back to article FYI NASA just lobbed its Parker probe around the Sun in closest flyby yet: A nerve-racking 15M miles from the surface

NASA’s Parker Solar Probe has kept its cool, successfully surviving sweltering temperatures to reach its first close encounter with the Sun, coming within 15 million miles of the solar surface. Launched in August, the spacecraft is on a mission to study the star at the center of our Solar System. The goal is to help scientists …

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Talk about the gates of Hell !

I really wonder how many of those flybys the probe will actually survive - I'm guessing it won't be functional all the way through more than 20.

Then again, given NASA's history of generally working much longer than planned, this may become another plucky one in which case, how many more flybys could it accomplish ?

EDIT : looks like there won't be a chance to get plucky, apparently the number of flybys is fixed and not extensible. So the Parker probe will become another piece of human history sailing out forever. At great speed.

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Re: Talk about the gates of Hell !

How many more? Depends. Is it spiraling inwards? What kind of fuel reserves does it have?

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Mushroom

Re: Talk about the gates of Hell !

Is it spiraling inwards? No, it's ellipsing inwards with the help of Venus!

https://en.wikipedia.org/wiki/File:Animation_of_Parker_Solar_Probe_trajectory.webm

FWIW, it's not just a case of "setting the controls for the heart of the Sun". You need a lot of delta-v.

https://space.stackexchange.com/questions/13396/do-any-current-icbms-have-the-delta-v-to-target-the-sun

p.s. Careful with that axe, Eugene Parker. IGMC.

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Happy

Re: Talk about the gates of Hell !

It's got a British made back-up mode - so that it can last a bit longer, if the kit holds out better than expected. It can deploy the emergency heat shield, which is a knotted handerkchief, and has a small reserve of San Miguel for when it runs out of fuel.

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JDX
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Re: Talk about the gates of Hell !

So is the number of fly-bys fuel-limited even if everything works?

I wonder if it's set to just drive straight into the sun if all goes well? Or maybe they are 100% sure it will burn up/fail in one of the last orbits and 20 is already several more than it could realistically achieve.

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Pint

Re: Talk about the gates of Hell !

The article mentions getting repeated gravity assists from Venus. Rich Purnell probably designed the orbits so that a small amount of fuel delta-V used near perihelion triggers a larger drop of delta-V due to the Venus flyby.

Really smart way of doing it if you ask me so Rich gets a pint.

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Pint

Re: Talk about the gates of Hell !

very complex differential equations are probably involved, yeah. Too much math for me. Basically your acceleration due to gravity is changing in a non-linear manner the entire time, and you can't make assumptions about it being constant at any point, really (not and get THAT CLOSE to the sun without missing the mark). And as you approach Venus, the gravity source changes, and you have to consider Sun + Venus and Sun - Venus and changing fuel mass, all vector summed and compensated for by distance from the center of mass of each involved 'thing'. yuck.

A beer, at the very least, is deserved. Well done indeed!

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Re: Talk about the gates of Hell !

Sounds like you know your Astronomy...Domine

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Coat

Re: Talk about the gates of Hell !

@Not Spartacus

Is the British based backup tea based?

Could it be an attempt to make a really fresh, *hot* cup of tea as a source of Brownian motion?

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Scorchio

Well done team!

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Cool!

Well, not really, but you know what I mean.

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5.3 degrees of sun

Angular size that is: if my skoolboi trig is right then that's about eleven times the width of the full moon seen from Earth, or about the size of the top of a demitasse cup held at arm's length. Quite something to see through the world's thickest welding mask...

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Re: 5.3 degrees of sun

I would have approached it differently. From Earth the Moon is the same angular size as the Sun.

The Earth is approximately 90 million miles from the Sun so at the current 15 million miles the probe is 6 time closer so the Sun would appear 6 times bigger. At closest approach at 3.9 million miles, say 4 to make the maths easy then it is 22.5 times closer. So maybe you have a factor of two missing somewhere.

