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NASA engineers build Stopwatch to measure accurately Fraction of a billionth of Second

The timer is to be used for the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) scheduled for launch in 2018

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Washington, March 28, 2017: NASA engineers have built a stopwatch that can measure accurately fraction of a billionth of a second.

The timer is to be used for the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) scheduled for launch in 2018, NASA said.

ICESat-2 will use six green laser beams to measure height. With its incredibly precise time measurements, scientists can calculate the distance between the satellite and the Earth below, and from there record precise height measurements of sea ice, glaciers, ice sheets, forests and the rest of the planet’s surfaces.

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“Light moves really, really fast, and if you’re going to use it to measure something to a couple of centimetres, you’d better have a really, really good clock,” said Tom Neumann, ICESat-2’s Deputy Project Scientist.

If its stopwatch kept time even to a highly accurate millionth of a second, ICESat-2 could only measure elevation to within about 500 feet.

Scientists would not be able to tell the top of a five-storey building from the bottom. That does not cut it when the goal is to record even subtle changes as ice sheets melt or sea ice thins.

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To reach the needed precision of a fraction of a billionth of a second, engineers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, had to develop and build their own series of clocks on the satellite’s instrument — the Advanced Topographic Laser Altimeter System, or ATLAS.

This timing accuracy will allow researchers to measure heights to within about two inches, NASA said in a statement on Monday.

ATLAS pulses beams of laser light to the ground and then records how long it takes each photon to return.

This time, when combined with the speed of light, tells researchers how far the laser light travelled.

This flight distance, combined with the knowledge of exactly where the satellite is in space, tells researchers the height of the Earth’s surface below.

The stopwatch that measures flight time starts with each pulse of ATLAS’s laser. As billions of photons stream down to Earth, a few are directed to a start pulse detector that triggers the timer, said Phil Luers, Deputy Instrument System Engineer with the ATLAS instrument. (IANS)

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NASA’s Probe Discovers Signs Of Water on Asteroid Bennu

OSIRIS-REx will pass later this month just 1.2 miles (1.9 km) from Bennu, entering the asteroid's gravitational pull and analyzing its terrain.

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This Nov. 16, 2018, image provide by NASA shows the asteroid Bennu. NASA

NASA’s OSIRIS-REx spacecraft has discovered ingredients for water on a relatively nearby skyscraper-sized asteroid, a rocky acorn-shaped object that may hold clues to the origins of life on Earth, scientists said on Monday.

OSIRIS-REx, which flew last week within a scant 12 miles (19 km) of the asteroid Bennu some 1.4 million miles (2.25 million km) from Earth, found traces of hydrogen and oxygen molecules — part of the recipe for water and thus the potential for life — embedded in the asteroid’s rocky surface.

The probe, on a mission to return samples from the asteroid to Earth for study, was launched in 2016. Bennu, roughly a third of a mile wide (500 meters), orbits the sun at roughly the same distance as Earth. There is concern among scientists about the possibility of Bennu impacting Earth late in the 22nd century.

 

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NASA’s OSIRIS-REx. Flickr

 

“We have found the water-rich minerals from the early solar system, which is exactly the kind of sample we were going out there to find and ultimately bring back to Earth,” University of Arizona planetary scientist Dante Lauretta, the OSIRIS-REx mission’s principal investigator, said in a telephone interview.

Asteroids are among the leftover debris from the solar system’s formation some 4.5 billion years ago. Scientists believe asteroids and comets crashing into early Earth may have delivered organic compounds and water that seeded the planet for life, and atomic-level analysis of samples from Bennu could provide key evidence to support that hypothesis.

“When samples of this material are returned by the mission to Earth in 2023, scientists will receive a treasure trove of new information about the history and evolution of our solar system,” Amy Simon, a scientist at NASA’s Goddard Space Flight Center in Maryland, said in a statement.

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This illustration provided by NASA depicts the OSIRIS-REx spacecraft at the asteroid Bennu. The rocky remnant from the dawn of the solar system may hold clues to the origins of life. VOA

“We’re really trying to understand the role that these carbon-rich asteroids played in delivering water to the early Earth and making it habitable,” Lauretta added.

OSIRIS-REx will pass later this month just 1.2 miles (1.9 km) from Bennu, entering the asteroid’s gravitational pull and analyzing its terrain. From there, the spacecraft will begin to gradually tighten its orbit around the asteroid, spiraling to within just 6 feet (2 meters) of its surface so its robot arm can snatch a sample of Bennu by July 2020.

Also Read: Wintertime Ice Growth in Arctic Sea Slows Long-Term Decline: NASA

The spacecraft will later fly back to Earth, jettisoning a capsule bearing the asteroid specimen for a parachute descent in the Utah desert in September 2023. (VOA)