, Roman will record the location of numerous galaxies and analyze Baryon Acoustic Oscillations—marks left by pressure waves in the early cosmos that function as a standard ruler for calculating the rate of universal expansion.

The results of these observations may validate existing cosmological models or compel physicists to develop new theories about gravity and spacetime.

Scientific Perspectives and Planetary Advances

During the live broadcast of the launch, conducted by Olhar Digital, astronomer Marcelo Zurita stated that the solution to this cosmic mystery lies among the highest honors of global science. He declared that 'whoever manages to explain very assertively the origin and nature of dark energy will certainly need to be awarded the Nobel Prize.'

In addition to investigating the cosmic scale, the mission represents a significant leap in planetary scale. The search for exoplanets (planets outside the Solar System) will enter a new instrumental phase thanks to the advanced coronagraph onboard the observatory, an optical system designed to overcome intense stellar brightness and reveal planets in their orbits.

In an interview with the Olhar Espacial program, astrobiologist Raíssa Estrela, a researcher at NASA's Jet Propulsion Laboratory (JPL), detailed the functioning and urgent importance of this technology for space research. She explained that 'this technology we call a coronagraph is basically an instrument that blocks the light of the parent star. And why do we want to block this light? Because when we block the light of the parent star, we can see the light reflected by the planets inhabiting that star. The star's brightness is so strong that it overwhelms the entire image. So, we need to block it to see the light reflected by the orbiting planets. With this type of observatory, we will be able to image the planetary system.'

Currently, most exoplanets are discovered through indirect methods, such as the momentary dimming of starlight when a planet transits in front of it. With Roman's coronagraph, astronomers will have the ability to record the light directly reflected by the planet, starting the focus on giant gaseous worlds similar to Jupiter.

To map smaller and more distant bodies, the observatory will employ the combined technique of gravitational microlensing. When a star is positioned in front of another more distant one relative to Earth, the gravity of the foreground star acts as a natural lens, intensifying the brightness of the background star. If the lensing star possesses planets, the gravity of these worlds generates small variations in the light signal. This strategy will allow scientists to catalog thousands of new planets, including rocky worlds located tens of thousands of light-years from our system.

According to Zurita, gravitational microlensing is the most appropriate method for identifying Earth-sized planets. 'If the main goal is to find a 'Earth 2.0' (an Earth-like planet in the habitable zone), this is the technique to be used.'

The dataset collected by the Roman telescope will serve as a strategic basis for future space missions. The ultimate goal of astrobiology—detecting biological signs in the atmosphere of a planet with mass and temperature similar to Earth—demands a level of technical accuracy that is currently being established.

Raíssa emphasized the pioneering role of the new telescope in NASA's exploration planning. 'Roman will study other planets, but it will be more focused on gas giants. The technology will not reach the point of characterizing planets like Earth. But it will bring this technology that we need to understand, which is direct imaging of exoplanets, which will be used by the Habitable Worlds Observatory, but for smaller planets. So, it is like the first step we are taking in this journey toward characterizing Earth-like planets.'

All this research will be supported by an unprecedented capacity for information processing. Equipped with the Wide Field Instrument (WFI), a 300-megapixel camera that captures areas a hundred times larger than those of the Hubble Space Telescope, Roman can generate over 20 petabytes of data in its first five years.

This colossal volume will require intensive use of artificial intelligence and machine learning algorithms to analyze images and catalog billions of astronomical objects. By integrating cutting-edge technology, theoretical physics, and space engineering, the launch does not just signify the start of another NASA mission, but the most crucial step taken to date to decipher the hidden nature of the Universe and our place within it.

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DESI results spark debate on the nature of dark energy: possible change in its properties
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olhardigital.com.br

DESI results spark debate on the nature of dark energy: possible change in its properties

For decades, the standard cosmological model treated dark energy as a constant value responsible for the accelerating expansion of the Universe. However, results published in 2025 using the Dark Energy Spectroscopic Instrument (DESI) have revealed an intriguing possibility: this mysterious component may not be constant and could change over time.

The second series of DESI data (DR2), based on observations from the first three years, showed consistency with the standard cosmological model ($ ext{\Lambda CDM}$), which assumes the constancy of dark energy. At the same time, these results pointed towards a preference for the hypothesis of its evolution throughout the history of the Universe.

In a study published on March 19 last year, the DESI collaboration combined DR2 data with observations of the cosmic microwave background and three sets of Type Ia supernovae. Depending on the sample used, the analysis showed a preference in the range of 2.8 to 4.2 sigma for a model that allows for the evolution of dark energy.