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@Graham Newton - nice approximation

To my surprise it gets all the way to 9.5 degrees (5 million miles from the sun) before it becomes even 1% different to the trig result.

My dumbass result: error is close to 1.6 so maybe I mixed miles and km when grabbing figures from google. Time to order a Royale with Cheese...

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Brilliant stuff!

In more ways than one. Hats off (mine is the grey Tilley today) to the entire team at NASA.

The sun is rather quiet now, but hopefully the Parker probe will be able to study the sun as it reaches maximum in 6 years or so. As an avid amateur solar astronomer, I will be following this mission closely (but at a safe physical distance).

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Re: Brilliant stuff!

"as it reaches maximum in 6 years or so"

Unless we're at the beginning of a prolonged period of minimal sunspot activity, as some suggest is probable.

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Alien

Re: Brilliant stuff!

That'll never happen. Wait...

https://en.wikipedia.org/wiki/Maunder_Minimum

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Trollface

Why don't they use multiphasic shields?

It worked for Voyager to enter a star's corona and stay there for hours!

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Glad they got there OK

I was worried they were going the wrong way when they launched it at night.

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Paris Hilton

Re: Glad they got there OK

I was worried they were going the wrong way when they launched it at night.

If they had really sent Parker to the sun at night then couldn't they have done away with all that heavy heat shield mass?

.

.

.

I will forever regret not using that question at a Q&A with a representative of the ESA's Solar Orbiter team.

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5-4-3-2-1

"Parker, Well done."

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Re: 5-4-3-2-1

We might as well mention the 'real' Parker I suppose.

https://en.wikipedia.org/wiki/Eugene_Parker

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Re: 5-4-3-2-1

Yes Milady.

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Re: 5-4-3-2-1

heh obligatory 'Thunderbirds are GO!"

I thought of 'that episode' I remember from when I was a kid, when Thunderbird 3 had to go rescue a 'Sun Probe' with people on it. That was the 1960's when I last saw it. U.S. stations played the Thunderbirds TV shows. It was AWESOME. And, sadly, Thunderbird 3 didn't get enough screen time...

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Happy

Re: 5-4-3-2-1

I loved that. They had a thing for rescues when things were supposedly getting hotter and hotter. So sprayed water onto the puppets so they looked like they were sweating.

My favourite is where some people are trapped in the vault of the Bank of England. Running out of air of course, and so "sweating" as the heat builds up. Parker admits his criminal past a safe-cracker and borrows Lady Penelope's hair pin, and picks the lock.

I'm hoping the real Bank of England vaults are slightly less badly designed... Happy days!

Thunderbird 4 was my favourite. But only because it was yellow.

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Boffin

So what I'm wondering now...

As the probe ellipses inwards, so to speak, it accelerates etc.

But is velocity still a Constant in these circumstances?

I need to know this urgently.

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Devil

Re: So what I'm wondering now...

The answer to this question is relative

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Re: So what I'm wondering now...

But is velocity still a Constant in these circumstances?

No. As you noted, the probe accelerates (changing speed and heading of the velocity vector). From this plot of Parker's course, you can see how the time intervals change with position. It takes longer to cover the same distance when further from the sun - Parker slows down. Another plot also shows distance (in solar radii) and time, with zoomed in section of the closest approach.

And as noted in the font of all human knowledge, Parker is barely puttering along at Venus (26km/s) but accelerates to 120km/s near the sun.

So, in short: Parker moves much faster at periapsis (the close point to the sun) than at apoapsis (furthest point).

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Re: So what I'm wondering now...

No - speed is increasing as it 'falls' to perihelion, and then slowing as it climbs to aphelion.

Velocity is both speed and direction, the speed is changing, and the direction is changing as well.

What is constant (ignoring drag/radiation pressure/any thruster based control input) is the energy.

Continuously trading gravitational potential energy back and forth with kinetic energy.

