Nancy Grace Roman Space Telescope

Nancy Grace Roman Space Telescope

Source: Indian Express
GS III: Science and technology-  Developments and their applications in everyday life, Awareness in the fields of space technology and scientific developments

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Why in the News?

NASA launched the Nancy Grace Roman Space Telescope, a powerful next-generation space telescope, on August 30 aboard a SpaceX rocket.

News in Brief

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• The Nancy Grace Roman Space Telescope is a next-generation space observatory with capabilities between the Hubble Space Telescope and the James Webb Space Telescope (JWST) in terms of the scale and nature of its scientific observations.
• It is designed to investigate some of the universe’s deepest mysteries, particularly exoplanets, dark matter and dark energy.
• The telescope is named after Nancy Grace Roman, a pioneering NASA astronomer who played a key role in the development of the Hubble Space Telescope.

Scientific Objectives

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• The Nancy Grace Roman Space Telescope will help scientists study some of the major unanswered questions in astronomy.
• Its key objectives include,
  • Detecting and studying exoplanets beyond our Solar System.
  • Investigating the nature and distribution of dark matter.
  • Improving our understanding of dark energy and the expansion of the universe.
  • Studying gravitational lensing, where gravity bends the path of light.
  • Mapping the distribution and structure of galaxies and galaxy clusters.
  • Understanding the evolution and expansion of the universe.
• The telescope will also help create a three-dimensional map of galaxies and galaxy clusters, providing a better picture of how matter is distributed across the universe.

Exoplanent Studies

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• Exoplanets are planets that exist outside our Solar system.
  • Most known exoplanets orbit stars other than the Sun.
• They generally orbit other stars, including ordinary stars as well as remnant stars, which are the remains of stars that have exhausted their fuel.
• More than 6,000 exoplanets have been identified so far, but this is considered only a small fraction of the planets that may exist in the Milky Way.
• The Roman Space Telescope is expected to discover many more and provide valuable information about planetary systems beyond our Solar System.

Why are exoplanets important?

• The study of exoplanets helps scientists understand whether the planetary system around the Sun is unusual or whether similar systems are common throughout the galaxy.
• It can also contribute to the broader search for environments that may potentially support life, although finding an exoplanet does not automatically mean that life exists there.

Dark Matter and Dark Energy

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• One of the biggest mysteries in modern cosmology is that the matter we can directly observe forms only a small fraction of the universe.
• According to current estimates:

 

• • Ordinary matter – about 5%
  • Dark matter – about 27%
  • Dark energy – about 68%
• Dark matter and dark energy are therefore major components of the universe, but scientists still do not fully understand their physical nature.

Dark Matter

• Dark matter is a form of matter that cannot be directly observed through ordinary electromagnetic radiation because it does not appear to interact with light in the same way as ordinary matter.
• However, scientists have strong evidence for its existence from its gravitational effects.
• For example, the movement of stars within galaxies and the behaviour of galaxies and galaxy clusters cannot be fully explained by visible matter alone. The additional gravitational influence is attributed to dark matter.
• Role of dark matter- Dark matter is believed to:
  • Contribute significantly to the formation of galaxies.
  • Help hold galaxies and larger cosmic structures together.
  • Influence the movement of stars and galaxies.
  • Shape the large-scale distribution of matter in the universe.
• How will Roman study it?
  • Roman cannot directly photograph dark matter because dark matter does not emit or reflect light in the normal way.
  • Instead, it can study its gravitational influence on light and visible objects.
  • One important method is gravitational lensing.
  • By observing how the light from distant galaxies is distorted by intervening matter, scientists can estimate how matter—including dark matter—is distributed across the universe.
  • This can help produce a better picture of the cosmic web, the large-scale arrangement of galaxies and matter.

Dark Energy

• Dark energy is another poorly understood component of the universe.
• It is associated with the accelerating expansion of the universe.
• The universe has been expanding since the Big Bang.
• Observations indicate that this expansion is not simply continuing at a constant rate; rather, it is accelerating.
• Dark energy is the term used to describe whatever is responsible for this accelerated expansion.
• Why is dark energy important?
  • Understanding dark energy is important because it can help answer fundamental questions such as:
    • Why is the expansion of the universe accelerating?
    • Has the rate of expansion changed over cosmic history?
    • What is the ultimate fate of the universe?
    • Is our current understanding of gravity and cosmology complete?

Roman’s contribution

• Roman will observe huge numbers of galaxies across different distances and therefore different stages of cosmic history.
• By studying the distribution of galaxies and measuring how cosmic structures have evolved, scientists can better understand the relationship between gravity, matter and cosmic expansion.
• This will provide important evidence for testing different explanations of dark energy.

Significance of Studying Dark Matter and Dark Energy

• The study of dark matter and dark energy is important because together they account for the overwhelming majority of the universe’s estimated energy-matter content.
• Roman’s observations can improve our understanding of:
  • The large-scale structure of the universe.
  • How galaxies and galaxy clusters formed and evolved.
  • The distribution of matter across cosmic distances.
  • The history of the universe’s expansion.
  • The physical processes that have shaped the universe since the Big Bang.
• Thus, Roman is not merely searching for individual astronomical objects; it is also designed to understand the overall structure and evolution of the universe.

