NASA’s Parker Solar Probe…the Spacecraft that would defy the Sun’s fury Part 2 of 3
NASA’s Parker
Solar Probe…the Spacecraft that would defy the Sun’s fury
Part
Two
By E. Stanley Ukeni
Since what NASA is attempting
to accomplish with the launch of the Parker Solar Probe, sounds like an
impossible mission, I would like to use this second part of my article to delve
into the advanced feat of engineering needed to keep the spacecraft from being
toasted by the scorching inferno of the sun’s corona.
Nicola Fox—the mission project
scientist at the Johns Hopkins University’s Applied Physics Laboratory, summed
up the importance of the remarkable engineering feat required to undertake this
unique solar exploration, during Wednesday, May 31st, 2017, press
briefing, with this telling remark, “Why has it taken us 60 years? The
materials didn’t exist to allow us to do it. We had to make a heat shield, and
we love it. Something that can withstand the extreme hot and cold temperature
shifts of its 24 orbits is revolutionary”.
This remark lets us know that
without the recent breakthroughs in engineering, this audacious mission would
still remain in the conceptual stages. I dare say that this ability for humans
to venture to a region of space that was previously inconceivable is a
testament of human scientific ingenuity.
It’s quite obvious that it
would take a specially designed and equipped spacecraft to safely venture into
the hellish inferno of the near-periphery of our host star. Well, NASA’s team
of engineers has been working tirelessly to create a spacecraft capable of
surviving the grueling interstellar voyage to the outer edges of our sun.
As most of us learnt from the
Greek mythical fable of Daedalus and Icarus, the Parker Solar Probe would
require special protection to keep its systems cool, if NASA wishes to avoid
the misfortune of Icarus from befalling the spacecraft, as it ventures into the
sun’s corona. Mindful that flying so close to the sun requires special
precautions, a dedicated team of NASA engineers to device an ingenious cooling
system and solar arrays for the spacecraft.
An eight-foot in diameter
shield, called the Thermal Protection System (TPS) will guard most of the
spacecraft’s components—including scientific instruments and avionics from the
scorching inferno that rage within the sun’s corona. The craft’s solar panels
will be the more exposed, and as such would require a robust and ingenious
cooling system to keep them from melting.
After extensive scientific
research and investigation, the Parker Solar Probe spacecraft engineers at the
John Hopkins’ Applied Physics Lab (APL) came to the conclusion that the
temperature range they required to cool the spacecraft’s solar panels was about
a range of 50 degrees Fahrenheit to 257 degrees Fahrenheit. After testing a
variety of coolants, they came to the informed conclusion that water was the
preferred coolant for the spacecraft’s coolant.
The spacecraft’s cooling system
is designed to maintain the solar panels at a functional 360 degrees Fahrenheit
or lower, even though the TPS will get as hot as 2,500 degrees Fahrenheit. This
will be achieved by pressurizing the water—which will raise its boiling point
above 257 degrees Fahrenheit. A deionization process will strip the water of
any minerals that could gum up the system. It is estimated that the solar
panels will receive 25 times the solar energy that the panels receive in Earth
orbit, while flying through the sun’s atmosphere.
The engineers at the John
Hopkins’ Applied Physics Lab used a standard cover of glass to protect the
photovoltaic cells as a special ceramic carrier soldered onto the bottom of
each cell. The ceramic substrate; called a platen, will then be glued on with a
thermally conductive adhesive. This should keep the panels from being destroyed
in the intense heat of the corona.
In other to keep the water
inside the cooling system from freezing in open space during the Solar Probe’s
voyage to the sun, and again, from boiling away once the spacecraft enters the
sun’s atmosphere, APL rocket scientists developed a heated accumulator tank
that holds five liters of water. The system will keep the water from freezing
until the spacecraft arrives at its destination, where atmospheric temperatures
will spike.
The cooling system is expected
to maintain a cooling capacity of 6,000 watts, as it is expected to undergo
massive temperature swings as it launches into the void of space and towards
the sun’s corona. To militate against these swings, the cooling system will
include two-speed pumps and four radiators made of titanium tubes with aluminum fins, which are a mere two
hundredths of an inch thick.
The Parker Solar Probe is
designed to independently carry out its mission objectives. In other to equip
the spacecraft with self-guidance artificial intelligence, APL engineers
equipped the spacecraft with a variety of systems—including wing angle control,
guidance and control, electrical power system, avionics, fault management,
autonomy and flight software. In fact, it is expected that the Parker Solar
Probe will be one of the most autonomous spacecraft ever launched.
You can access the Part Three of this post here
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Authored by E. Stanley Ukeni, ©
2017. All Rights Reserved. This material and other articles or stories posted
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Sources: Johns Hopkins University and NASA
Photo Credit: NASA
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