Surviving Near The Sun Via Jump Drive...

[Spacescifi]

 

If a starship had a jump drive that made them exit 5 light seconds from the sun, could the vessel survive if it had a constant 1g-5g acceleration drive?

What about 15 or 30 light seconds if 5 is no chance?

Could a stainless steel hull work? Or would concrete be ideal? We are NOT limited by weight or material for this post, so I don't care what your hull is so long we manufacture it now in large quantities.

 

Thoughts and solutions?

 

Edited October 10, 2019 by Spacescifi

[Rakaydos]

14 hours ago, Spacescifi said:

 

If a starship had a jump drive that made them exit 5 light seconds from the sun, could the vessel survive if it had a constant 1g-5g acceleration drive?

What about 15 or 30 light seconds if 5 is no chance?

Could a stainless steel hull work? Or would concrete be ideal? We are NOT limited by weight or material for this post, so I don't care what your hull is so long we manufacture it now in large quantities.

 

Thoughts and solutions?

 

I'm presuming that you emerge with zero relative velocity to the sun. If it's an interstellar jump, there's a decent chance you're already in orbit if absolute momentum is conserved.

How long do you need to survive for?

Edited October 11, 2019 by Rakaydos

[RCgothic]

The sun has a radius of about 2.3 light seconds, so it depends a little on whether you're talking distance from the centre or distance from the surface.

5 light seconds from the centre is 2.7 light seconds from the surface for instance.

Simplistically, intensity follows an inverse square relationship with distance. Earth is about 8 light minutes from the sun, so 2.7 light seconds is 178 times closer or 31.7 thousand times more intense.

This is complicated by the sun no longer being a point source at that distance, so it could well be a great deal more.

I could just about imagine a spacecraft with a well designed insulated great shield surviving that.

However.

At 5 light seconds from the centre of the sun the force on every kg is approx 59N, or 6g. So a 1-5g spaceship wouldn't survive for long regardless of its heat shield.

[YNM]

16 hours ago, Spacescifi said:

5 light seconds ?

What about 15 or 30 light seconds ?

5 ls : ~1,500,000 km, we'll settle that with 2 solar radii.

15 ls would be 6 solar radii. 30 ls would be 12 solar radii.

Parker Solar Probe will approach down to 9 solar radii.

See also : tungsten countertop.

[kerbiloid]

Is the ship transparent?

[VincentS]

The ship would have 3 problems to solve : withstanding heat, radiations, and escape.

On the first point, my instinct is that ablative or regenerative cooling could do the trick, if mass is not a problem. If the ship is a cargo ship, cargo may be sacrificed as improvised insulation buffer. You would be losing mass fast, but that could help your TWR...

I have no idea on the second point

Escaping sun gravitation could be done in at least 3 different ways :
- If you have TWR >> 1 and your engine can endure sun radiations and heat, burn away from the sun to the closest safe spot (far enough, or Mercury shadow, whichever you can reach first at full thrust). You could probably generate a big magnetic field to use as an improvised magnetic sail, this close to the sun there should be plenty of fast charged particles...
- If you have to protect your engine from the sun, you obviously cannot turn your back on the sun, so you have to rise your apogee continuously by burning at 90° from the sun and spiral out
- Even if you have TWR <=1,  you may not be toast already (pun intended) : you could dive (almost) toward the sun and burn continuously prograde, with the lowest perigee you dare to attempt. You may gain enough kinetic energy to increase your apogee enough to be safe. Plus burning close to the sun would be highly effective due to Oberth effect. If you survive. This would obviously be the Kerbal way...

[Spacescifi]

7 hours ago, Rakaydos said:

I'm presuming that you emerge with zero relative velocity to the sun. If it's an interstellar jump, there's a decent chance you're already in orbit if absolute momentum is conserved.

How long do you need to survive for?

 

Not zero relative velocity. Let's say moon orbital velocity, since the ship just left a moon like ours lightyears away and jumped near our star.

 

It's a starpoint jump drive, making ship's jump near stars and travel through the solar system from there.

[Rakaydos]

4 minutes ago, Spacescifi said:

 

Not zero relative velocity. Let's say moon orbital velocity, since the ship just left a moon like ours lightyears away and jumped near our star.

 

It's a starpoint jump drive, making ship's jump near stars and travel through the solar system from there.

The problem with that, is that the two stars don't orbit the milky way at the same speed+direction. Maintain absolute momentum, and all that difference will catapult you at astronomical speeds.

[Spacescifi]

21 minutes ago, Rakaydos said:

The problem with that, is that the two stars don't orbit the milky way at the same speed+direction. Maintain absolute momentum, and all that difference will catapult you at astronomical speeds.

 

I know. Therein lies the challenge.

Possible solution: Use telescopes to estimate speed and trajectory before you jump lightseconds from the surface of the sun. Then accelerate to a proper trajectory so you do not go headed directly for the sun.

 

Would that work?

EDIT: Are you saying that an autoshift trajectory/speed to star jump drive would be safer?

Only up to a certain range, since another poster already pointed out that a few lightseconds from the sun is 6g. And most of the stuff we make cannot handle that without breaking. Plus you would need at keast 7g to escape unless you did the kerbal way of an orbital slingshot.

Edited October 11, 2019 by Spacescifi

[RCgothic]

Actually we can handle 6g of freefall just fine because everything is accelerating together the different parts of the ship aren't under relative strain. 

If you jumped in at orbital velocity you could break free at 1g of propulsive acceleration in the prograde direction just fine.

The point was more that a ship with only 5g acceleration available would be in a great deal of trouble if it jumped in at zero relative velocity next to a star with a local gravity of 6g.

Edited October 11, 2019 by RCgothic