NASA's Newest Spacecraft Will Fly Through the Sun's Scorching Hot Atmosphere (theverge.com) 96
In T-minus three days, NASA will launch a car-sized spacecraft to investigate our Sun's scorching hot atmosphere. "The vehicle is the Parker Solar Probe, and it's set to launch at 3:33AM ET on Saturday, August 11th, from Cape Canaveral, Florida. "It'll be riding on a Delta IV Heavy rocket made by the United Launch Alliance, which will send the probe zooming toward the inner Solar System," reports The Verge. "Just six weeks after launch, Parker will do a flyby of Venus to alter its route slightly, and then six weeks later, the vehicle will be in the corona. Over the course of seven years, Parker will do 24 orbits around the star, as well as six more Venus flybys so that it can get even closer to the Sun's surface over time." From the report: NASA has long wanted to send a vehicle to the Sun's atmosphere, but such a mission has been considered impossible until the last few decades. This region of space, known as the corona, is filled with tiny, energetic particles that can reach above 3 million degrees Fahrenheit. Any vehicle that ventures near this region must have sophisticated protection to keep from melting. But thanks to advancements in carbon manufacturing and other key areas of engineering, NASA has been able to create a vehicle with a state-of-the-art heat shield and other crucial cooling systems. The result: the spacecraft will stay at room temperature in some of the hottest places in the Solar System.
The Sun's corona is actually 300 times hotter than the surface of the Sun, and no one understands why. The region gets so hot that chunks of the corona actually accelerate and break away from the immense pull of the Sun at supersonic speeds. These so-called solar winds shoot highly energized particles out in all directions, which then slam into surrounding planets. Parker is tasked with investigating the mechanics of the breakaway effect and why the atmosphere is so much hotter than its source.
The Sun's corona is actually 300 times hotter than the surface of the Sun, and no one understands why. The region gets so hot that chunks of the corona actually accelerate and break away from the immense pull of the Sun at supersonic speeds. These so-called solar winds shoot highly energized particles out in all directions, which then slam into surrounding planets. Parker is tasked with investigating the mechanics of the breakaway effect and why the atmosphere is so much hotter than its source.
OB (Score:4, Funny)
Nothing hard about that. Let's see them do it during the day.
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3:33 Really? Like the mason 33 level or something .....
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They need metaphasic shielding for that.
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Such a pity they called it "Parker".
Was "Icarus" already taken?
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Such a pity they called it "Parker". Was "Icarus" already taken?
From TFA:
Eugene Parker published a new theory about how stars release energy. He predicted that the atmospheres of stars like our Sun get so hot that they are continually flowing outward, bathing all the planets around them in particles. Parker came up with the term “solar wind” to describe this phenomenon.
He's also done a whole lot with magnetic fields and astrophysics in general: https://en.wikipedia.org/wiki/... [wikipedia.org]
So, we can name it after an extremely successful astrophysicist, or after a rather-not-so-successful ancient greek kid :)
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Re:Delta IV (Score:5, Interesting)
Because it's been planned for YEARS.
You don't build a satellite, then get the lowest bidder. You have to figure out where you want the spacecraft, then which launch vehicles are powerful enough to get something around the weight you estimate into the proper place. Then you have all of the fiddly bits to make sure it's small enough and light enough so you can still reach the right orbit.
(disclaimer: I used to work for the Solar Data Analysis Center)
STEREO's launch was almost delayed (even further than it already was because of the strike + spy satellites cutting in line) because they had to swap to a heavier battery for the self destruct of the second stage ... JPL managed to find an alternate orbit that they could achieve with the extra weight that would still let the mission have a chance at accomplishing its goals.
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Car-sized? (Score:3, Funny)
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How can they use that many words yet manage to say absolutely nothing?
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Um...
This region of space, known as the corona, is filled with tiny, energetic particles that can reach above 3 million degrees Fahrenheit.
Which for the rest of the world, translates as "above 1.5 million degrees Celsius".
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The article pretty much focuses on the temperatures. If you want to know about how close it gets, you should check out this new fangled thing called the internet.
It will approach to within 8.86 solar radii (6.2 million kilometers or 3.85 million miles) from the "surface" (photosphere) of the Sun and will travel, at closest approach, as much as 700,000 km/h (430,000 mph). [wikipedia.org]
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You haven't read reports on when a solar event or something similar is going to happen, have you? Literally everything about the event will be discussed EXCEPT the actual time to look for said event.
Generally it's something like, "On Friday, look to the southwest. .
It's amazing how this one bit of information is repeatedly left out. Many times the web page for
Is That Fast? (Score:4, Interesting)
chunks of the corona actually accelerate and break away from the immense pull of the Sun at supersonic speeds.
What's the speed of sound at the surface of the Sun, compared to sea level on Earth?
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Re:Is That Fast? (Score:4, Interesting)
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Re:Is That Fast? (Score:4, Informative)
I am guessing this is just part of the poor quality in science reporting. Because they don't want to use the international standard of speeds of American Foot Ball Fields per second.
