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Flowing water filled Gale Crater on Mars: Indian-origin scientist

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Washington: Around 3.3-3.8 billion years ago, a series of streams and lakes existed on the Red Planet, filling the Gale Crater with sediment deposited as layers that formed the foundation for the mountain named Mouth Sharp, an Indian-origin scientist has revealed.

According to Ashwin Vasavada, project scientist with NASA’s Mars Science Laboratory (MSL), the Red Planet appears to have had a more massive atmosphere billions of years ago than it does today, with an active hydrosphere capable of storing water in long-lived lakes.

The MSL team has concluded that this water helped to fill Gale Crater, Curiosity’s landing site.

“Observations from Curiosity rover suggest that a series of long-lived streams and lakes existed at some point in the past, delivering sediment that slowly built up the lower layers of Mount Sharp,” explained Vasavada.

Using Curiosity data, MSL scientists have pieced together an increasingly coherent and compelling story about the evolution of this region of Mars.

Before Curiosity landed on Mars, scientists proposed that Gale Crater had filled with layers of sediments.

Some hypotheses implied that the sediments accumulated from wind-blown dust and sand whereas others focused on the possibility that sediment layers were deposited in ancient streams and lakes.

The latest results indicate that these wetter scenarios were correct for the lower portions of Mount Sharp.

“During the traverse of Gale, we have noticed patterns in the geology where we saw evidence of ancient fast-moving streams with coarser gravel as well as places where streams appear to have emptied out into bodies of standing water,” Vasavada emphasised.

The prediction was that we should start seeing water-deposited, fine-grained rocks closer to Mount Sharp.

“Now that we have arrived, we are seeing finely laminated mud-stones in abundance. These silty layers in the strata are interpreted as ancient lake deposits,” he pointed out.

“These finely laminated mud-stones are very similar to those we see on Earth,” added Woody Fischer, professor of geobiology and coauthor of the paper.

The mud-stones indicates the presence of bodies of standing water in the form of lakes that remained for long periods of time, possibly repeatedly expanding and contracting during hundreds to millions of years.

These lakes deposited the sediment that eventually formed the lower portion of the mountain.

A lingering question surrounds the original source of the water that carried sediment into the crater.

For flowing water to have existed on the surface, Mars must have had a thicker atmosphere and warmer climate.

Curiosity has been exploring Gale Crater since August 2012.

In mid-September 2014, the rover reached the foothills of Mount Sharp. Curiosity has been exploring the base of the mountain since then.

The new findings were published in the journal Science.

(IANS)

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The Secret Behind NASA’s Parker Solar Probe

The spacecraft, launched from Cape Canaveral Air Force Station in Florida on August 12, will transmit its first scientific observations in December.

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Why won't NASA's Parker Solar Probe melt?
Why won't NASA's Parker Solar Probe melt?VOA

With NASA launching a historic Parker Solar Probe deeper into the solar atmosphere than any mission before it, a moot question arises: Why won’t it melt?

Inside the solar atmosphere — a region known as the corona — the probe will provide observations of what drives the wide range of particles, energy and heat that course through the region.

The spacecraft will travel through material with temperatures greater than several million degrees Celsius while being bombarded with intense sunlight.

According to the US space agency, Parker Solar Probe has been designed to withstand the extreme conditions and temperature fluctuations for the mission.

“The key lies in its custom heat shield and an autonomous system that helps protect the mission from the Sun’s intense light emission, but does allow the coronal material to ‘touch’ the spacecraft,” NASA said in a statement.

Parker solar probe
The spacecraft, launched from Cape Canaveral Air Force Station. IANS

While the Parker Solar Probe will travel through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 1,400 degree Celsius.

This is because “in space, the temperature can be thousands of degrees without providing significant heat to a given object or feeling hot. Since space is mostly empty, there are very few particles that can transfer energy to the spacecraft”.

The corona through which the Parker Solar Probe flies, for example, has an extremely high temperature but very low density.

The probe makes use of a heat shield known as the Thermal Protection System, or TPS, which is eight feet in diameter and 4.5 inches thick.

Those few inches of protection mean that just on the other side of the shield, the spacecraft body will sit at a comfortable 30 degrees Celsius.

Parker-Solar-2, NASA
The Parker Solar Probe sits in a clean room at Astrotech Space Operations in Titusville, Fla., after the installation of its heat shield. VOA

The TPS was designed by the Johns Hopkins Applied Physics Laboratory, and was built at Carbon-Carbon Advanced Technologies, using a carbon composite foam sandwiched between two carbon plates.

This lightweight insulation will be accompanied by a finishing touch of white ceramic paint on the sun-facing plate, to reflect as much heat as possible.

“Tested to withstand up to 1,650 degrees Celsius, the TPS can handle any heat the Sun can send its way, keeping almost all instrumentation safe,” said NASA.

Another challenge came in the form of the electronic wiring — most cables would melt from exposure to heat radiation at such close proximity to the Sun.

To solve this problem, the team grew sapphire crystal tubes to suspend the wiring, and made the wires from the chemical element niobium.

NASA
Several other designs on the spacecraft keep Parker Solar Probe sheltered from the heat.Flickr

Several other designs on the spacecraft keep Parker Solar Probe sheltered from the heat.

Without protection, the solar panels — which use energy from the very star being studied to power the spacecraft — can overheat.

At each approach to the Sun, the solar arrays retract behind the heat shield’s shadow, leaving only a small segment exposed to the Sun’s intense rays.

Also Read: Red-hot Voyage to Sun Will Bring us Closer to our Star

The solar arrays have a surprisingly simple cooling system: a heated tank that keeps the coolant from freezing during launch, two radiators that will keep the coolant from freezing, aluminium fins to maximise the cooling surface, and pumps to circulate the coolant.

The spacecraft, launched from Cape Canaveral Air Force Station in Florida on August 12, will transmit its first scientific observations in December. (IANS)