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Not really relevant but, if we we had an arbitrarily super fast spacecraft, how would we prevent it from hitting a small rock and exploding?
Maybe they we will be able to detect a marble from hundreds of thousands of miles in the empty space with new radar/lidar tech.
Not really relevant but, if we we had an arbitrarily super fast spacecraft, how would we prevent it from hitting a small rock and exploding?
Not really relevant but, if we we had an arbitrarily super fast spacecraft, how would we prevent it from hitting a small rock and exploding?
Ultimately, you can't. Space is really, really, really big and empty, though. Unimaginably so, which would make an incident be some really bad luck. In something like the lightsails, you'd just launch multiple simultaneously. Space is so big and empty that even for something like the asteroid belt you could pass through any point randomly and on average be thousands of kilometers from the nearest rock. Perhaps even t…
It's extremely unlikely to get close to any object while randomly passing through its orbit.
Unfortunately, space becomes a lot smaller once you want to park yourself in a similar orbit to another object. Don't get me wrong, it's still massive, but since orbits trace out a path the problem becomes figuring out if two paths intercept rather than if two points intercept.
This is why access to 'space' will not really be impacted in the case of a Kessler cascade; you can go through low earth orbits on the way to somewhere else, but if you tried to stay in low earth orbit you'd almost certainly be hit by something.
Can someone more familiar with orbital mechanics help me understand why it looks like the perigree is coming down in opposite to the apogee? I'm but a mere KSP player, but I've always thought the perigee comes down in a fairly linear fashion based on drag, which is mostly a function of altitude - I would assume they'd be using the sail to just "burn prograde" whenever the solar angle is possible, raising both the apo…
(another ksp'er here...) I think the problem is atmospheric drag, which increases when the sail is open. If you're looking to increase apogee, the most efficient place to do so is at the perigee, which also happens to be where the atmospheric drag is the worst. So setting the mission, you get to choose the orientation of the sun relative to your orbital ellipse. If the sun direction to the sun is perpendicular to the…
My understanding of what's going on here is that the light sail isn't aiming or changing at all. It's just a big sail, in orbit. When it's moving away from the sun, the sail is being pushed "forward", which adds to it's velocity- this increases the apogee on the opposite side of the orbit. When it's moving towards the sun, the sail is being pushed "backwards", lowering it's current velocity and reducing the perigee.…
Earlier quoted context omitted.
It does work though, depending on the material your sail is made of. Try it: attach an electric fan to a pinewood derby car and point it so it is blowing into a tin foil sail also attached to the pine wood derby car. The car will move forward.
An electric fan on a derby car works the same way a propeller does though right? You don’t need the sail at all. It works by pushing against the surrounding medium. This seems different than a laser in a vacuum.
Not really. If a fan was able to blow air in a vacuum it would produce thrust as well. Basically a rocket does that. It's just blowing gasses out the back.
It's Newton's law of motion, "every action has an equal and opposite reaction".
Not really relevant but, if we we had an arbitrarily super fast spacecraft, how would we prevent it from hitting a small rock and exploding?
Why would it explode? More likely, the small rock would put a hole into the spaceship. This isn't a disaster. The spaceship residents would notice a gradually decreasing amount of pressure, assess where the leak is, and put a piece of duct tape over the hole. Remember kids, real life isn't like the movies.
My understanding of what's going on here is that the light sail isn't aiming or changing at all. It's just a big sail, in orbit. When it's moving away from the sun, the sail is being pushed "forward", which adds to it's velocity- this increases the apogee on the opposite side of the orbit. When it's moving towards the sun, the sail is being pushed "backwards", lowering it's current velocity and reducing the perigee.…
I think LightSail 2 already does just that, though, but possibly not very efficiently.
From the article:
> LightSail 2's single momentum wheel, which rotates the spacecraft broadside and then edge-on to the Sun each orbit to turn the thrust from solar sailing on and off.
Can someone more familiar with orbital mechanics help me understand why it looks like the perigree is coming down in opposite to the apogee? I'm but a mere KSP player, but I've always thought the perigee comes down in a fairly linear fashion based on drag, which is mostly a function of altitude - I would assume they'd be using the sail to just "burn prograde" whenever the solar angle is possible, raising both the apo…
I'd guess the sail orientation is not changing relative to the sun, so at perigee this provides an acceleration (because it's mostly in the velocity direction), which raises apogee. At apogee it provides deceleration (because it's in the anti-velocity direction), which lowers perigee. There are also probably other effects depending on the sail orientation that muck with the inclination and other elements. It's a litt…
> One such refinement involves LightSail 2's single momentum wheel, which rotates the spacecraft broadside and then edge-on to the Sun each orbit to turn the thrust from solar sailing on and off.