While I guess they are talking about speeds of a few thousands kph which would seem fast in terrestrial terms. However in astronomy terms it is rather slow.
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Between 8000 and 9600 meters/second. But there is so much turbulence and magnetic field flux that it is like wanting to know the speed of sound inside a fireball.
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There is so much turbulence inside a fireball with volumes of gas expanding and compressing faster than sound waves can travel across them. However, with the Sun, there are sound waves that travel across the interior:
https://www.livescience.com/62... [livescience.com]
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Yeah, it's a pet hate of mine - talking about x-times the speed of sound in the upper atmosphere. At -90 C in the Mesosphere the speed of sound is 271 m/s - 80% of that at sea level (ISA).
I know that they actually mean x-times 340 m/s, and at high multiples the effects are nigh-on meaningless, but when Felix Baumgartner made his jump the ambiguity was that he achieved Mach 1.25 (t=-50 C, a=300 m/s, v=1357 km/h), but using the above assumption you'd think he achieved 1,530 km/h.
I'm looking forward to a pedan
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chunks of the corona actually accelerate and break away from the immense pull of the Sun at supersonic speeds.
What's the speed of sound at the surface of the Sun, compared to sea level on Earth?
Probably doesn't matter. So long as the corona hits you before you hear it breaking away, it's super sonic. Although really, this is outer space, so they should have used the prefix of hyper- instead.
What i want to know (Score:1)
is that if they can keep a satellite at room temperature whilst dipping itself in the corona of the sun, why is aircon complicated, unreliable and expensive?
Re: What i want to know (Score:3)
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Because heat and tempereature are two different things. I bet the corona is an extremly thin gas. Meaning that even though it is crazy hot, there is very little energy in it per volume. Temperature is the average speed (i.e energy) of molecules in a substance. While heat is the total energy. So even though the corona is a few million degrees celcius, a cubic meter of it might contain way less heat (energy) than one cubic meter of pleasantly body warm pool water.
To keep cool you need to move heat from one pl
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I bet the corona is an extremly thin gas.
Plasma, not gas. Density is a trillionth that of the solar surface, which itself is a trillionth the density of water. So yeah, I guess you might call it thin.
Calculating ... a volume of corona the size of the Earth might weigh on the order of a kilogram. (or a gram or a ton? not much anyway)
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Radiant heat from the sun will dominate, and it will be extremely high. It's 1300 W/m2 here at earth (without the atmosphere blocking some of it). Closer to the sun this will be much greater, and the sun will take up much more of the satellites sky. The surface temperature of the sun (that solar radiation is going to heat the leading skin of your spacecraft to) is almost 10,000 F or 5,500 C. This is well above the temperature that any material stays solid, so ablative heat shielding is the only option. This
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No, this isn't going through a thick atmosphere. It doesn't have to be ablative, just very high emissivity. Going through the earth's atmosphere gives compression heating and erosion, which lends itself to ablation. However, the particle flux in the corona is very low, and the energy is almost all radiative, so a reflective shield is a fine approach, and in fact is the one used.
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Aircon
You keep talking about this "aircon." Let me guess: you eat vegemite or some other ghastly substance unfit for consumption by proper English speakers... ;)
Re:What i want to know (Score:4, Interesting)
1. Size: This is a car sized device. the electronics they need to keep cool is probably a small box.
2. Lifespan: Your AC probably works well for a couple of years then become unreliable. There is no chance of us trying to get this device back. The system will work for a while and will die.
3. Environment: Water, Dirt, Dust, Bugs, Hair. will get into your AC system and muck it up. vs operating in a vacuum.
4. Cost: If you want you 12x12x8 foot room to have reliable AC you probably will need to spend millions of dollars in latest material tech to retrofit it. Or just pay a fraction of that total cost, with getting your AC Fixed every few years. I am not sure why you think a satellite cooling system is cheap?
Compared to most things standard Air Conditioning is Simple, Reliable and Cheap.
You can build one yourself with an icebox, a small pump, some metal piping (copper is probably easiest) and a room fan. You can probably fix your yourself with some quick searching. However it is probably cheaper and easier just to replace a home unit. Or replace a part.
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Aircon is expensive because you and most all other people are willing to pay that amount for it.
Radiation (Score:5, Informative)
The heat from the sun is almost entirely radiant. The only particles leaving the sun are helium atoms, which are really hot but they don't transfer a lot of heat. So, basically, you cover the probe in a whole bunch of very reflective foil and that's enough to keep the thing cool enough. If you look at the pictures, there's a big heat shield on one end (probably foil-covered ceramic) and the rest is covered in foil.
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The sun's surface is at almost 10,000 deg F. Even if you manage to reflect 99% of the incoming radiation, your reflector will not remain solid. The heat shield must be ablative.
