NASA’s new mission to estimate impact of asteroids on Earth

NASA plans to launch a new mission in 2016 to find potentially hazardous asteroids and predict their impact threat to Earth.

NASA’s OSIRIS-REx asteroid sample return mission will arrive at RQ36 in 2018 and orbit the asteroid until 2021. By communicating continuously with a spacecraft in orbit around RQ36, the team will get a much better idea of the asteroid’s orbit.

“We expect OSIRIS-REx will enable us to make an estimate of the Yarkovsky force on RQ36 at least twice as precise as what’s available now,” says Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt.

The Yarkovsky effect happens simply because it takes time for things to heat up and cool down. Objects tend to be coldest just before dawn and warmest at mid-afternoon, after hours of illumination by the high Sun.

The team will use what it learns about the Yarkovsky effect on RQ36 to help estimate the effects on other asteroids, NASA said in a statement.

The key to all these strategies is to discover the asteroid well in advance of its impact date and attempt to deflect it early, according to Edward Beshore of the University of Arizona, Tucson, deputy principal investigator for OSIRIS-REx asteroid sample return mission.

One of the first things that would be done if an asteroid appeared to be on a collision course with Earth is to send a probe to the asteroid that might look very much like OSIRIS-REx, said Beshore.

OSIRIS-REx will determine if RQ36 is actually a rubble pile by orbiting it and revealing the subtle effects on the orbit from the gravity of any large and dense lumps within the asteroid.

A probe like OSIRIS-REx could map the internal structure of an asteroid this way, providing valuable information on where to target the deflection mechanism.

OSIRIS-REx will also determine the composition of RQ36 using remote measurements from both visible light and infrared spectrometers, and by collecting a sample of material from the asteroid’s surface and returning it to Earth for study.

Since the Yarkovsky effect may vary depending on the type of material and its distribution, a probe with OSIRIS-REx’s capability to map the surface composition will enable a more precise estimate of the effect on the asteroid’s orbit.

The mission will also provide critical experience navigating around asteroids.

According to NASA’s Near-Earth Object (NEO) programme, there are more than 1,300 “Potentially Hazardous Asteroids” (PHAs) ¿ objects at least 150 yards across with a very small chance of impacting us someday because their orbital paths take them close to Earth’s orbit.

Source:http://www.indianexpress.com/news/nasas-new-mission-to-estimate-impact-of-asteroids-on-earth/1071471/0

‘Ozone thinning has changed ocean circulation’

A hole in the Antarctic ozone layer has changed the way waters in the southern oceans mix, which scientists say could impact global climate change.

The situation has the potential to alter the amount of CO2 in the atmosphere, scientist say.

In a study, published in the journal Science, Darryn W Waugh and his team show that subtropical intermediate waters in the southern oceans have become “younger” as the upwelling, circumpolar waters have gotten “older” – changes that are consistent with the fact that surface winds have strengthened as the ozone layer has thinned.

“This may sound entirely academic, but believe me, it’s not,” said Waugh, of the Morton K Blaustein Department of Earth and Planetary Sciences at Johns Hopkins’ Krieger School of Arts and Sciences.

“This matters because the southern oceans play an important role in the uptake of heat and carbon dioxide, so any changes in southern ocean circulation have the potential to change the global climate,” Waugh said in a statement.

Researchers used measurements taken from the early 1990s to the mid-to-late 2000s of the amount of a chemical compound known as “chlorofluorocarbon-12,” or CFC-12, in the southern oceans.

CFC-12 was first produced commercially in the 1930s and its concentration in the atmosphere increased rapidly until the 1990s when it was phased out by the Montreal Protocol on substances that deplete the ozone layer.

Researchers were able to infer changes in how rapidly surface waters have mixed into the depths of the southern oceans.

Because they knew that concentrations of CFCs at the ocean surface increased in tandem with those in the atmosphere, they were able to surmise that the higher the concentration of CFC-12 deeper in the ocean, the more recently those waters were at the surface.

The inferred age changes – “younger” in the subtropics, “older” nearer the South Pole – are consistent with the observed intensification of surface westerly winds, which have occurred primarily because of the Antarctic ozone hole, suggesting that stratospheric ozone depletion is the primary cause of the changes in ocean ventilation.

Source: http://www.indianexpress.com/news/ozone-thinning-has-changed-ocean-circulation/1067962/0

US satellite lost in failed launch from Pacific

Sea Launch AG says a US communications satellite was lost after a booster rocket carrying it into space failed shortly after its launch from a floating platform in the Pacific.

The company said in a statement today the Intelsat 27 satellite was lost 40 seconds after the launch due to the failure of the Zenit-3SL rocket. The Boeing. Co-built spacecraft was launched yesterday from the Odyssey ocean platform.

Sea Launch AG President Kjell Karlsen said the cause of the failure is unknown and the company is working to evaluate it.

An affiliate of Russia’s RKK Energia state-controlled rocket manufacturer owns 95 per cent of stock in Sea Launch,

with the remainder being held indirectly by Boeing Co. and Norwegian Aker ASA. The Zenit booster is manufactured by Ukraine’s Yuzhmash rocket plant.

Source: http://www.indianexpress.com/news/us-satellite-lost-in-failed-launch-from-pacific/1067974/

ESA plans to build 3D printed Moon base

The European Space Agency (ESA) plans to set up a base on Moon by using a 3D printer to build it from lunar materials, scientists say.

Industrial partners including renowned architects Foster + Partners have joined with ESA to test the feasibility of 3D printing using lunar soil, the space agency said.

“Terrestrial 3D printing technology has produced entire structures. Our industrial team investigated if it could similarly be employed to build a lunar habitat,” said Laurent Pambaguian, who heads the project for ESA.

Foster + Partners devised a weight-bearing “catenary” dome design with a cellular structured wall to shield against micro-meteoroids and space radiation, incorporating a pressurised inflatable to shelter astronauts. A hollow closed-cell structure – reminiscent of bird bones – provides a good combination of strength and weight. The base’s design was guided in turn by the properties of 3D-printed lunar soil, with a 1.5 tonne building block produced as a demonstration.

“3D printing offers a potential means of facilitating lunar settlement with reduced logistics from Earth,” added Scott Hovland of ESA’s human spaceflight team.

“The new possibilities this work opens up can then be considered by international space agencies as part of the current development of a common exploration strategy.

“As a practice, we are used to designing for extreme climates on Earth and exploiting the environmental benefits of using local, sustainable materials,” said Xavier De Kestelier of Foster + Partners Specialist Modelling Group.

“Our lunar habitation follows a similar logic,” he said in a ESA Statement.

The UK’s Monolite supplied the D-Shape printer, with a mobile printing array of nozzles on a 6 m frame to spray a binding solution onto a sand-like building material.

3D “printouts” are built up layer by layer ¿ the company more typically uses its printer to create sculptures and is working on artificial coral reefs to help preserve beaches from energetic sea waves.

“First, we needed to mix the simulated lunar material with magnesium oxide. This turns it into “paper” we can print with,” said Monolite founder Enrico Dini.

“Then for our structural ‘ink’ we apply a binding salt which converts material to a stone-like solid.

“Our current printer builds at a rate of around 2 m per hour, while our next-generation design should attain 3.5 m per hour, completing an entire building in a week,” said Dini.

Source: http://www.indianexpress.com/news/esa-plans-to-build-3d-printed-moon-base/1067991/0