I think the idea is very interesting, but please correct me if I’m wrong, isn’t the payload experiencing a sustained acceleration of hundreds of thousands of Gs, if not millions?
I am not sure that anything useful could survive that kind of sustained crushing acceleration. By comparison a rifle bullet being shot is around 100k Gs for millisecond , this would go on for weeks or months.
ben_w · 46m ago
Given how short the proposal's tethers are, I'd suggest one can very easily reduce the peak G-force for any given linear speed by making the tethers longer. Once they get to the physical extremes (especially the bit at the end about enhancing tensile strength with an electric charge, which I suspect will involve surface voltages sufficient for pair production from any stray electrons accelerated from one to the other*), it stops being easy.
It's SpinLaunch from solar orbit rather than the surface of the Earth (in fact, they themselves say so at the end of 11.1). Even for the current tech demo of SpinLaunch, that was getting 10k G and the company found it wasn't too difficult to make payloads survive that: https://www.youtube.com/watch?v=g-DjBHroA1I
Yes, that's 10x-100x less than what you're asking (I've only skim-read the paper, your 100k-1M is certainly plausible given what they're focusing on is the "can it be done at all" and not a detailed launch proposal), but in practice if we were limited to 10k (we're probably not) that only means making the tether 10x-100x the length in this paper.
* My citation here is just "gut feeling" as I play around with ideas like this from time to time, and this particular thing, using electric forces for a non-gravitational orbit, was something I came up with and then rejected on this basis as part a hard-science tractor beam in the novel I've still not finished writing, and the accidental antimatter problem happened with relatively small accelerations for a plausible mass probe.
bad_username · 4h ago
The white paper says the payload release doesn't have to be precisely timed, if TARS is on a circular orbit, and I do not understand why. Sure, the plane in which the payload shoots off, is defined by the orbital position of TARS. But there are 360 degrees of freedom within that plane. If we aim at e.g. a specific star, how is release timing not a critical factor? And if it is, what timer would survive the solar radiation and extreme spinning, remaining reliably operational and microsecond accurate?
progval · 1h ago
Are you talking about this?
> In the case where TARS is on a circular orbit, the moment of release need not be precisely when v = v_targ, but rather can be at a specific orbital phase position instead.
My understanding is that it means it does not have to be precisely timed with regard to velocity, but has to be with regard to angle.
echelon · 12h ago
David Kipping of Cool Worlds Lab just uploaded a video about TARS:
This is amazing. How have i never seen this channel before?
mperham · 8h ago
He’s an incredible scientist and educator. His back catalog of videos is well worth watching.
idiotsecant · 8h ago
He wrote the paper too :) Anyhow, I wonder if you can make a useful probe in the payload of a few grams? Maybe a swarm of them could act in concert to do useful things?
I am not sure that anything useful could survive that kind of sustained crushing acceleration. By comparison a rifle bullet being shot is around 100k Gs for millisecond , this would go on for weeks or months.
It's SpinLaunch from solar orbit rather than the surface of the Earth (in fact, they themselves say so at the end of 11.1). Even for the current tech demo of SpinLaunch, that was getting 10k G and the company found it wasn't too difficult to make payloads survive that: https://www.youtube.com/watch?v=g-DjBHroA1I
Yes, that's 10x-100x less than what you're asking (I've only skim-read the paper, your 100k-1M is certainly plausible given what they're focusing on is the "can it be done at all" and not a detailed launch proposal), but in practice if we were limited to 10k (we're probably not) that only means making the tether 10x-100x the length in this paper.
* My citation here is just "gut feeling" as I play around with ideas like this from time to time, and this particular thing, using electric forces for a non-gravitational orbit, was something I came up with and then rejected on this basis as part a hard-science tractor beam in the novel I've still not finished writing, and the accidental antimatter problem happened with relatively small accelerations for a plausible mass probe.
> In the case where TARS is on a circular orbit, the moment of release need not be precisely when v = v_targ, but rather can be at a specific orbital phase position instead.
My understanding is that it means it does not have to be precisely timed with regard to velocity, but has to be with regard to angle.
https://www.youtube.com/watch?v=MDM1COWJ2Hc