Airconditioning won't work here. The view angle of the Sun will be at least 90 degrees. Even with a highly emissive side and a highly reflective side, your steady state temperature will be at least 3000 deg F. But I bet they aren't going to enter a circular orbit around the sun (it takes an enormous amount of thrust to slow down that
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I work at the laboratory where this spacecraft was designed and built, and I did work on the craft a very little bit. For this mission into the Sun's corona, the outside temperatures will be upwards of 1400C. The heat shield is a 11.5 cm thick carbon composite shield. It is not ablative. The shield is at a distance from much of the craft as to create a large enough umbra to contain all the components. Anything that falls outside the umbra would be cooked to a crisp. The solar arrays retract, so that when th
Do you Review your sources? (Score:3)
Carbon [wikipedia.org]
Tungsten [wikipedia.org]
Carbon Sublimation point 3915 K (3642 C, 6588 F)
Tungsten Melting point 3695 K (3422 C, 6192 F)
Carbon is a fun element, that is why we like to make materials out of it. It can be arranged in a lot of ways, plus we can mix it with a lot of other elements. Sometimes the trick isn't to absorb all the heat but transfer it somewhere else.
Re:Room Temperature? (Score:4, Interesting)
If we have the technology to keep part of it at room temperature, then we should have sent actual astronauts instead.
And I am sure you are the first to volunteer to shoot around the sun at 450,000 mph for 7 years in a craft that will most likely be sent spiraling into the Sun once the mission is complete. Oh, yeah, and because the heat shield is only on one side of the craft, any error in attitude means the craft melts and you die a horribly painful but probably pretty quick death.
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Re:WHY FARENHEIT (Score:4, Insightful)
Right, because 2 million K or C is soooooo much more accessible than 3 million F. It just means "really really hot". They are giving us one significant digit in a 7-place number.
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Moon Farmer: Yep, drops down to minus-173.
Fry: Celsius or Fahrenheit?
Moon Farmer: First one, then the other.
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Well, from now on you can't feign ignorance!
As an American (on a US website, BTW) I share your frustration, but if it's any consolation our engineering schooling requires being fluent in both sets of standards, which is a pain in the ass. Look up slugs as a unit of mass if you want to crawl out of your skin.
Re:timetravel programmed ... (Score:4, Funny)
How are they going to fit two whales inside that thing?
The same way they deal with the "Transparent aluminum" problem. "Laddie, shall I just punch up clear?"
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Not really.
Heat from many kitchen appliances is about 25% radiant, depending on the type of appliance and the amount of conduction/convection captured by any hood.
Heat from the average active office worker is about 20% to35% conduction/convection, 25% to 40% radiant, and 30% to 50% sweating (latent heat)
Heat from office equipment ranges from 10% to 40% radiant. And heat gain through a sunlight window is
Time reversal? (Score:1)
In T-minus three days, NASA will launch
If you don't understand geek talk, don't use it. T-minus three days is _now_, with T being the launch time.
Basically they are saying "Three days before launch time, NASA will launch"... Good grief.
Easier ways to burn money (Score:1)
But this is the kind of thing that inclines me to wonder if we should be ejecting our space program into the corona.
Can you imagine dying without knowing why the sun's atmosphere is hotter than its surface? You know what? I can. I am completely OK with that.
What could possibly be the answer that anyone would care about
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Here are some of the question they are hoping to get a better answer on source [vox.com]:
This is what we expect to happen with sources of heat: The farther away we are from the center of the flame, the cooler it becomes. But this doesn’t happen with the biggest, baddest fire in the solar system, our sun.
The surface of the sun is around 10,000F; its atmosphere, the corona, is around 2 million degrees, about 200 times hotter. It’s like if an airplane took off from ground level where it was 60F, and then reached a cruising altitude where it was 12,000F. It sounds preposterous. And the plane would melt.
Scientists call this weird phenomenon the “coronal heating” problem, and it has been stumping them for decades. In the early 1940s, scientists determined that one of the elements in the corona was a form of iron that had been stripped of 13 of its electrons, and it takes a massive amount of energy, in the form of heat, to pull electrons away from an atom of iron. But really, the mystery stretches back even further: When scientists first detected the iron in the 1860s, they mistook it for an entirely new element they dubbed “coronium.”
The coronal heating problem is just one of three interrelated mysteries the Parker Probe will collect data on in hopes of solving.
Another mystery is solar wind. This “wind” is composed of particles of matter being shot out from the sun’s corona in all directions. These particles get accelerated to speeds of millions of miles per hour, and no one knows exactly how. (Solar wind is why we have aurora borealis and aurora australis — the northern and southern lights — at our poles. Earth’s magnetic field deflects the wind particles to the poles, where they collide and ionize in a brilliant light show.)
Last is the mystery of coronal mass ejections. These are the sudden explosions of plasma and particles that spew from the sun and could potentially knock out power grids on Earth. We don’t completely understand the physics of these explosions; nor can we predict when and where they will happen (and if Earth will be in the crosshairs).
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People don't know why this happens. The answer could (easily) be something that will never, never help human beings.
I am betting it won't.