Since getting that close takes a lot of DeltaV and I was curious:
>The Parker Solar Probe mission design uses repeated gravity assists at Venus to incrementally decrease its orbital perihelion to achieve a final altitude (above the surface) of approximately 8.5 solar radii, or about 6×106 km (3.7×106 mi; 0.040 au).[35] 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 near Sun radiation environment is predicted to cause 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.[34]
Highly elliptical orbits are cheaper to achieve anyway, right? You can get into one directly from your Venus gravity assists, and not have to keep precious fuel to transfer to a circular orbit later on.
As a bonus in this particular case, it limits your time in the higher temperatures of the corona; the spacecraft gets time to radiate heat and cool off before the next skim through.
It was meant to be 6×10^6 -- as a quick soundness check, the sun's radius is significantly more than 75 km (636 / 8.5) -- though I agree it would probably have been more reasonable to just write "6 million km"
Relevant part: the capturing cups are of metals with high melting points, plus
> The corona through which Parker Solar Probe flies, for example, has an extremely high temperature but very low density. Think of the difference between putting your hand in a hot oven versus putting it in a pot of boiling water
And for the rest of the craft there is a highly reflective heat shield.
Also spending most of it's orbit pretty far away from the sun. You can move your hand though an open flame with no issues, but if you keep it in the flame it will get burned.
You got it actually, it's all about how long you leave your hand in. And that is why the probe has a very elliptical orbit, so it "touches" the sun briefly and goes back out into space to cool down.
Temperature is not what burns you, it's heat flow that does the burning. A boiling pot has a lot of molecules densely packed together, so heat transfer happens fast. The air inside the oven is hot but will not be as effective in transferring heat to your hand. There is more "thermal resistance" between your hand and the air inside the oven than your hand and the water inside a boiling pot.
Imagine sticking your hand in the oven for 1 second. Now imagine sticking it in a pot of boiling water for 1 second. One you do every day, the other is an immediate trip to the hospital. What’s the difference? Water is far more dense than the air in the oven thus will transfer much more heat to your hand over that same duration.
> if I was in the oven, I'll burn and die there too.
Eventually. Not momentarily.
It would take you much longer to die in the oven than if you would dive into boiling water. I didn't tried both so I cannot be sure, but I suspect that one can live in a boiling water just for a several seconds, while it is possible to live a few tenths of seconds in the oven.
Finnish saunas regularly go to 100°C (210F). I can personally attest that fifteen minutes in dry 100°C air is very survivable, you just get sweaty. Meanwhile 100°C water burns you almost instantly.
Though it's worth noting that when talking about humans in air the humidity plays a huge role. Sweat cools your body through evaporative cooling, which works better the drier the air is. At 100% relative humidity you can't cool down and eventually overheat, at 10% humidity we can survive some ridiculous temperatures for as long as we can keep sweating.
Yes, some sauna's need you to wear the key of your dressing locker on an arm bracelet. While relaxing nicely in the heat you can instantly burn yourself severely the moment the iron part of the key presses into your skin. (Talking from experience here)
The vacuum probably also helps. I'd also expect a few mm of vacuum might do the trick of avoiding contracting covid, though I'd not (as the Dutch say) put my hand in the flame for it.
(Equivalent expression in English might be that I'd not wager a lot of money on it, i.e. that I'm not completely certain given the consequences if it's wrong.)
The thing about space is, heat transfer is all radiative. The "dark" side of the probe, which is in its own shadow, faces the darkness of space (which is very cold indeed). Therefore you can put insulation on the side facing the sun, and a radiator on the dark side to remove any heat that gets through the insulation.
Pick a material for the surface of the radiator which has high emissivity.
That is, when the material gets warm, it will convert the thermal energy to electromagnetic energy (light). Some of this light will escape, leading to a cooling effect.
This is known as “incandescence” or “black body radiation”, and it’s why metals glow red hot when they’re heated to a certain temperature. (Though it’s not always red, it can be white, blue, or even UV. Animals are warm enough to glow in infrared, which is what thermal cameras detect).
