Monday October 23, 2017
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Cassini mission discovers ‘lakes’ on Saturn’s moon Titan

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Washington: A study using data from the joint NASA and the European Space Agency (ESA) Cassini mission suggests the Saturn moon Titan’s surface indentation that is similar to creation of sinkholes on the Earth.

Apart from the Earth, Titan is the only body in the solar system known to possess surface lakes and seas, which have been observed by the Cassini spacecraft.

The team calculated how long it would take for patches of Titan’s surface to dissolve to create these features.

“We compared the erosion rates of organics in liquid hydrocarbons on Titan with those of carbonate and evaporite minerals in liquid water on Earth,” said Thomas Cornet of the European Space Agency.

“We found that the dissolution process occurs on Titan some 30 times slower than on Earth due to the longer length of Titan’s year and the fact it only rains during Titan summer. Nonetheless, we believe that dissolution is a major cause of landscape evolution on Titan and could be the origin of its lakes,” Cornet said.

These are terrestrial landscapes that result from erosion of dissolvable rocks such as limestone and gypsum, in groundwater and rainfall percolating through rocks.

Over time, this leads to features like sinkholes and caves in humid climates and salt-pans where the climate is more arid.

The rate of erosion creating such features depends on factors such as the chemistry of the rocks, the rainfall rate and the surface temperature.

While all of these aspects clearly differ between Titan and Earth, the researchers think the underlying process may be surprisingly similar.

“By comparing Titan’s surface features with examples on the Earth and applying a few simple calculations, we have found similar land-shaping processes that could be operating under very different climate and chemical regimes,” said Nicolas Altobelli, ESA’s Cassini project scientist. (IANS)

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Spacewalking Astronauts Replace Blurry Camera on Robot Arm

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This still image provided by NASA shows astronaut Joe Acaba during a spacewalk at the International Space Station on Oct. 20, 2017.

Astronauts went spacewalking Friday to provide some necessary focus to the International Space Station’s robot arm.

The main job for commander Randy Bresnik and teacher-turned-astronaut Joe Acaba was to replace a blurry camera on the new robotic hand that was installed during a spacewalk two weeks ago. The two men were supposed to go spacewalking earlier this week, but NASA needed extra time to rustle up the repair plan.

Sharp focus is essential in order for the space station’s robot hand to capture an arriving supply ship. The next delivery is a few weeks away, prompting the quick camera swap-out.

Orbital ATK, one of NASA’s commercial shippers, plans to launch a cargo ship from Virginia on November 11.

Acaba was barely outside an hour when he had to replace one of his safety tethers, which keep him secured to the orbiting outpost and prevent him from floating away.

Mission Control noticed his red tether seemed frayed and worn and ordered Acaba to “remain put” with his good waist tether locked to the structure as Bresnik went to get him a spare.

Spacewalking astronauts always have more than one of these crucial lifelines in case one breaks. They also wear a jetpack in case all tethers fail and they need to fly back to the space station.

This was the third spacewalk in two weeks for the space station’s U.S. residents. Bresnik performed the first two with Mark Vande Hei.

As they ventured out, Bresnik noted they were flying over Puerto Rico.

“Get out of here,” replied Acaba, the first astronaut of Puerto Rican heritage.

Acaba’s parents were born there, and he still has family on the hurricane-ravaged island.

“There’s a whole line of people looking up and smiling today as you get ready to head out the door,” Bresnik said.

Friday’s spacewalk should be the last one for the year. Early next year, astronauts will replace the hand on the opposite side of the 58-foot robot arm, Canada’s main contribution to the space station. The original latching mechanisms are showing wear and tear since the arm’s launch in 2001.

The 250-mile-high complex is currently home to three Americans, two Russians and one Italian.(VOA)

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NASA extends Dawn mission at dwarf planet Ceres

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Washington, Oct 20: NASA has approved a second extension of the Dawn mission at Ceres, the largest object in the asteroid belt between Mars and Jupiter.

