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NASA Delays Launch of Solar Probe

The heat shield is made of a 4.5-inch thick carbon composite foam material between two carbon fibre face sheets

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NASA solar probe launch delayed. Pixabay
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NASA on Saturday scrubbed the scheduled launch of its historic small car-size probe to “touch the Sun” from Cape Canaveral Air Force Station in Florida.

The agency is now targeting Sunday for the launch of the spacecraft which is designed to NASAgo all the way to the Sun’s atmosphere, or corona — closer to the Sun than any spacecraft in history.

“This morning’s launch of @NASASun’s #ParkerSolarProbe was scrubbed. Launch teams will attempt to launch on Sunday morning,” NASA said in a tweet on Saturday.

The probe is named after Eugene Parker, a solar physicist who in 1958 first predicted the existence of the solar wind, the stream of charged particles and magnetic fields that flow continuously from the Sun.

Nestled atop a United Launch Alliance Delta IV Heavy — one of the world’s most powerful rockets — with a third stage added, Parker Solar Probe will blast off toward the Sun with a whopping 55 times more energy than is required to reach Mars.

Weighing just 635 kgs, it is a relatively light spacecraft, Andy Driesman, project manager for the mission at the Johns Hopkins University Applied Physics Laboratory in the US, said in an earlier statement issued by NASA.

NASA
This morning’s launch of @NASASun’s #ParkerSolarProbe was scrubbed. Launch teams will attempt to launch on Sunday morning. Flickr

“And it needs to be, because it takes an immense amount of energy to get to our final orbit around the Sun,” Driesman added.

Zooming through space in a highly elliptical orbit, the Parker Solar Probe will reach speeds of up to 700,000 kms per hour, setting the record for the fastest spacecraft in history.

During its nominal mission lifetime of just under seven years, the Parker Solar Probe will complete 24 orbits of the Sun — reaching within 3.8 million miles of the Sun’s surface at the closest approach.

In an orbit this close to the Sun, the real challenge is to keep the spacecraft from burning up.

You May Also Like to Read About The History of Curiosity Rover: Curiosity Rover Completes 6 Years On Mars: NASA

“Recent advances in materials science gave us the material to fashion a heat shield in front of the spacecraft not only to withstand the extreme heat of the Sun, but to remain cool on the backside,” said Adam Szabo, the mission scientist for the Parker Solar Probe at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The heat shield is made of a 4.5-inch thick carbon composite foam material between two carbon fibre face sheets.

At the Parker Solar Probe’s closest approach to the Sun, temperatures on the heat shield will reach nearly 1,371 degrees Celsius, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 29.4 degrees Celsius. (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)