5 ms·

It would be nice if they could use solar wind to decelerate as they approached. I know there's not enough energy there to insert them into an orbit, but they mi

It would be nice if they could use solar wind to decelerate as they approached. I know there's not enough energy there to insert them into an orbit, but they might get time for a few more pictures?

1812Overture 11y ago
Just flip the battery in the laser around and it will pull instead of pushing.
- LyndsySimon 11y ago
  You mean we should... reverse the polarity?
  - rotexo 11y ago
    excuse me, but I think you forgot to take the opportunity provided by that ellipsis to put on your visor.
david-given 11y ago
You can --- you use a thing called a magsail. The short version is: remember the old Bussard ramscoop idea? You use a magnetic field to collect interstellar hydrogen which you then fuse for thrust? Turns out that in our part of the galaxy, you get more drag from the sail than you do from the fusion thrust, so the idea was scrapped. An embarrassingly long time later people finally realised that they'd invented a fuelless brake, and the idea was resurrected (but without the fusion drive). The maths are quite plausible and the sail itself trivially simple --- just a wire loop. http://www.centauri-dreams.org/?p=22138 http://www.centauri-dreams.org/?p=22138 However, I don't think they'd be compatible with this idea --- I suspect you wouldn't get one big enough to be useful in a one gram package. But estimating the numbers is beyond me. Here's the paper if you want it. http://www.niac.usra.edu/files/studies/final_report/320Zubrin.pdf http://www.niac.usra.edu/files/studies/final_report/320Zubri...
- mrfusion 11y ago
  Very fascinating! I had no idea we had such a viable option for braking. Two questions for you if you're up for it. Could we use this concept for braking during earth re entry to depend less on complex heat shields? Why is the idea of a bussard ramscoop not viable?
maverick_iceman 11y ago
Why decelerate? At 0.2c it takes around 40 minutes to cross 1AU. (Ignoring time dilation which is not super significant at 0.2c.) That gives ample time to take photos from a moderate distance.

It would be nice if they could use solar wind to decelerate as they approached. I know there's not enough energy there to insert them into an orbit, but they might get time for a few more pictures?

1812Overture 11y ago

Just flip the battery in the laser around and it will pull instead of pushing.

LyndsySimon 11y ago
You mean we should... reverse the polarity?
- rotexo 11y ago
  excuse me, but I think you forgot to take the opportunity provided by that ellipsis to put on your visor.

david-given 11y ago

You can --- you use a thing called a magsail. The short version is: remember the old Bussard ramscoop idea? You use a magnetic field to collect interstellar hydrogen which you then fuse for thrust? Turns out that in our part of the galaxy, you get more drag from the sail than you do from the fusion thrust, so the idea was scrapped. An embarrassingly long time later people finally realised that they'd invented a fuelless brake, and the idea was resurrected (but without the fusion drive). The maths are quite plausible and the sail itself trivially simple --- just a wire loop. http://www.centauri-dreams.org/?p=22138 http://www.centauri-dreams.org/?p=22138 However, I don't think they'd be compatible with this idea --- I suspect you wouldn't get one big enough to be useful in a one gram package. But estimating the numbers is beyond me. Here's the paper if you want it. http://www.niac.usra.edu/files/studies/final_report/320Zubrin.pdf http://www.niac.usra.edu/files/studies/final_report/320Zubri...

mrfusion 11y ago
Very fascinating! I had no idea we had such a viable option for braking. Two questions for you if you're up for it. Could we use this concept for braking during earth re entry to depend less on complex heat shields? Why is the idea of a bussard ramscoop not viable?

maverick_iceman 11y ago

Why decelerate? At 0.2c it takes around 40 minutes to cross 1AU. (Ignoring time dilation which is not super significant at 0.2c.) That gives ample time to take photos from a moderate distance.