It has been suggested before, using lasers as a means of propulsion (and a sail) but it required a set-up of the laser and a docking system where it was intended to land to put on the brakes. This was a concept that offered great hope but lacked the final solution. However, this too shall pass!
Actually if it works, which there is no reason the propulsion part won’t, there is a place for it and maybe a way to work it out! First let’s deal with if no braking system is worked out.
Thanks to advancements in technology especially as it relates to directed energy, this is no pipe-dream or impossibility. AND even more exciting is that the ‘laser photon driver’ can theoretically any mass system where the final speed is only dependent on the scale of the driver built. BUT if no way to slow down &/or stop the space craft is figured out then we can only do a fly-by of Mars in 3 days, make it to Alpha Centauri and tons of other places in the galaxy with speed as well but we can’t slow down to pay a visit.
If you recall the system previously conceived about 8 years ago (by a professor at Washington University) needed the landing station to be placed in advance of a ‘flight’ to any location and so the thought was go the old fashioned and slow way to Mars the first trip and while there set up the braking system (which consisted of a laser system that would slow it down by pushing against – reversing the forward motion using the same method that sent it forward.)What if instead of stopping, the propulsion is utilized to circle Mars and while slow down a second ‘pod’ or group of mini-spacecraft could separate and land, piece the braking system together then when it is done, the larger ship lands on Mars.
CONSIDER THIS: A basic assumption – the propulsion comes in the form of a laser on Earth puts some interesting limits on it when it comes to interstellar travel or does it? Unless the Earth can provide lasers all around its circumference then there is going to be a time in its regular orbit that the laser will go ‘dark’. Conversely, how long is the laser actually needed? There comes a point where it doesn’t produce more energy as the ‘spacecraft’ is maintaining a constant velocity on its own (as long as it doesn’t run into anything...)so perhaps that isn’t actually a problem. It might become one though further out in the galaxy when the laser is no longer providing propulsion and while it was cruising at .25 the speed of light something may have caused it to slow down or stop. Home becomes a long way off at that point! How do you get the energy to return? Of course a massive satellite system could be arranged that could provide continuous energy in the form of the lasers. There is always a way – it is more a matter of is that way at a cost that is doable?
The paper prepared by Philip Lubin (current developer and designer) offers much to consider however doesn’t give the full picture as to what has been done in the lab thus far and what still remains to be done. Still, the idea was a good one when offered the previous two times so the only thing lacking with this offering is a braking method.
Is braking that important?