Gravitational Lensing

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• Gravitational lensing is one of the important techniques that Roman will use to study the universe.
• It is based on a prediction of Einstein’s General Theory of Relativity, massive objects can distort the fabric of spacetime and consequently bend the path of light.

How does it happen?

• Consider a distant galaxy whose light is travelling towards Earth.
• If another massive object, such as a galaxy or galaxy cluster, lies between that galaxy and Earth, the gravity of the intervening object can bend the light from the distant galaxy.
• As a result, the distant galaxy may appear:
  • Distorted
  • Magnified
  • Stretched
  • Shifted from its apparent position
• The massive object acting on the light is called the gravitational lens.

Why is it useful?

• Gravitational lensing allows scientists to study matter that cannot be directly seen.
• In particular, the amount and pattern of distortion can reveal information about the mass of the lensing object, including its dark matter component.
• Therefore, gravitational lensing provides an indirect method of mapping dark matter. 

Roman’s role

• Since Roman can observe large numbers of galaxies over wide areas, it can collect extensive data on weak gravitational lensing.
• By analysing tiny distortions in the shapes of distant galaxies, scientists can determine how matter is distributed across large regions of the universe.
• This will contribute to the study of:
  • Dark matter → distribution of matter → formation of galaxies → evolution of the universe

Lagrange Point 2 (L2)

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The Nancy Grace Roman Space Telescope will operate near Lagrange Point 2 (L2) of the Sun-Earth system, approximately 1.2 million km from Earth.

What are Lagrange Points? 

• Lagrange points are special locations in a two-body system where the gravitational effects of the two large bodies, combined with the orbital motion of a smaller object, allow the smaller object to maintain a relatively stable position with respect to the two bodies.
• There are five Lagrange points: L1, L2, L3, L4 and L5

Why is L2 important?

• L2 lies on the Sun-Earth line beyond Earth, on the side away from the Sun.
• From this region:
  • The Sun and Earth remain on broadly the same side of the spacecraft.
  • The telescope can maintain a favourable orientation for observations.
  • It can obtain a relatively stable and unobstructed view of deep space.
  • The location is particularly useful for space observatories that need stable observing conditions.
• The James Webb Space Telescope also operates near the Sun-Earth L2 region.

Major Instruments

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The Nancy Grace Roman Space Technology carries two major scientific instruments,

• Wide Field Instrument
• Coronagraph Instrument

They serve different but complementary purposes.

Wide Field Instrument

• The Wide Field Instrument (WFI) is a large infrared camera designed to survey extensive areas of the sky.
• It has around 300 megapixels, allowing it to collect large amounts of astronomical information in a single observation.
• Major features
  • Observes primarily in the infrared.
  • Has a very wide field of view.
  • Can capture a region of the sky about 1.5 times the apparent size of the full Moon.
  • Designed for large-scale astronomical surveys.
  • Can process images at a much faster rate than Hubble.
• Why is a wide field important?
• A telescope with a narrow field of view may provide highly detailed information about a small region of space.
• Roman is designed differently.
• Its wide field allows it to observe large portions of the sky efficiently.
• This is particularly useful when scientists want to:
  • Survey millions of galaxies.
  • Find large numbers of exoplanets.
  • Map the distribution of galaxies.
  • Study gravitational lensing.
  • Investigate the large-scale structure of the universe.
• Therefore, the Wide Field Instrument is central to Roman’s role as a wide-field astronomical survey telescope.

Coronograph

• A coronagraph is an instrument that blocks or suppresses the intense light coming from a star.
• This is important in the study of exoplanets because a star is generally far brighter than the planets orbiting it.
• The faint light reflected by a planet can therefore be overwhelmed by the much brighter light of its parent star.
• How does a coronagraph help?
  • The instrument suppresses the bright starlight, making it easier to detect the much weaker light coming from nearby objects.
• What can it help study?
  • The Coronagraph can help astronomers investigate:
    • Exoplanets
    • Planetary systems around other stars.
    • The environments surrounding stars.
    • Light reflected from planets.
• This is especially valuable for studying planets that are difficult to observe because of the brightness of their host stars.

UPSC Prelims Practice Question

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Consider the following statements regarding the Nancy Grace Roman Space Telescope:

1. It is designed to study dark matter, dark energy and exoplanets.
2. It will operate from Lagrange Point 2 of the Sun-Earth system.
3. Its Wide Field Instrument is an infrared camera capable of surveying a relatively large area of the sky.
4. Its coronagraph can help detect faint light from planets around bright stars.

Which of the statements given above are correct?

A) 1, 2and 3 only

B) 2, 3 and 4 only

C) 1, 3 and 4 only

D) 1, 2, 3 and 4

Answer: 1, 2, 3 and 4

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