81–90 of 105 posts
This is the major reason why asteroids are in total much more important than the moon or even Mars.
Earlier quoted context omitted.
Wouldn't your idea, at best, null-out the forward propulsive force, but not actually decelerate the ship?
Not my idea - it's been around for decades. It works because you can treat the two kites as one system, because they're both connected to the ship.
> It works because you can treat the two kites as one system, because they're both connected to the ship.
Care to supply some citations?
Very light on details
Yep, that is wired for you. As far as I can tell, this plan was first proposed in the '80s. The technical challenges of a 1.21 jiggawat laser, and a gigantic sail have led to it never being attempted even though it is probably theoretically feasible.
Earlier quoted context omitted.
Another thing to consider: mirrors are never perfect. 100% of the light is not reflected. If the spaceship uses high quality laser mirror with 0.00001% absorption rate, absorption from 5.8 terawatts is still 5.8 megawatts of power to get rid of in space.
Nit: 0.00001% of 5.8 TW is 580 kW. (I assume you just misplaced a decimal point.)
5,800,000,000,000 W × 0.00001 =
58,000,000 W = 58 MW
Earlier quoted context omitted.
In the story "Flight of the Dragonfly", which used the same propulsion system, they simply detached a portion of the sail, and used it to reflect the beam back at the spacecraft to decelerate it.
This doesn't make sense to me. The detached portion would be subject to radiation pressure from the ground-based propulsion lasers, and would quickly be pushed away from the spacecraft it was meant to act on.
You'd still have to account for the light coming from the source as well as from the daughter sail, but a black coating on the back of the spacecraft's reflector would take care of that; it would give you n force pushing you away from the original light source, and 2n pushing you towards the source.
The coordination and planning required for such a device would not be trivial, but it would be possible.
As much as I love the idea, it is fairly impractical for the reasons that other commentors have noted. Call me greedy, but within the constraints of a balanced budget, I would like to see an increased portion dedicated to science (be it a 'cancer moonshot' or an actual marsshot) vs social programs ... maybe we could find some real solutions to these issues. In my own life I have a tendency to skimp on the 'now' in th…
Note that this basically happened already. As Apollo wound down, the War on Cancer wound up https://en.wikipedia.org/wiki/War_on_Cancer
Turns out it's far more difficult to cure cancer than to reach the moon.
Earlier quoted context omitted.
Not my idea - it's been around for decades. It works because you can treat the two kites as one system, because they're both connected to the ship.
> Not my idea - it's been around for decades. > It works because you can treat the two kites as one system, because they're both connected to the ship. Care to supply some citations?
https://en.wikipedia.org/wiki/Solar_sail#Interstellar_flight