For decades, space telescopes have been used to solve the mysteries of the universe. They have given scientists many exciting discoveries and greatly improved our understanding of space. Photo: Courtesy nasa.gov.in
To be launched on August 30 and named after astronomer Nancy Grace Roman, the new space telescope is expected to help scientists research phenomena like ‘dark energy’, ‘dark matter’, ‘exoplanets’ and more.
NASA has a new space observatory, designed to help scientists solve some of the biggest mysteries in astronomy, including dark matter, dark energy, exoplanets and how galaxies change and develop over time. Scheduled to be launched on August 30 from the Kennedy Space Center in Florida, using a SpaceX Falcon Heavy rocket, it has a 2.4-metre primary mirror (to identify and collect light sources), similar in size to the mirror of NASA’s existing Hubble Space Telescope. Named after Nancy Grace Roman — a scientist who played an important role in establishing NASA’s space astronomy programme, often called the “Mother of Hubble” — the Nancy Grace Roman Space Telescope will be able to capture an area of the sky about 100 times larger than what the Hubble Space Telescope can see at one time. If Hubble is like looking through a small window, Roman will be like looking at an entire neighbourhood. It is an infrared space telescope.
It is because of this increased visibility, since it can see such a large area, that astronomers will be able to create huge maps of the universe and carry out detailed studies of space. Roman will have a sensitivity towards infrared waves, similar to Hubble and is expected to provide high-quality infrared images. At the same time, it can survey and photograph the sky up to 1,000 times faster than Hubble. The new space telescope has the potential to change the way we understand the universe during the 2030s.
While NASA has launched other space telescopes since the Hubble, in its function, the Roman is closest to the Hubble, though technologically much more advanced than the older telescope.
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One of the Roman’s major goals is to answer basic questions about dark energy, a mysterious form of energy that cannot be seen directly (like gravity, it can be felt but not seen). It appears to work against gravity and is linked to the increasing speed of the expansion of the universe. Scientists estimate that dark energy makes up about 68 per cent to 72 per cent of the universe.
In 1998, scientists studying distant supernovae (the explosion of a dying star) discovered that the expansion of the universe was not slowing down. Instead, it was speeding up. This discovery led to the idea of dark energy. Roman will map hundreds of thousands of galaxies and supernovae to study how the universe is expanding and how its expansion changes over time. The telescope is expected to provide extensive data to help scientists understand this mysterious force. For example, is this acceleration caused by a new type of energy? Or is it caused by a change in our understanding of gravity on very large scales? If dark energy is a new form of energy, does its strength remain the same throughout space and time? Or has it changed during the history of the universe?
Roman will study dark energy using three important methods: Baryon Acoustic Oscillations (“vestiges of sound waves that once rippled through the primordial cosmic sea”), Distant supernovae and Weak Gravitational Lensing (“measuring how gravity subtly bends the path of light across vast distances” to reveal “ clues about the distribution of dark matter and the universe’s accelerated expansion”).
Roman will work along with the European Space Agency’s Euclid mission to study these questions.
Nancy Grace Roman, a scientist who played an important role in establishing NASA’s space astronomy programme. Photo courtesy: nasa.gov.in
Roman will also carry out a large survey of exoplanets — planets that orbit stars outside our Solar System. The aim is to find out, “How common are solar systems like ours?”, “What kinds of planets exist in the colder, outer regions of planetary systems?” and “What makes a planet suitable for life?”.
Roman will use a technique called gravitational microlensing for this. This method can find planets that are difficult to detect using other techniques, such as the radial velocity method, which measures the tiny wobble of a star caused by the gravitational pull of an orbiting planet.
It may detect planets with masses only a few times greater than that of our Moon. It may also find planets floating freely through space without orbiting a star. Some of these planets could have masses similar to Mars.
Scientists expect Roman to identify more than 1,000 exoplanets and possibly reveal tens of thousands of planetary systems. Scientists will study these planets to find out whether some of them have conditions that could support life.
The Italian mathematician and astronomer Joseph-Louis Lagrange discovered in the 18th century that there are special points where the gravitational forces of the Sun and Earth can work together in a stable way. These points are called Lagrange points after him. There are five such points: L1, L2, L3, L4 and L5. L1 is about 1.5 million kilometres from Earth toward the Sun. L2 is about 1.5 million kilometres beyond Earth, away from the Sun. NASA’s James Webb Space Telescope is operating near L2. Roman will operate near the Sun-Earth Lagrange Point 2 (L2), about 1.5 million kilometres from Earth.