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Re: So what I'm wondering now...

I should probably add that there is also some (repeated) trade of energy with Venus - gravity assist.

Whilst the probe arrives and leaves the gravitational well of Venus at the same speed, its direction is changed (hence the new orbital path each time) - and that direction change is a velocity change, which requires energy - which is exchanged with Venus.

So Venus does change orbital velocity, but its mass is such that the change in velocity is negligible.

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Re: So what I'm wondering now...

> "But is velocity still a Constant in these circumstances?"

Averaged across the entire orbit, yes. Some of that total velocity does get transferred to Venus tho, in order to shorten the orbital period and do more science faster. The Venus passes also help to sharpen the ellipse, which gets the spacecraft closer to the Sun without needing lots of delta-v. The elongated orbit also lets the probe communicate between passes, and limits the time spent close to the Sun, reducing wear and tear.

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Time warp

Did it go back in time and come back with whales?

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Happy

Re: Time warp

No. But it did do a jump to the left.

Before taking a step to the right...

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Burning question

How long does it take to flash roast a sheep in a vacuum at that distance from the sun?

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Re: Burning question

At that distance from the Sun, the sheep would be cindered on the outside before the middle was cooked, because flesh is a poor conductor of heat, so I don't think that flinging sheep at the Sun would ever result in any uniform state of ROAST = 1.

You could apply a heat shield to the sheep, but that seems to defeat the point of your question.

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Flame

Re: Burning question

You don't want to flash roast it. You want to slowly cook it on a spit using wood fire ( embers ) not the charcoal briquettes. Occasionally using some green wood from a fruit tree ( plum is best) to provide extra flavor. 7 hours minimum on the heat. The soluble fats slowly dripping out of the meat to

This best done with an esky full of ice cold beer, and give the spit a quarter turn after each beer. Drink slowly, otherwise the missus will find you passed out in the back yard and the lamb burnt, whilst she was slaving away in the kitchen making the roast vegetables, salads and setting up. Good times, Apparently.

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That's cool ... I mean hot

Its a hot cool ride ...even

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Joke

> The shield has a diameter of 2.3 meters and is 11.4 centimeters thick.

What’s that in feet and inches?

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Trollface

The shield has a diameter of 91 inches and is 0.37 feet thick.

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Anonymous Coward

Simple solution

If they went at night they wouldn't have a problems with getting hot..... - sorry old joke.

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Go

Do it again, but harder!

Project Lyra: A feasibility study for a mission to the interstellar asteroid ‘Oumuamua

For the first option, we use a mission concept that has been previously proposed by a Keck Institute for Space Studies report for exploring the interstellar medium. It is essentially a rollercoaster ride The spacecraft is first sent on a trajectory out of the Earth’s gravitational field using a large rocket, for example the Falcon Heavy, Space Launch System, or the Big Falcon Rocket. The spacecraft is accelerated to such high velocities that it is not only thrown out of the Earth’s gravity field but has enough energy to fly out to Jupiter. At Jupiter, the planet’s gravity decelerates the spacecraft with respect to the Sun. ... our spacecraft has been decelerated so much by exploiting Jupiter’s gravity field that it is now on a trajectory that it is falling towards the Sun in an almost straight line, an extreme roller coaster ride, although it takes over a year to fall. Of course the spacecraft will not fall into the Sun but would move away from the Sun once it has passed its closest point to the Sun. The spacecraft gets very close to the Sun, about 3 solar radii or about 1.5 million km. At such a distance, the solar radiation is about 20,000 times higher than what you receive during a sunny day. Converted to Watts per square meters, the power per area is about 15 MW / m². This is higher than the power per area inside a fusion reactor. To avoid that the spacecraft melts away, a heat shield is used which is similar to the heat shield of the NASA Solar Orbiter mission, which fill fly close to similar distances to the Sun and is currently undergoing testing. Now, at the closest point to the Sun, the spacecraft ignites a solid propellant engine it has been carrying all its way. In orbital mechanics, you get the biggest “bang for the buck” for a rocket engine, if you ignite it at the closest point to the central body. Hence, the whole idea of falling so closely to the Sun is to ignite the engine at the closest point of approach and then to be propelled away from the Sun with the maximum “bang”. The spacecraft flies away from the Sun at the incredible speed of about 370 km/s. At this speed you would get from London to New York in 15 seconds. Note that this is the speed you would need for a mission duration to ‘Oumaumua in 8 years and a launch in 2021. The spacecraft will have a velocity at infinity of 55 km/s and is therefore much faster than ‘Oumuamua with 26 km/s. The spacecraft would fly pass ‘Oumuamua in 2029, taking images using a telescope at a distance from the Sun of 69 Astronomical Units (Earth-Sun distances). At this point ‘Oumaumua will be a black object in front of the blackness of space. Where the human eye would fail, a telescope and other instruments will suck in the electromagnetic waves that are nevertheless emitted by ‘Oumuamua. The data will then be sent back to Earth with an antenna powered by nuclear radioisotopic generators, a chunk of Plutonium whose heat is transformed into electricity. Finally, the data is transformed into images. What will we see?

