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Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

nasa.gov

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Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#51

Post by MichaelMoser123 »

implements wrote: post #18
MichaelMoser123 wrote: post #8

>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 niobium. are these wires on the outside of the spacecraft? but what about the silicon of all the electronic stuff that this thing must be keeping? The cooling…

Not a scientist, but I assume using "radiative heat transfer" ie a hot surface shielded from the sun emitting thermal radiation away from the spacecraft.

Yes, but the shield would have two sides, where one of them is facing the sun.

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#52

Post by kevin_thibedeau »

rtkwe wrote: post #38
marsRoverDev wrote: post #22

Earlier quoted context omitted.

This redundant software and hardware setup typically isn't necessary when humans aren't involved. The space shuttle system is similar to what you will find on a Boeing or Airbus aircraft. Redundant software, written by different people in different countries with completely different cultures in different languages (on purpose), running on multiple machines with different hardware and voting on the decisions to be ma…

They don't do 3x calculations and voting but they do often have redundant computers they can switch over to in case of failure. Curiosity had to switch to it's 'B-side' computer back in 2013 when A-side had a memory issue. Even when not carrying humans it's still a billion/million dollar mission that probably wouldn't be replicated for a while if ever (within the researchers life times at least) that could be scuttle…

Most spacecraft have some form of redundancy to guard against single point failures. It's a waste of money to send up failure prone hardware. Amateurs building cubesats, probably not, but the big players aren't going to take that sort of risk.

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#53

Post by gdubs »

firebacon wrote: post #27
JonoW wrote: post #10

>This all has to happen without any human intervention, so the central computer software has been programmed and extensively tested to make sure all corrections can be made on the fly. I'd love to get some deeper insight into how NASA writes and tests software, I can only guess it's a million miles from how most of us work. Anyone know of any good talks, articles from engineers there?

The part that I find the most intriguing is "corrections can be made on the fly". I can see how you would ensure reliability through proper requirements specification, a good software development process, separate independent implementations and extensive verification. However, every time I read a popsci article about space flight software, they talk about this capability to push new code to the spacecraft while it i…

http://www.flownet.com/gat/jpl-lisp.html

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#54

Post by sebazzz »

mpweiher wrote: post #7
guidedlight wrote: post #5

Earlier quoted context omitted.

Exactly. Stick your hand into an oven at 100 celsius ...OR... Stick your hand into into a pot of water at 100 celsius. The difference is that the water molecules are more tightly packed, than the air molecules in the oven. In space, they are quite far apart.

> Stick your hand into into a pot of water at 100 celsius ..and: please don't! :)

Fast reflexes will prevent major damage. It won't prevent pain though.

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#55

Post by firebacon »

gdubs wrote: post #53
firebacon wrote: post #27

Earlier quoted context omitted.

The part that I find the most intriguing is "corrections can be made on the fly". I can see how you would ensure reliability through proper requirements specification, a good software development process, separate independent implementations and extensive verification. However, every time I read a popsci article about space flight software, they talk about this capability to push new code to the spacecraft while it i…

http://www.flownet.com/gat/jpl-lisp.html

Thanks - that was exactly the kind of info I was looking for!

Amazing that they had the ability to just run ad-hoc LISP on the spacecraft. It appears their method to ensure safety in the face of arbitrary code execution was to divide up the spacecraft into isolation zones and run the parts that have a REPL on a non-essential CPU. From [1]:

> To protect the main DS-1 mission from possible misbehaviors of RA, the design included a “safety net” that allowed the RA experiment to be completely disabled with a single command, issued either from the ground or by on-board fault protection.

[1] https://ti.arc.nasa.gov/m/pub-archive/176h/0176%20(Havelund)...

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#57

Post by jccooper »

The part of the answer here that NASA always seems to skip (perhaps because it's not as fun as talking about all the cool heat-resistant technology) is that the vehicle is in an orbit that will only take it into the corona for a short time. While the closest approach is very close, its aphelion is (at closest) about the orbit of Venus. This gives it time to cool down after each corona encounter.

https://www.youtube.com/watch?v=cMNQeCWT09A

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#59

Post by trgv »

nextstep wrote: post #58

Inches? A yard stick? Millions of degrees Fahrenheit? I’m American and I’m embarrassed by this. This is science, make it easy for people to understand. Use SI units, please.

It's written for a general American audience so it makes sense to use those units.

Re: Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

#60

Post by kenjackson »

guidedlight wrote: post #5
hliyan wrote: post #2

As I understand, temperature is a measure of how fast atoms and molecules are vibrating, and not a measure of how much energy per unit area of contact can be transferred in a unit time.

Exactly. Stick your hand into an oven at 100 celsius ...OR... Stick your hand into into a pot of water at 100 celsius. The difference is that the water molecules are more tightly packed, than the air molecules in the oven. In space, they are quite far apart.

Is that also a reason that you feel warmer in high humidity heat?
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