GS Paper: GS3-17.Awareness in the fields of IT, Space, Computers, Robotics, Nano-technology, Bio-technology and issues relating to Intellectual Property Rights.

At 100 light-years from Earth, a low-mass star was sending signals in a pattern that suggested that an exoplanet was orbiting the star confirmed the Habitable-zone Planet Finder (HPF).

Habitable-zone Planet Finder

• NASA’s Kepler mission observed a dip in the host star’s light, suggesting that the planet was crossing in front of the star during its orbit.
• To confirm, researchers turned to an instrument called Habitable-zone Planet Finder (HPF). It has confirmed that there is indeed an exoplanet.
• HPF is an astronomical spectrograph, built by Penn State University scientists, and recently installed on the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas.
• The instrument is designed to detect and characterize planets in the habitable zone — the region around the star where a planet could sustain liquid water on its surface — around nearby low-mass stars.
• The newly confirmed planet, called G 9-40b, is the first one validated by HPF. It is about twice the size of Earth and orbits its star once every six Earth-days.

How it works

• A spectrograph is an instrument that splits light into its component wavelengths.
• Scientists then measure the properties of light over a specific portion of the spectrum and draw conclusions on what is responsible for the trends they observe.

Why need HPF?

• Kepler’s observations alone were not enough to confirm a planet. It was possible that a close stellar companion was responsible for the dip in the star’s light.
• Precision spectroscopic observations from HPF ruled out this possibility.
• Shooting a high-power laser into the air, researchers generated a “laser guide star”, and subsequent observations found no evidence of blending of light or other stellar companions.
• Finally, using HPF, an analysis of a set of radial velocities helped provide estimates for the planet’s mass.

NASA’s Parker Solar Probe launched on August 12, 2018 has completed its fourth close approach — called perihelion very recently, whizzing past at about 3.93 lakh km/h, at a distance of only 18.6 million km from the Sun’s surface.

Aditya L1: Exciting ahead

• The ISRO is preparing to send its first scientific expedition to study the Sun.
• Named Aditya-L1, the mission, expected to be launched early next year, will observe the Sun from a close distance, and try to obtain information about its atmosphere and magnetic field.
• ISRO categorizes Aditya L1 as a 400 kg-class satellite that will be launched using the Polar Satellite Launch Vehicle (PSLV) in XL configuration.
• The space-based observatory will have seven payloads (instruments) on board to study the Sun’s corona, solar emissions, solar winds and flares, and Coronal Mass Ejections (CMEs), and will carry out round-the-clock imaging of the Sun.
• Aditya L1 will be ISRO’s second space-based astronomy mission after AstroSat, which was launched in September 2015.

What is L1?

• L1 refers to Lagrangian/Lagrange Point 1, one of five points in the orbital plane of the Earth-Sun system.
• Lagrange Points, named after Italian-French mathematician Josephy-Louis Lagrange, are positions in space where the gravitational forces of a two-body system (like the Sun and the Earth) produce enhanced regions of attraction and repulsion.
• These can be used by spacecraft to reduce fuel consumption needed to remain in position.
• The L1 point is home to the Solar and Heliospheric Observatory Satellite (SOHO), an international collaboration project of NASA and the European Space Agency (ESA).
• The L1 point is about 1.5 million km from Earth, or about one-hundredth of the way to the Sun.

But why is studying the Sun important?

• Every planet, including Earth and the exoplanets beyond the Solar System, evolves — and this evolution is governed by its parent star.
• The solar weather and environment, which is determined by the processes taking place inside and around the sun, affects the weather of the entire system.
• Variations in this weather can change the orbits of satellites or shorten their lives, interfere with or damage onboard electronics, and cause power blackouts and other disturbances on Earth.
• Knowledge of solar events is key to understanding space weather.
• To learn about and track Earth-directed storms, and to predict their impact, continuous solar observations are needed.
• Every storm that emerges from the Sun and heads towards Earth passes through L1, and a satellite placed in the halo orbit around L1 of the Sun-Earth system has the major advantage of continuously viewing the Sun without any occultation/eclipses.

Why are solar missions challenging?

• What makes a solar mission challenging is the distance of the Sun from Earth (about 149 million km on average, compared to the only 3.84 lakh km to the Moon).
• More importantly the super hot temperatures and radiations in the solar atmosphere make it difficult to study.
• NASA’s Parker Solar Probe has already gone far closer — but it will be looking away from the Sun.
• The earlier Helios 2 solar probe, a joint venture between NASA and space agency of erstwhile West Germany, went within 43 million km of the Sun’s surface in 1976.

Problem of Heat

• The Parker Solar Probe’s January 29 flyby was the closest the spacecraft has gone to the Sun in its planned seven-year journey so far.
• Computer modelling estimates show that the temperature on the Sun-facing side of the probe’s heat shield, the Thermal Protection System, reached 612 degrees Celsius, even as the spacecraft and instruments behind the shield remained at about 30°C, NASA said.
• During the spacecraft’s three closest perihelia in 2024-25, the TPS will see temperatures around 1370°C.

Hurdles for Aditya L1

• It will stay much farther away, and the heat is not expected to be a major concern for the instruments on board. But there are other challenges.
• Many of the instruments and their components for this mission are being manufactured for the first time in the country, presenting as much of a challenge as an opportunity for India’s scientific, engineering, and space communities.
• One such component is the highly polished mirrors which would be mounted on the space-based telescope.
• Due to the risks involved, payloads in earlier ISRO missions have largely remained stationary in space; however, Aditya L1 will have some moving components, scientists said.