The Moon Could Be Our Source Of Highspeed Space Travel

[Spacescifi]

 

Ignoring the cost, it is physically possible. Physics does not say no.

Step 1: Build a magnetic railway or coil-tube on the moon that goes ALL THE WAY AROUND the moon's equator.

Step 2; Fly spacecraft to lunar mag launch system. Let them inside.

Step 3: Use magnetism to accelerate spacecraft to higher and higher speeds as they can essentially orbit...on the surface of the moon due to the mag-tube. Reaching speeds that would take ridiculous amounts of propellant otherwise.

 

4.  At various points the tube can tilt up so that spacecraft are shot out along popular travel trajectories.

5. Obviously replicate the track on EVERY airless moon in the solar system. Get speed and trajectory for no propellant cost other than reaching the magnetic transport tube.

 

Result: Lots of traffic between airless moons. In between worlds rockets could do what is necessary to enter orbits and land.

 

Your tboughts?

I think this is actually...at least by physics, feasible.

 

You could even ramp a vessel all the way up to relativistic speec and shoot it to the next system.

 

Slowing down would be a problem though.  

Space is big, so the bigger your transport system, the more efficient it is, especially when it is reusuable too!

Edited May 30, 2021 by Spacescifi

[FleshJeb]

40 minutes ago, Spacescifi said:

relativistic

The radius of the Moon is 1737 km. The speed of light is 300,000 km/s. The equation for centripetal acceleration is a=v^2/r

Solve for the centripetal acceleration necessary to hold a circular orbit at 10% lightspeed. (You may subtract 0.00162km/s^2 to account for the Moon's gravity.)

Divide total by 0.00981 km/s to get G-force.

Also, read:

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

http://www.projectrho.com/public_html/rocket/enginelist.php#massdriver

Have fun doing math: http://www.projectrho.com/public_html/rocket/images/mission/deadfrog42.png

More realistic idea:

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

[Spacescifi]

11 hours ago, FleshJeb said:

The radius of the Moon is 1737 km. The speed of light is 300,000 km/s. The equation for centripetal acceleration is a=v^2/r

Solve for the centripetal acceleration necessary to hold a circular orbit at 10% lightspeed. (You may subtract 0.00162km/s^2 to account for the Moon's gravity.)

Divide total by 0.00981 km/s to get G-force.

Also, read:

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

http://www.projectrho.com/public_html/rocket/enginelist.php#massdriver

Have fun doing math: http://www.projectrho.com/public_html/rocket/images/mission/deadfrog42.png

More realistic idea:

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

 

Why could'nt it work?

Magnetic could be used to keep the ships on track I think....unless you're saying ships will fly off once they get too fast ...magnets won't be able to control them?

 

Is that what you're saying?

[Piscator]

The problem seems to be that the non-magnetic cargo and/or passengers would be squashed flat.

[Spacescifi]

14 minutes ago, Piscator said:

The problem seems to be that the non-magnetic cargo and/or passengers would be squashed flat.

 

Gradual acceleration of 1g over time.

 

Unless you are saying centripetalforce gravity would get them the faster they circled the moon.

 

So that would be their max speed, whatever circle the moon circling speed that is so high that if you go any higher the centriptal force will kill you?

What speed is that? Just curious?

Even so, cargo vessels without passengers could withstand more...but only so much.

Edited May 30, 2021 by Spacescifi

[Vanamonde]

You wouldn't need a ramp up at the end. If you got something going that fast all you'd need to do is make sure it didn't smack into a hillside after emerging from the launcher. 

[Shpaget]

9 minutes ago, Spacescifi said:

What speed is that? Just curious?

Why don't you do the calculation yourself? Everything you need is in FlashJebs post.

[Spacescifi]

4 minutes ago, Vanamonde said:

You wouldn't need a ramp up at the end. If you got something going that fast all you'd need to do is make sure it didn't smack into a hillside after emerging from the launcher. 

True....that was what I was trying to avoid by using a ramp.

 

Ramp is just to clear exiting spacecraft away from the transport tube expeditiously. 

Because at such high speeds, even grazing the lunar surface before clearing the moon on a slingshot trajectory could be fatal.

[Vanamonde]

Just now, Spacescifi said:

True....that was what I was trying to avoid by using a ramp.

 

Ramp is just to clear exiting spacecraft away from the transport tube expeditiously. 

Because at such high speeds, even grazing the lunar surface before clearing the moon on a slingshot trajectory could be fatal.

At such high speeds, a sudden turn is going to smoosh your ship. 

[Spacescifi]

8 minutes ago, Vanamonde said:

At such high speeds, a sudden turn is going to smoosh your ship. 

 

I see.

 

So just clear out the hills beforehand.

 

Wonder if anyone has made the OP in kerbal?

Would be a nice proof of concept.

 

EDIT:The tube should have open parts where the vessel could use rocketry to propel clear of the railway before it hits the next tube enclosure.

Edited May 30, 2021 by Spacescifi

[FleshJeb]

1 hour ago, Spacescifi said:

Unless you are saying centripetalforce gravity would get them the faster they circled the moon.

If I read the dV chart right, it takes 5.71 km/s to get to Jupiter from the Moon with Hohmann transfer (lowest possible energy).

a_cent = v^2 / r = 5.71 km/s * 5.71 km/s / 1737 km = 0.0187 km/s^2

a_cent_net = a_cent - a_grav = 0.0187 km/s^2 - 0.00162 km/s^2 = 0.0172 km/s ^2

g = a_cent_net / g_earth = 0.0172 km/s^2 / 0.00981 km/s^2 = 1.75 g, just to hold the craft down to the Moon.

Since you're accelerating along the track at 1 g, and that's perpendicular to the centripetal acceleration, we use Pythagoras.

g_total = sqrt(1.75^2 + 1.00^2) = 2.02 g, is what the craft experiences just before it leaves the loop. That's not bad. However, I know from reading Larry Niven's notes on Ringworld, that you can model it as a suspension bridge. Essentially, you'd have to build a bridge TWICE as strong as one on Earth, all the way around the Moon. Also it's upside-down, and loaded with very large superconducting magnets.

I drove over this last week, it's HUGE:

Spoiler

That's just to get to Jupiter, the nearer of the two gas giants.

10% lightspeed = 30,000 km/s (compared to 5.71 km/s).

Even if you could find materials strong enough for your spacecraft, magnets, and bridge (you can't), you'd rip apart the Moon.

Hopefully that helps you envision some sense of scale.

Edited May 30, 2021 by FleshJeb

[kerbiloid]

11 hours ago, Spacescifi said:

Wonder if anyone has made the OP in kerbal?

KSP has rails?

Spoiler

  

10 hours ago, FleshJeb said:

I drove over this last week, it's HUGE:

I saw it in Cloverfield. It's SMALL.

(Though, maybe not exactly this one, of course, but looking similar.)

 

Btw 5.75 km is something about the sound speed in the ramp metal...

A liquid ramp.