During this extension, the spacecraft will descend to lower altitudes than ever before at the dwarf planet, which it has been orbiting since March 2015, the US space agency said on Thursday.

The spacecraft, which has already completed 10 years of spaceflight, will continue at Ceres for the remainder of its science investigation and will remain in a stable orbit indefinitely after its fuel runs out.

Dawn completed its prime mission in June 2016, and its first extension was also approved that year.

The Dawn flight team is studying ways to manoeuvre Dawn into a new elliptical orbit, which may take the spacecraft to less than 200 kilometres from the surface of Ceres at closest approach. Previously, Dawn’s lowest altitude was 385 kilometers.

A priority of the second Ceres mission extension is collecting data with Dawn’s gamma ray and neutron spectrometer, which measures the number and energy of gamma rays and neutrons, NASA said.

This information is important for understanding the composition of Ceres’ uppermost layer and how much ice it contains.

The spacecraft also will take visible-light images of Ceres’ surface geology with its camera, as well as measurements of Ceres’ mineralogy with its visible and infrared mapping spectrometer.

The extended mission at Ceres additionally allows Dawn to be in orbit while the dwarf planet goes through perihelion, its closest approach to the Sun, which will occur in April 2018.

Because of its commitment to protect Ceres from Earthly contamination, Dawn will not land or crash into Ceres.

Instead, it will carry out as much science as it can in its final planned orbit, where it will stay even after it can no longer communicate with Earth.

Mission planners estimate the spacecraft can continue operating until the second half of 2018.

Dawn is the only mission ever to orbit two extraterrestrial targets. It orbited giant asteroid Vesta for 14 months from 2011 to 2012, then continued on to Ceres, where it has been in orbit since March 2015.(IANS)

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NASA Running out of Fuel Required for Deep Space Missions : What will be the future of Exploration Missions?

The supply of the critical resource could be exhausted within the next decade, putting in jeopardy NASA's future missions that would require this fuel.

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What will happen to exploration missions if NASA runs out of fuel? Wikimedia

Washington, October 12, 2017 : The shortage of plutonium threatens NASA’s future mission to explore deep space, the US government has warned.

The break in production of plutonium 238 (Pu-238) between 1988 and 2015 could result in a bottleneck situation, where there is not enough of this scarce resource to power spacecraft during long-duration missions, Newsweek.com reported this week citing a government report.

NASA has long used radioisotope power systems (RPS) to generate reliable electrical power and heat energy for long-duration space missions, the US Government Accountability Office (GAO) report said.

But given NASA’s current plans for solar system exploration, the supply of this critical resource could be exhausted within the next decade, putting in jeopardy its future missions that would require this fuel, it warned.

RPS can operate where solar panels or batteries would be ineffective or impossible to use, such as in deep space or in shadowed craters, by converting heat from the natural radioactive decay of plutonium-238 (Pu-238) into electricity.

Missions such as Mars Curiousity rover and the Voyager 1 and 2 spacecraft use radioisotope thermoelectric generators as power source.

The production problems of Pu-238 and subsequent risks to NASA have been known for several years.

The Department of Energy (DOE) and its predecessor agencies have been providing Pu-238 and fabricating RPS for NASA and other federal agencies for more than five decades decades

ALSO READ NASA’S Mars Odyssey Spacecraft Captures First Images of the Martian Moon Phobos after 16 years

DOE currently maintains about 35 kgs of Pu-238 isotope designated for NASA missions, about half of which currently meets the power specifications for spaceflight.

However, given NASA’s current plans for solar system exploration, this supply could be exhausted within the next 10 years.

Specifically, NASA plans to use about 3.5 kg of Pu-238 isotope for one RPS to power the Mars 2020 mission, the Government Accountability Office report said.

NASA may also use an additional 10.5 kg of Pu-238 isotope for its New Frontiers #4
mission if three RPS are used.

If DOE’s existing Pu-238 supply is used for these two missions, NASA would be forced to eliminate or delay future missions requiring RPS until DOE produces or acquires more Pu-238, the report said. (IANS)