From this location, it will use infrared light to study the secrets of dark energy and dark matter, which are connected with the expansion and structure of the universe. It will search for thousands of new exoplanets in our Milky Way galaxy. It will also photograph billions of galaxies and create detailed maps of the universe.
At L2, the gravitational forces of the Sun and Earth will help Roman stay in a relatively stable orbit without using large amounts of fuel. This location is much farther away than the Moon’s orbit around Earth. L2 also gives Roman a wide and continuous view of the sky. Because Earth is far away, it will not block much of Roman’s view. The telescope will also be away from much of Earth’s heat and light. This helps keep it cold. Keeping the telescope cold is very important because infrared telescopes can detect heat.
The Roman will also study dark matter, another mysterious substance in the universe. Dark matter does not produce or reflect light, so it cannot be seen directly. Scientists know that it exists because of its gravitational effects. It is estimated that dark matter makes up about 27 per cent to 30 per cent of the universe. Roman will study how dark matter is spread throughout the universe. One important method for this is gravitational lensing, when the gravity of a massive object bends the path of light coming from a more distant object. By studying these changes in light, Roman can help scientists understand the distribution and behaviour of dark matter.
Roman will also observe billions of galaxies spread across the universe. This will help astronomers understand how galaxies formed and changed after the Big Bang. By studying galaxies at different distances, scientists can look back into different periods of cosmic history. Roman will therefore help us understand how the universe has changed over billions of years.
The Nancy Grace Roman being readied for launch. Photo: nasa.gov.in
The Nancy Grace Roman Space Telescope’s instruments include the wide field instrument (WFI), which is the telescope’s main scientific camera. It has an infrared detector system with about 300 megapixels. It can observe large areas of the sky with very high accuracy and is expected to measure light from about one billion galaxies. The telescope is also armed with a coronagraph instrument, an advanced instrument designed to block bright light from stars. This allows scientists to directly study nearby exoplanets and disks of material around stars. NASA scientists hope that this technology will help future missions find and study planets similar to Earth.
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For decades, space telescopes launched by NASA and other space agencies have been used to solve the mysteries of the universe. They have given scientists many exciting discoveries and greatly improved our understanding of space.
The first to be sent to space by NASA was the Orbiting Astronomical Observatory 2 (OAO-2), launched on December 7, 1968. The OAO-2 was one of the first successful space observatories designed to study the universe from space. It was nicknamed ‘Stargazer’ and was designed to study stars and comets using ultraviolet light.
The Hubble Space Telescope was launched by NASA in 1990. Astronomer Nancy Grace Roman (May 16, 1925 – December 25, 2018), NASA’s first chief of astronomy, played an important role in developing NASA’s space astronomy programme and strongly supported the idea of using telescopes in space to study the universe. It was her continuous efforts that helped make the Hubble Space Telescope possible.
Hubble has since given us thousands of important and beautiful images and scientific discoveries about the universe. It has taken extremely clear images of the universe in visible and ultraviolet light and revolutionised astronomy and helped scientists make many important discoveries.
Next came the Chandra X-ray Observatory, launched by NASA in 1999. It is a space telescope designed to detect X-rays coming from some of the most energetic objects and events in the universe, including exploded stars and black holes.
The Spitzer Space Telescope, launched in 2003, was an infrared space telescope used to study cool objects such as distant galaxies, young stars and exoplanets. Its infrared vision also allowed scientists to observe objects hidden behind clouds of dust in space.
Six years later, NASA launched the Kepler Space Telescope in 2009, designed to find exoplanets. Kepler watched stars carefully. When a planet passed in front of a star, the star became slightly dimmer. By detecting these tiny changes in brightness, Kepler discovered thousands of exoplanets.
Then came the James Webb Space Telescope (JWST), launched on December 25, 2021. A powerful infrared telescope, Webb was designed to study some of the earliest galaxies formed in the universe and to examine the atmospheres of distant exoplanets.
Together with Hubble and other space telescopes, the James Webb Space Telescope has opened a new window into the universe. Now, the Nancy Grace Roman Space Telescope will take this journey even further by surveying huge areas of the sky and helping scientists understand dark energy, dark matter, exoplanets and the evolution of galaxies.
