NASA solar probe faces hellish heat, particle blasts to touch the sun

An
artist’s concept of NASA’s $1.5-billion Parker Solar Probe
mission passing by the sun.

NASA/Johns
Hopkins APL/Steve Gribben

• NASA‘s Parker Solar Probe is
  scheduled to launch Saturday, August 11 around 3:33 a.m.
  EDT.
• To “touch” the sun and study its weather, the
  $1.5-billion mission must survive hellish conditions.
• Temperatures will reach a searing 2,500 degrees when
  the spacecraft zooms through the star’s
  atmosphere at 430,000 mph.
• Once the probe runs out of fuel, pretty much everything
  but its carbon heat shield will be destroyed.

Touching a star isn’t easy. The sun is an enormous, searing-hot
orb of plasma that generates a chaos of magnetic fields and can
unleash deadly blasts of particles at a moment’s notice.

But that is precisely what NASA plans to do — 24 times or more —
with its car-size Parker Solar Probe (PSP). The
goal of the $1.5-billion mission is to edge within 4 million
miles of the sun, which is close enough to study the star’s
mysterious
atmosphere, solar wind, and other properties.

Information gathered by the probe may help space weather
forecasters better predict violent solar outbursts that can

overwhelm electrical grids, harm satellites,
disrupt electronics, and possibly lead to
trillions of dollars‘ worth of damage.

The spacecraft is slated to launch from the Florida coast on
Saturday at 3:33 a.m. EDT, should weather cooperate, though NASA
can wait as late as August 23 to fire off its probe. PSP will
reach the sun a few months later.

Here are some of the brutal conditions and tremendous challenges
NASA’s probe will have to survive to pull off its unprecedented
mission.

The tricky process of touching a star

The
orbital path that NASA’s Parker Solar Probe will have to fly to
“touch” the sun.

Johns
Hopkins University Applied Physics
Laboratory

The first hurdle PSP needs to clear is Earth itself.

To make the trip, the probe will ride atop a
Delta 4 Heavy rocket, which is one of the most powerful
operational launch vehicles on Earth (though not quite as
powerful as SpaceX’s new
Falcon Heavy system).

NASA chose the rocket because it’s surprisingly hard to get to
the sun, which is 93 million miles away.

Earth orbits the sun at a speed of 67,000 mph, and so does
anything launched off of the planet. To fall toward the sun, PSP
will have to slow down by 53,000 mph, NASA said in a video about its mission.

Three different rocket stages (one firing after the other runs
out of fuel) in the Delta 4 Heavy will help considerably with
boosting PSP toward that goal, but it’s not enough to repeatedly
fly the probe close to the sun.

Instead, the rocket will shoot the probe on a path toward Venus,
a planet it will fly past seven times over six years. The world’s
strong gravitational field will help gradually absorb PSP’s
“sideways motion” imparted by Earth and direct it closer and
closer to the sun.

The consequence of this orbital dance is that PSP will fall
toward the sun faster and faster after each pass. On its first
orbit of the sun in November 2018, the probe will be some 15.4
million miles from the sun. About 21 orbits later, in December
2024, it will sneak within 4 million miles of the sun, traveling
at a speed of nearly 430,000 mph relative to the star.

Achieving such a velocity would make PSP the fastest a human
object in space. It’s nearly 120 miles per second — fast enough
to fly from New York to Tokyo in less than a minute — and 3.3
times as fast as
NASA’s Juno spacecraft, which zips past Jupiter at speeds of
130,000 mph.

How to fly through hell and back

NASA’s
Parker Solar Probe must withstand blistering temperatures and
incredible speeds near the sun.
David
McNew/Getty Images; NASA; JHUAPL; Jenny Cheng/Business
Insider

During its journey, PSP must withstand sunlight 3,000 times more
powerful than occurs at Earth. Outside the spacecraft, in the
outer fringes of the sun’s corona or atmosphere, temperatures may
reach 2,500 degrees Fahrenheit — hot enough to liquify steel.

The probe also must contend with a “solar wind” of charged,
high-energy particles that can mess with electronics.

The key to protecting the probe, as well as its sensors for
measuring the sun’s magnetic fields and solar wind, is a special
heat shield called the Thermal Protection System.

The
carbon-foam-and-composite heat shield of NASA’s Parker Solar
Probe is craned into place atop the spacecraft on June 27,
2018.

NASA

Made of 4.5 inches of carbon foam sandwiched between two sheets
of carbon composites, the eight-feet-wide shield will absorb and
deflect solar energy that might otherwise fry the probe. A water
cooling system will also help prevent the spacecraft’s solar
panels from roasting and keep the spacecraft a cozy 85 deg F.

PSP’s mission is to crack two 60-year-old mysteries: why the sun
has a solar wind at all, and how the corona — the star’s outer
atmosphere — can heat up to millions of degrees. Both factors are
key to understanding what leads to potentially devastating solar
storms.

“That defies the laws of nature. It’s like water rolling uphill,”
Nicola Fox, a solar physicist at the Johns Hopkins University
Applied Physics Laboratory, said during a NASA briefing in 2017.

“Until you actually go there and touch the sun, you can’t answer
these questions,” said Fox, who’s a project scientist for the new
mission.

You can watch the Parker Solar Probe launch toward the sun on
Saturday, August 11, around 3 a.m. EDT via NASA
TV.

The probe’s mission will end many years from now, after it runs
out of the propellant it needs to keep its heat shield pointed at
the sun. When that happens, the star’s blistering heat will burn
up “90% of the spacecraft,” science writer Shannon Stirone
said on Twitter — but not the
heat shield itself.

“The heat shield will then orbit the sun for millions of years,”
she said.