The Lyra paper is Project Lyra: Sending a Spacecraft to 1I/'Oumuamua (former A/2017 U1), the Interstellar Asteroid, Andreas M Hein, Nikolaos Perakis, Kelvin F Long, Adam Crowl, Marshall Eubanks, Robert G Kennedy III, Richard Osborne arxiv.org/abs/1711.03155

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Re: Do it again, but harder!

The 2001 - 2003 era plan for Solar Probe included a perihelion pass (over one of the solar equator) at 2 solar radii (~ 1.5 million km) above the solar surface and somewhat more distant passes over each solar rotation pole (N and S). No one in the science community believed the spacecraft would survive until the second polar passage.

It's worth noting that toward the end of its planned lifetime, PSP will be orbiting at ever greater inclinations to the ecliptic. The hope is to obtain measurements at up to ~ 30° N and S of the ecliptic.

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Anonymous Coward

..am I the only one who noticed..

..that its traveling at 1/3600 (ish) the speed of light.

Only 3599/3600's to go.

For you celestial mechanics bods out there - how much angular momentum from a sympathetic planet would it have to pick up before it went some reasonable fraction of the speed of light?

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Re: ..am I the only one who noticed..

It would need linear momentum - and alot of it...

And a very significant number of assists, as you go faster past a body you get less time to be deflected, so the increase in energy is reduced.

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Angel

My first thought was for Roger Waters.

Set the controls for the heart of the sun

The heart of the sun, the heart of the sun ...

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Alien

Are ‘Disaster Area’ playing a gig anywhere nearby?

Disaster Area was a plutonium rock band from the Gagrakacka Mind Zones and was generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all. Regular concert goers judged that the best sound balance was usually to be heard from within large concrete bunkers some thirty-seven miles away from the stage, whilst the musicians themselves played their instruments by remote control from within a heavily insulated spaceship which stayed in orbit around the planet - or more frequently around a completely different planet.

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Units

Please use sensible units as the primary unit for temperature. Farenheit is a quaint archaism that should be in a museum. Also when converting please pay attention to the significant figures. Quoting the temperature to one degree accuracy, four significant figures, is ludicrous.

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Re: Units

Farenheit is NOT an anachronism.

That silly French / Continental stuff is unwanted here.

The English, the English, the English are best, I wouldn't give tuppence for all of the rest.

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FAIL

Re: Units @Fizzle

In which case you should be using Kelvin old bean.

Herr(e) Farenheit wasn't English you know :-)

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Re: Units

Farenheit is NOT an anachronism.

It's "Fahrenheit".

FAHR-EN-HEIT.

To be pronounced with a German accent.

Chappy.

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