Saturday October 20, 2018

NASA’s OSIRIS-REx Spacecraft begins 2-week search for enigmatic class of near-Earth objects known as Earth-Trojan asteroids

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Aerial View of NASA. Wikimedia
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Washington, Feb 10, 2017: NASA said its OSIRIS-REx spacecraft has started a two-week search for an enigmatic class of near-Earth objects known as Earth-Trojan asteroids.

The mission, currently on a two-year outbound journey to the asteroid Bennu, will spend almost two weeks searching for evidence of these small bodies, the US space agency said on Thursday.

Although scientists have discovered thousands of Trojan asteroids accompanying other planets, only one Earth-Trojan has been identified to date, asteroid 2010 TK7.

Scientists predict that there should be more Trojans sharing Earth’s orbit but they are difficult to detect from Earth as they appear near the sun on the Earth’s horizon.

“So this search gives us a unique opportunity to explore the primordial building blocks of Earth,” said principal investigator Dante Lauretta of the University of Arizona, Tucson.

Trojan asteroids are trapped in stable gravity wells, called Lagrange points, which precede or follow a planet.

Launched on September 8, 2016, OSIRIS-REx is currently travelling through Earth’s fourth Lagrange point, which is located 60 degrees ahead in Earth’s orbit around the sun, about 150 million km from Earth.

The mission team will use this opportunity to take multiple images of the area with the spacecraft’s MapCam camera in the hope of identifying Earth-Trojan asteroids in the region.

“Because the Earth’s fourth Lagrange point is relatively stable, it is possible that remnants of the material that built Earth are trapped within it,” Lauretta said.

The operations involved in searching for Earth-Trojan asteroids closely resemble those required to search for natural satellites and other potential hazards around Bennu when the spacecraft approaches its target in 2018, NASA said. (IANS)

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Habitability Of Surrounding Planets Affected By Super Flares Of Red Dwarfs: NASA

Red dwarfs -- especially young red dwarfs -- are active stars, producing flares blast out energy

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NASA, space, red dwarf
Superflares from red dwarfs may affect habitability of planets Pixabay

Using NASA’s Hubble Space Telescope, astronomers have found that violent outbursts, or superflares, from red dwarf stars could affect the habitability of any planets orbiting it.

Young low-mass stars flare much more frequently and more energetically than old stars and middle-age stars like our Sun, the findings of the study published in the Astrophysical Journal showed.

The findings are based on observations of the flare frequency of 12 red dwarfs.

Hubble is observing such stars through a large programme called HAZMAT — Habitable Zones and M dwarf Activity across Time.

“M dwarf” is the astronomical term for a red dwarf star — the smallest, most abundant and longest-living type of star in our galaxy.

Hubble Telescope. red dwarf
Hubble Telescope. Flickr

The HAZMAT programme is an ultraviolet survey of red dwarfs at three different ages — young, intermediate, and old.

“The goal of the HAZMAT programme is to help understand the habitability of planets around low-mass stars,” explained the programme’s principal investigator, Evgenya Shkolnik from Arizona State University.

“These low-mass stars are critically important in understanding planetary atmospheres,” Shkolnik added.

Stellar flares from red dwarfs are particularly bright in ultraviolet wavelengths, compared with Sun-like stars.

Red dwarf  planet
Artist’s view of planets transiting red dwarf star in TRAPPIST-1 system. Flickr

Hubble’s ultraviolet sensitivity makes the telescope very valuable for observing these flares.

The flares are believed to be powered by intense magnetic fields that get tangled by the roiling motions of the stellar atmosphere.

When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy.

The team found that the flares from the youngest red dwarfs they surveyed — just about 40 million years old — are 100 to 1,000 times more energetic than when the stars are older.

This younger age is when terrestrial planets are forming around their stars.

Red dwarf
This illustration shows a red dwarf star orbited by a hypothetical exoplanet. NASA

About three-quarters of the stars in our Milky Way galaxy are red dwarfs. Most of the galaxy’s “habitable-zone” planets — planets orbiting their stars at a distance where temperatures are moderate enough for liquid water to exist on their surface — orbit red dwarfs.

In fact, the nearest star to our Sun, a red dwarf named Proxima Centauri, has an Earth-size planet in its habitable zone.

Also Read: NASA Plans For Science Payloads For Delivery To Moon

However, red dwarfs — especially young red dwarfs — are active stars, producing flares that could blast out so much energy that it disrupts and possibly strips off the atmospheres of these fledgling planets. (IANS)