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Solar "Rover"

Mechanical contrivance for visiting the Sun
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The very obvious problem with sending anything to the Sun is that it would vaporise ages before it got near. Or would it?

Sunspots are cooler than the rest of the photosphere, at 3 800 K. This is, amazingly, actually below the triple (melting) point of some solid substances such as tantalum carbide and tantalum hafnium carbide, which have "melting" points of 4 150 K and 4 263 K respectively. And yes, everyone can use the internet and read Wikipedia, so no original idea yet.

The idea, then, is this: make a vehicle of some description _entirely_ out of one of these substances, so it's entirely mechanical, possibly a clockwork ornithopter with initially furled wings. Get as close to the sun as you can get with a conventional spacecraft, then fire the clockwork ornithopter at great speed towards a sunspot, possibly encased in a large block of frozen hydrogen. When it approaches the surface of the sun, decelerate it with a solar sail consisting of a very thin polished tungsten membrane, which will of course vaporise. The ornithopter then flies across the sunspot.

There are a few issues with this:

This device would have to be entirely mechanical. That needn't be an enormous problem as such because clearly mechanical computers are possible. However, it is a little hard to imagine how it could be powered owing to the fact that this substance is neither a conductor nor ferromagnetic, and is also very brittle, so there's no way it could be clockwork as a spring is unfeasible. Nor can it be rocket-propelled because any rocket fuel is going to be destroyed and possibly detonate. What I do have in mind, though, is a flywheel which is set in motion before launch, which articulates with the rest of the vehicle and powers it, maybe with a cam belt like a bike chain.

I'll get back to the internal workings in a bit because another pressing issue is the temperature of the solar prominences at 20 000 K and that of the corona of a couple of million K. However, temperature is not heat. The corona is practically vacuum and the chromosphere is also pretty thin, so in fact this may not be much of an issue.

Back to the internal workings then. I envisage a flywheel powering the entire vehicle, with a cam chain and camshaft transferring the energy to the flapping wings which will fly through the plasma of the sunspot. Two pinhole cameras focus the light of the sunspot onto a "retina" which consists of a moving cylinder of the stuff concerned, thereby focussing an image consisting of vaporised and non-vaporised portions, which will "click" round producing a kind of stereoscopic cine film mounted helically on a cylinder. Thin diaphragms of metal behind "fluffy" baffles record the audio of the journey onto gramophone discs via a stylus and a thin tympanic membrane of the same substance.

Given that the photosphere is made of plasma, although I imagine it being able to fly or swim through it with a kind of flapping motion, for all I know this is actually impossible because plasma is not gas or liquid, although it is a fluid.

The escape velocity of the sun at the surface of the photosphere is over 600 kps, so the idea currently fails right here because unless the probe starts at that velocity this is merely an art project involving sending a useable vehicle to the sun which will do something and then vaporise. Still, it's better than nothing.

Oh, and obviously it needs to be sent at night (groan).

nineteenthly, Oct 24 2017

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       (marked-for-tagline)   

       " And yes, everyone can use the internet and read Wikipedia, so no original idea yet. "
normzone, Oct 24 2017
  

       I read this idea first thing this morning and it kept popping into my thoughts randomly all day. (+)   

       How much density can plasma have?
If your ornithopter was small enough you should be able to use wing-tilt alone to deflect enough photons to escape the gravity well.
Would fullerene withstand the temperature of the suns' corona? If so would your moving parts be able to then conduct electricity?
  

       Cool idea.   

       Presumably the outer rind of the sun is at very low density, since it's the very tippety top of the sun's atmosphere. If so, then conductive heat gain will be quite slow and, just as you can stand in a sauna at 110°C, a suitable probe might well survive for quite a long time.
MaxwellBuchanan, Oct 25 2017
  

       Can't we bury a probe inside a reasonably large comet that is going to hit the sun?
theircompetitor, Oct 25 2017
  

       Since the Sun is a ball of hot gas, and its visible surface ("photosphere") represents a particular layer of gas (perhaps equivalent to Earthly cloud-tops), there is nothing upon which something might "land" and rove about. You should think of your rover as needing to be a flying machine, with appropriate wings.   

       There is still the problem of the Sun having a "surface" gravity of about 28 times Earth-normal. What is the density of the Solar atmosphere just above the photosphere layer? That's the most important fact relevant to designing (if possible at all) workable wings.
Vernon, Oct 25 2017
  

       I like [tc]’s approach. Find some sacrificial ball of ice and let it get as close as it can as long as it can hold out til everything burns up. That way you can send data back that’s useful.
RayfordSteele, Oct 25 2017
  

       First thing that comes to mind is Lexx, an insect spacecraft that could harvest a star's energy, but that could just be a Canadian rehash of Blake's 7.
bigsleep, Oct 25 2017
  

       //bury a probe inside a reasonably large comet//
// I like [tc]’s approach//
  

       Ditto. An ablative lens drilled straight through the core and use the off-gassing of the comets death to aid escape velocity.   

       Cheap and messy. Win win.   

       What information is there on the sun to send back? I doubt the sun has any information at all. Even if it were to send back one bit, or return or not return a bit of information, what would it inform you of?
Ian Tindale, Oct 25 2017
  

       ^ Information ? who cares ? We could be the species that created and released a flock of sun-divers into our star, purely for aesthetics.   

       Paradoxically, the coolest thing ever.   

       ----   

       Could you create a magnetic field to harvest energy from the fractional-c ions scurrying past ?   

       ... said energy mostly used to protect the actual physical part of the craft... that contains the bit that makes the magnetic fields that harvest the energy.   

       sorta like using a helicopter to generate electricity by tossing it on top of a geyser.
FlyingToaster, Oct 25 2017
  

       There's a Mr Desiato on the other line.   

       //there is nothing upon which something might "land" and rove about// - another, larger rover?
pertinax, Oct 25 2017
  

       To wander and rove the immeasurable beauty of the delicate flicks of Sol's plasmic touches.
wjt, Oct 25 2017
  

       Well, set the controls for the heart of the Sun then I suppose.
nineteenthly, Oct 26 2017
  

       The photosphere is apparently about one half-millionth the density of water, so in fact I'm not sure it can be flown in. I also imagine that the mechanics of plasma are significantly unlike liquid or gas. I think this probably implies an enormous wingspan and a mechanical bird which can dive as far into the sunspot as practical in order to find a denser but still cool layer.   

       I also wonder if plasma is in fact the solution rather than the problem, in that the craft could use plasma in various ways, e.g. as "wiring" and propulsion.
nineteenthly, Oct 26 2017
  

       Mirror balloon ?   

       Huge spherical mirror, very thin. Lightweight spacecraft within.   

       Balloon's density calculated to float in photosphere due to radiation pressure plus gas pressure.
8th of 7, Oct 26 2017
  

       To get data back from the mechanical probe, you could use mechanically actuated radar reflectors such as have been proposed recently (a few months before you posted this idea, I think) for a mechanical Venus rover.
notexactly, Feb 06 2018
  
      
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