81–90 of 128 posts
> Particles may be moving fast (high temperature), but if there are very few of them, they won’t transfer much energy (low heat). Since space is mostly empty, there are very few particles that can transfer energy to the spacecraft. That explains why energy is not transferred by conduction or convection to the spacecraft. But what about energy (heat) transfer by radiation? Why won't the spacecraft get all the energy f…
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Doesn’t it undermine the credibility of NASA if something goes wrong? The public who is the audience for this article is also paying the bills (through taxes). I’d settle for just changing “won’t melt” to “shouldn’t melt”. I think that appropriate for something that’s never been attempted.
Either way we’re chucking lots of money at the sun so if it fails we still learn something, not to mention developed a lot of technologies along the way.
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There is usually a piece of software running on the machine which basically just does this - allows you to command an image upload to the SSD, do a checksum of the file, then install it if all goes well. There is also usually a simpler version of the software on a redundant SSD or partition which the onboard computer will install if it detects that the software that is currently installed is malfunctioning. My unders…
Thanks for the reply! So what you're saying is that it's just a "normal" over-the-air software update. I.e. you add some new functionality and then do a full system test of all functions of the software before replacing the entire image? That makes sense, but is almost a bit disappointing. After all, that is exactly how it works for the boring systems here on earth. From various wired & co articles I had the impressi…
There is also a way to send pre-programmed task lists to them which are executed sequentially, with delays if necessary.
That kind of thing is in the hands of operations, so it's not usually the job of the software team to test in the normal manner.
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There is usually a piece of software running on the machine which basically just does this - allows you to command an image upload to the SSD, do a checksum of the file, then install it if all goes well. There is also usually a simpler version of the software on a redundant SSD or partition which the onboard computer will install if it detects that the software that is currently installed is malfunctioning. My unders…
It makes sense when you think anout it. These missions last months even years before a specific piece of software becomes useful because it’s for a specifi part of the mission. Wouldn’t you want the benefit of those extra months to perfect the software?
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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…
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> Is there no possibility that manufacturer defects or a solar anomaly that could cause unexpected problems? There sure is. At least two of the systems (positioning and water cooling) are active systems that could fail. > but should we be so confident without actually having done something like this thousands of times? "we" are confident enough that we rely on it to protect a > 1 billion USD probe. What's the use in…
Doesn’t it undermine the credibility of NASA if something goes wrong? The public who is the audience for this article is also paying the bills (through taxes). I’d settle for just changing “won’t melt” to “shouldn’t melt”. I think that appropriate for something that’s never been attempted.
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Either way we’re chucking lots of money at the sun so if it fails we still learn something, not to mention developed a lot of technologies along the way.
For sure, but it would be a shame if NASA lost confidence and trust (and possibly funding) with their stakeholders (the public), because they weren’t more upfront about the potential risks. As a scientific organization that has experienced significant (and expensive) failures before, I expect better.
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.c…
http://earthsky.org/space/heat-shield-parker-solar-probe It appears the heat shield is a carbon sheet sandwich. At first I was guessing some form of tungsten-carbine, but that is the traditional material of NASA heat shields. > Why is the solar wind a breeze closer to the sun but a supersonic torrent farther away? Why is the corona itself millions of degrees hotter than the surface? I suspect the answer to all those…
"Why is the corona itself millions of degrees hotter than the surface? I suspect the answer to all those questions is simply gravity, but it will be nice to verify such things with data" Can you explain your hypothesis a bit?
The Sun has enormous gravity. It comprises 99.86% of the solar system's total mass. It would seem heat can be greater expressed where it is more free upon the vacuum of space upon escaping the gravity that confines the high density mass. https://en.wikipedia.org/wiki/Sun
As for solar wind momentum it would make sense that a particle is accelerating away from the Sun at a near constant energy that is less confined by gravity over distance... at least until it hits termination shock at the edge of the solar system.
Of course these are all speculations and hopefully the probe will provide the data to qualify more valid conclusions.
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Also, the cool side of the craft will stay cool by radiating its heat away into space.
When the heat flow trough the material reaches equilibrium, the back will radiate exactly as much heat as the front side receives. At that point the heat shield serves no purpose.
[0] https://www.electronics-cooling.com/1997/09/one-dimensional-...