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Comment by cinquemb | Hacker News Reader

I never said how easy it would be only that there is a difference between a payload that is launched via a laser and a payload that has laser capabilities in it (yes, 'moving with the projectile', like i was talking about from the beginning where you assumed otherwise).

But for one, the energy source would have to be on board the payload to power the laser (localized around the payload), and for the other (that I was not talking about) the laser is not on the payload and as the payload travels further away from the launch site, you would use an non linear increasing amount of energy and follow the path of the payload (ionizing air not only around the payload continuously but along the path where the payload no longer is, which would require more energy than needed).

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Try to read my comment, I never 'assumed otherwise', the difficulty of having the laser as payload is exactly my point.

> so I guess even for $2000 you won’t be able to have a 30 km altitude,

Does seem like it references some difficultly-ness

> flying object with perfectly controlled laser launched from a trebuchet

Does seem like it 'assumes otherwise' to (or its at least ambiguous to me and would be less so if there was a perhaps some separation between the laser and launched, but maybe that's a bit nit picky)

> The laser in the study is moving with the projectile,

And would be even more difficult than such (at least going by how much energy would be required).

But regardless, I'm not sure that 30 km altitude and first achieving mach 5 is a major constraint beyond that is probably not achievable at the $2000 price point (or its not clear to me that it is from the paper) and would be something that could be worked around with more iterations of what level of ionization of surrounding air around a projectile with a given density would give the desired amount of drag reduction (perhaps zeptosecond[0] pulses would work even better than femtosecond ones that were compared against nanosecond, or achieve similar results with lower mach number and higher density of air being ionized around the payload).

[0] https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.11...

Also try to read my other comment, the difficulty is precisely my point.

I don't see how 'laser in the study is moving with the projectile' is in any way, form, or shape ambiguous.

And the $2000 price point is not from the paper but from your own post.

> flying object with perfectly controlled laser launched from a trebuchet

Is what I considered to be ambiguous because it wasn't clear to me that you were assuming the system would be either 'laser launched' or 'launched by a from a trebuchet' with the laser part only applying to the object, regardless of your mention of:

> The laser in the study is moving with the projectile,

Your comments after that made it clear that we are both on the same page regarding the laser part is referring to the payload.

The difficulty being your point is not that interesting to me when i made the post, but the possibility of being able to send something into LEO while minimizing drag effects on the payload to something negligible along the flight path of the payload.

The $2000 came from the cost of the trebuchet system, I'm more interested in at what price point would a system be possible (Ideally below the cost of hypersonic missiles [0] now that I assume use something like this) with a rail gun kind of system.

[0] https://www.scmp.com/news/china/science/article/3142581/chin...

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