Cooling the Parker Solar Probe

[harrylentil]

This probe is designed to fly closer than 4 million miles from the sun's 'surface'. Is it possible in principle to cool the spacecraft 's inner facing surface by transferring heat to a cooler part and then radiating it into space from the far surface? I don't think it is equipped with such tech but it would be cool if it was.

 

[Bystander]

Sounds like a great exercise in "inverse square law" and "black-body" behavior to me; can you let us, PF, know what you come up with?

 

[Dale]

Is it possible in principle to cool the spacecraft 's inner facing surface by transferring heat to a cooler part and then radiating it into space from the far surface?

Yes. In principle it is possible to transfer heat throughout the probe so that it is roughly at the same temperature throughout. The rate of heating or cooling then depends on the principles of radiative heat transfer

 

[berkeman]

Maybe the probe will be rotating, continuing to turn a different side toward the Sun?

 

[harrylentil]

Can we make the assumptions that I want the spacecraft to have a main instrument chamber kept as cool as desired for a reasonably long time, and that it might be necessary to keep the craft with one side facing the sun (or a solution might require a rotation). So, to put numbers on it, if the near surface reaches 1,700 K the solution should require (1) the coolest part to kept at 300 K or (2) the coolest part to be kept at 3.5 K either until (a) the internal fuel runs out or (b) indefinitely.

 

[davenn]

Can we make the assumptions that I want the spacecraft to have a main instrument chamber kept as cool as desired for a reasonably long time, and that it might be necessary to keep the craft with one side facing the sun (or a solution might require a rotation). So, to put numbers on it, if the near surface reaches 1,700 K the solution should require (1) the coolest part to kept at 300 K or (2) the coolest part to be kept at 3.5 K either until (a) the internal fuel runs out or (b) indefinitely.

why make wild assumptions about the craft ??

All the main info is on the NASA site for you to read ... here's the main guts of the heat shielding ...

July 6, 2018

Cutting-Edge Heat Shield Installed on NASA’s Parker Solar Probe
The launch of Parker Solar Probe, the mission that will get closer to the Sun than any human-made object has ever gone, is quickly approaching, and on June 27, 2018, Parker Solar Probe’s heat shield — called the Thermal Protection System, or TPS — was installed on the spacecraft .

A mission 60 years in the making, Parker Solar Probe will make a historic journey to the Sun’s corona, a region of the solar atmosphere. With the help of its revolutionary heat shield, now permanently attached to the spacecraft in preparation for its August 2018 launch, the spacecraft ’s orbit will carry it to within 4 million miles of the Sun's fiercely hot surface, where it will collect unprecedented data about the inner workings of the corona.

The eight-foot-diameter heat shield will safeguard everything within its umbra, the shadow it casts on the spacecraft . At Parker Solar Probe’s closest approach to the Sun, temperatures on the heat shield will reach nearly 2,500 degrees Fahrenheit, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 85 degrees Fahrenheit.

The heat shield is made of two panels of superheated carbon-carbon composite sandwiching a lightweight 4.5-inch-thick carbon foam core. The Sun-facing side of the heat shield is also sprayed with a specially formulated white coating to reflect as much of the Sun’s energy away from the spacecraft as possible.

The heat shield itself weighs only about 160 pounds — here on Earth, the foam core is 97 percent air. Because Parker Solar Probe travels so fast — 430,000 miles per hour at its closest approach to the Sun, fast enough to travel from Philadelphia to Washington, D.C., in about one second — the shield and spacecraft have to be light to achieve the needed orbit.https://www.nasa.gov/feature/goddar...shield-installed-on-nasa-s-parker-solar-probe

Dave

 

[berkeman]

At Parker Solar Probe’s closest approach to the Sun, temperatures on the heat shield will reach nearly 2,500 degrees Fahrenheit, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 85 degrees Fahrenheit.

Wow! That's amazing. Do you know the expected/projected lifetime in solar orbit?

 

[davenn]

Do you know the expected/projected lifetime in solar orbit?

wellllllll ...
the best I have so far found is this ...
https://www.nasa.gov/content/goddard/parker-solar-probe-humanity-s-first-visit-to-a-star

In order to unlock the mysteries of the Sun's atmosphere, Parker Solar Probe will use Venus’ gravity during seven flybys over nearly seven years to gradually bring its orbit closer to the Sun. The spacecraft will fly through the Sun’s atmosphere as close as 3.8 million miles to our star’s surface, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before.

And I'm not completely sure how to interpret that ?
It sounds like...
1) it does 7 loops around the Sun and Venus and each of those loops brings it closer during those 7 years or
2) it uses Venus once as a boost to initially get it into a closer 7 year solar orbit ( where it doesn't loop around Venus any more )

I'm sort of going for #1, but am not sure ?

Dave

 

[davenn]

OK from wiki ...

Trajectory[edit]
The spacecraft trajectory will include seven Venus flybys over nearly seven years to gradually shrink its elliptical orbit around the Sun, for a total of 24 orbits.[1] The science phase will take place during those 7 years, focusing on the periods when the spacecraft is closest to the Sun. The near Sun radiation environment is predicted to cause both spacecraft charging effects, radiation damage in materials and electronics, and communication interruptions, so the orbit will be highly elliptical with short times spent near the Sun.[21]

so #1 in previous post is the plan

The trajectory requires high launch energy, so the probe will be launched on a Delta IV Heavy class launch vehicle and an upper stage based on the STAR-48B solid rocket motor.[21] Interplanetary gravity assists will provide further deceleration relative to its heliocentric orbit, which may result in a heliocentric speed record at perihelion.[3][22] As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s (120 mi/s), which will temporarily make it the fastest manmade object, almost three times as fast as the current record holder, Helios-B.[23][24][25] Like every object in an orbit, due to gravity the spacecraft will accelerate as it nears perihelion, then slow down again afterwards until it reaches its aphelion.

my bold = WOWD