Debris from anti-satellite test no danger to ISS, India says

The Indian Space Research Organisation's (ISRO) Polar Satellite Launch Vehicle (PSLV-C45) launches India's Electromagnetic Spectrum Measurement satellite 'EMISAT' -- along with 28 satellites from other countries including Lithuania, Spain, Switzerland and the US -- at the Satish Dhawan Space Centre in Sriharikota, in Andhra Pradesh state, on April 1, 2019. (AFP)
Updated 07 April 2019
0

Debris from anti-satellite test no danger to ISS, India says

  • The danger from “space junk” is not that it falls to Earth but that it collides with orbiting satellites
  • These includes about 10,000 pieces of space debris, of which nearly 3,000 were created by a Chinese anti-satellite test

NEW DELHI: India insisted Saturday that debris from its anti-satellite missile test was not a danger to the International Space Station, in a rebuff to criticism from the US space agency.
India has been on the defensive following the March 27 test that NASA branded a “terrible thing” that had created new dangers for astronauts aboard the International Space Station.
“The mission had been designed in a away that debris decays very fast and that minimal debris goes up,” G. Satheesh Reddy, head of India’s Defense Research and Development Organization told reporters.
“There was a risk for 10 days and we have crossed that period,” he told a press conference.
“As per our simulations, there were no possibilities of hitting the International Space Station with debris from the satellite,” he added.
NASA chief Jim Bridenstine last week condemned India’s destruction of the satellite as a “terrible thing” that created 400 pieces of orbital debris, or “space junk.”
The danger from “space junk” is not that it falls to Earth but that it collides with orbiting satellites.
Even the smallest piece of debris traveling at great speeds can put a satellite out of action.
The Indian satellite was destroyed at a relatively low altitude of 300 kilometers (180 miles), 120 kilometers below the ISS and most orbiting satellites.
Bridenstine and other space experts also said the risk from the Indian debris would dissipate as much of it would burn up as it entered the atmosphere.
The US military tracks objects in space to predict the collision risk for the ISS and satellites. They are currently tracking 23,000 objects larger than 10 centimeters.
These includes about 10,000 pieces of space debris, of which nearly 3,000 were created by a Chinese anti-satellite test.
India has hailed the test as a sign that it is a space power. Only the United States, Russia and China had previously carried out successful anti-satellite missile strikes in space.


NASA probe detects likely ‘marsquake’ — an interplanetary first

A life-size model of the spaceship Insight, NASA's first robotic lander dedicated to studying the deep interior of Mars, is shown at Jet Propulsion Laboratory (JPL) in Pasadena, California, U.S. November 26, 2018. (REUTERS)
Updated 24 April 2019
0

NASA probe detects likely ‘marsquake’ — an interplanetary first

  • A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said

CALIFORNIA: NASA’s robotic probe InSight has detected and measured what scientists believe to be a “marsquake,” marking the first time a likely seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory in California reported on Tuesday.
The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.
The faint rumble characterized by JPL scientists as a likely marsquake, roughly equal to a 2.5 magnitude earthquake, was recorded on April 6 — the lander’s 128th Martian day, or sol.
It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.
“We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology,” InSight principal investigator Bruce Banerdt said in a news release.
Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.
“The high frequency level and broad band is very similar to what we get from a rupture process. So we are very confident that this is a marsquake,” Philippe Lognonné, a geophysics and planetary science professor at University Paris Diderot in France and lead researcher for InSight’s seismometer, said in an email.
Still, a tremor so faint in Southern California would be virtually lost among the dozens of small seismic crackles that occur there every day.
“Our informed guesswork is that this a very small event that’s relatively close, maybe from 50 to 100 kilometers away” from the lander, Banerdt told Reuters by telephone.
A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said.
 
The size and duration of the marsquake also fit the profile of some of the thousands of moonquakes detected on the lunar surface between 1969 and 1977 by seismometers installed there by NASA’s Apollo missions, said Lori Glaze, planetary science division director at NASA headquarters in Washington.
The lunar and Martian surfaces are extremely quiet compared with Earth, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.
Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.
Three other apparent seismic signals were picked up by InSight on March 14, April 10 and April 11 but were even smaller and more ambiguous in origin, leaving scientists less certain they were actual marsquakes.
Lognonné said he expected InSight to eventually detect quakes 50 to 100 times larger than the April 6 tremor.