> That means that while Parker Solar Probe will be traveling through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 2,500 degrees Fahrenheit (about 1,400 degrees Celsius).
I'm a little curious how they were able to determine this before even sending a craft there and measuring it and have a high degree of confidence in its accuracy.
> A NASA spacecraft has entered a previously unexplored region of the Solar System — the Sun’s outer atmosphere, or corona.
> The mission’s closest approach is scheduled for 2025 at a distance of just 6.2 million kilometres from the solar surface, well within the orbit of Mercury.
From the paper, it looks like the closest approach was
> 18.4 solar radii (R⊙ ≡ 6.95 × 10⁵ km) from the center of the Sun
Wait, what? NASA says[1] the corona extends 5 million km, so 6.2 million km would be outside the corona. 18.4 × 6.95 × 10⁵ = 12.788 million km, which is more than twice the quoted number. And according to Wikipedia[2], Mercury's orbit is ~58 million km from the sun. So it's already well within that orbit. I've had a couple beers, but I didn't think I was that drunk already. What's going on?
I'd rather have them always use both units, so that people would eventually learn intuitively, by example, what a km is relayed to a mile, or a kg to a pound, etc.
I think the 5 million km figure is just an order-of-magnitude/ballpark estimate, not something precise.
"The corona starts at 10,000 kilometers and extends out to about 10 million kilometers, where the gas finally escapes the sun's gravity and becomes part of the solar wind." [1]
I haven’t read any of this cause I’m on my phone but wouldn’t the closest approach occur in 2025? And isn’t the 6.95 quoted the closest distance so far?
I get the heat part (well, after reading the explanations in the article that is), but how do they send the data back to Earth, considering the amount of EM noise that close to the Sun?
For metric system people, if the Sun and the Earth were 1 meter apart, the probe would get as close as 11cm from the Sun.
(site writes: "If Earth was at one end of a yard-stick and the Sun on the other, Parker Solar Probe will make it to within four inches of the solar surface.")
Yes, it is. The Sun is a very large ball of gas with a small one of something that is not gas on the middle (and a gradient between them). This goes well inside the large ball of gas.
I didn't even know this was possible to get something that could withstand this much heat and still take valid measurements. This is incredible. Congratulations to the team that made this happen.
> The Parker probe crossed into the Sun’s atmosphere at 9:33 a.m. Universal Time on 28 April of this year. It took several months for mission scientists to download and analyse the data it collected, and to be sure that the spacecraft had indeed crossed the much-anticipated boundary
What an achievement this is! I can't imagine the build up and anticipation the team members endured for months on end to finally get to this point.
It’s not possible sadly. In order to crash into the sun you’d need to get out of orbit, counter-intuitively. The orbital speeds here are crazy high so the spacecraft would need either a gigantic amount of gravity assists or a gigantic rocket.
They're complementary. Parker Solar Probe (PSP) carries a smaller, less capable payload than Solar Orbiter (SO) but it goes closer to the Sun, allowing for direct sampling of the corona. PSP cannot carry cameras for observing the Sun because of how close it gets (heat shield reasons), but SO can. This allows SO to observe the Sun's corona on a large scale, while PSP can validate those measurements with local sample collection.
The NASA article on the probe mentions its autonomous course corrections abilities. Does anyone have an idea about what kind of onboard CPUs/SoCs do probes like this employ? Which ISAs? How about other hardware like memory and storage? And what kind of programming languages are used to code such internal "systems".
I'm very curious to see if someone can shed some more light on this.
>The Parker Solar Probe mission design uses repeated gravity assists at Venus to incrementally decrease its orbital perihelion to achieve a final altitude (above the surface) of approximately 8.5 solar radii, or about 6×106 km (3.7×106 mi; 0.040 au).[35] 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 near Sun radiation environment is predicted to cause 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.[34]
https://en.wikipedia.org/wiki/Parker_Solar_Probe