Tether Transport

>
> To all members,
>
> In studying Boeings proposed HASTOL system I cannot see the point of
> utilising a hyper-sonic aircraft to bring the payload into a position from
> which a tether can capture it and deliver it to orbit. Would it not be
> cheaper to utilise a mass driver to deliver this payload. This would also

It would be cheaper still to use single stage sounding rockets.
Mass driver does not work well in atmosphere, and required large
development cost. Sounding rockets are already available with little or
no development cost.

> mean that the tether tip would not have to travel at hyper-sonic speeds in
> the upper atmosphere. In fact the end point of the tether would move mainly
> up and down in the atmosphere like a lunavator, but only down to about 100
> kilometres altitude. The payload would have some downrange velocity but only
> enough to ensure it did not hit land in the case of failure.
>

Yes, we want the payload at tether tip to stay above the atmosphere,
hence the attraction of a sounding rocket. Launching a payload by this
method allows the rocket to carry about 50 times as much as if it were
trying to inject the payload into orbit by itself.

> I propose that SSI or some other organisation put a mass driver on the
> western slopes of Mt Kilimanjaro in Tanzania. This mountain is only 19,500
> feet above sea level but has the advantage that it sits on the equatorial

This method has a couple of major problems:

1) a large rpoportion of the vleocity would be lost due to air
resistance

2) the payload would be heated to a very high temperature by air
resistance

3) large capital cost

4) very high acceleraiton precludes delicate cargos, e.g. animals and
humans. Most spacecraft built today could not handle that level of
G-load.