It is important to note that this result does not mean that DESI has discovered a new form of energy, as the statistical significance is still below the 5-sigma threshold typically associated with a scientific discovery. Furthermore, the analysis itself depends on the combination of different datasets and the mathematical description of dark energy's behavior.

It is in this area that subsequent works have begun to re-evaluate the interpretation of the obtained data. One of the latest doubts arose on July 31 from a study conducted by Jin-Young Kim from Stanford University and the investment firm Two Sigma, as well as David F. Mota and Andrius Tamosiusnas from the University of Oslo, Norway.

The team applied a statistical approach developed for re-analyzing the same data as it becomes available. Bruno Quint, an astrophysics doctor from the University of São Paulo (USP) and operations specialist at the Vera C. Rubin Observatory, noted that such re-evaluations highlight fundamental questions about the very nature of dark energy. He stated in an interview with Olhar Digital: 'The honest answer begins with acknowledging: we do not know what it is. Dark energy is a name we gave to what causes the Universe's expansion to accelerate, without defining its nature.'

This uncertainty helps explain why different analyses may reach different conclusions when trying to determine whether dark energy is truly constant. In a new study, scientists noticed that the evidence is concentrated almost exclusively in the LRG2 range, which corresponds to a specific distance and epoch in the history of the Universe determined by redshift.

When this range is excluded from the analysis, the result shifts slightly towards the $ ext{\Lambda CDM}$ model. Moreover, when considering the possibility of an excess in any of the seven analyzed regions, the signal fails to maintain statistical correction.

Based on these results, the authors classify this signal as fragile, concentrated in one region, and dependent on the test specification, rather than considering it reliable evidence for dynamic dark energy.

A few days earlier, on July 26, another group reached a similar conclusion using a different method. The study employed a statistical technique known as Gaussian process, which allows reconstructing the history of the Universe's expansion based on data without requiring a prior assumption about the specific formula for dark energy's behavior.

The combination of DESI DR2 data with information on the cosmic microwave background, supernovae, and 'cosmic chronometers' still showed some preference for evolving dark energy. However, this preference weakened when researchers tested various models and data combinations. In some analyses, the difference from the standard model was close to 1 sigma, which is considered a weak level for substantiating scientific proof.

Another re-evaluation led to an even more provocative conclusion. In a paper by Dilin Duan Ing, David Yallup, and Will Hendley, all from the University of Cambridge, UK, they analyzed the results using a Bayesian approach that penalizes more complex models. When using DESI data and the Planck satellite, the indication of possible dark energy change lost strength. When the researchers used a revised version of the supernova data, this evidence disappeared. According to the authors, part of the previous signal might have been caused by the way this data was calibrated.

Despite this, not all recent studies weaken this hypothesis. An analysis published on July 1 showed that the preference for dynamic dark energy persists when considering various extensions of the cosmological model. In the most optimistic estimates, DESI's preference for the dynamic model reached 99.995% confidence—about one in twenty thousand chance of randomness. Nevertheless, as Quint explains, astronomy requires even greater rigor. 'This is below near-complete certainty that astronomers usually require to announce a discovery.'

Another work, available for review on the arXiv repository on August 7, presented a possible additional explanation for part of the discrepancy. Nils Schöneberg from Ludwig Maximilian University of Munich and Max Planck Institute for Physics; Rodrigo Calderon from Ludwig Maximilian University of Munich; and Julien Lesgourgues from Technical University of Munich and Max Planck Institute for Physics, all from Germany, argue that solutions to the Hubble tension problem related to early Universe physics could significantly reduce the evidence attributed to dynamic dark energy.

Thus, the situation is far from a final conclusion. DESI data continues to show an interesting anomalous effect compared to the simplest model of the Universe, but independent studies indicate that the strength of this evidence depends on how the data are combined, calibrated, and analyzed.

At present, the most important question is not whether dark energy has 'disappeared' or is 'weakening.' It is crucial to find out whether the observed signal represents a real characteristic of cosmic expansion or a combination of statistical, systematic effects, and model selection. New data will be decisive in clarifying this issue. Observatories such as Euclid, Nancy Grace Roman, and Vera C. Rubin will be able to provide new observations of the Universe's expansion and help verify whether different datasets point to the same conclusion. 'Testing this possibility—comparing different effects and observing their consistency—is precisely what the Rubin Observatory was built for,' concludes Quint.

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