SE/ATO Hybred

Hey all! I'm new to this forum and just learned about ATOs from JP's post on the Liftport forums. I had an idea for a modified DSS and would like to hear your thoughts.

If the Edwards SE concept were modified to service a DSS at 30km, you could achieve about 1 ton of payload for about every 2 tons of cable. I believe a DSS would capable of holding up this mass since JP has said that he plans ascenders with 15 ton payloads. The HALE system (being developed by Liftport) would be capable of resupplying helium to the DSS more efficiently than an Ascender since climbers would be able to traverse the cable in a matter of minutes. The cable would make the DSS more accessable for people since it wouldn't be reliant on weather conditions and flight times. The Ascenders have larger payloads, so they would be still be used for cargo transport. The cable could also be reeled up to the DSS and be used as an anchor at various port locations.

I think Liftport and JP Aeronautics would benefit from each other. Liftport needs high altitude platforms to test their tethers and JP Aeronautics would benefit from HALE. I don't work for either company, but I'd still like to see someone succeed with cheap space access.

I have a question regarding the airship. Assuming that it uses ion engines, how will it get through the radiation belt in a reasonable amount of time? A rotovator may be the best way for an ion propelled craft to accelerate. Would the airship be able to withsand the g-forces of a rotovator? (about 5 gees depending on length)

hat problems might be caused by the circumstance that the DSS is said to be floating in a current? May be that the tensions the nanocarbontubes would have to withstand are less than the limitations of the nantubes.

In at least one other thread I already thought about a DSS to be one part of a space elevator - as a by-station and/or as the first point to fix the cable during installation coming down from geostationary orbit or above it. I am not sure but I seem to remember that the thoughts included an Ascender-like climber.

So I find your idea intteresting.



Dipl.-Volkswirt (bdvb) Augustin (POlitical Economist)

The most pessimistic projections for the tensile strength of macroscale CNT is about 35 GPa. Even with that as the upper limit, CNT would have a greater strength-to-weight ratio than any other known material (kevlar is about 5 GPa). For a DSS anchor, the limiting factor would be the weight of cable supported by the DSS (a fraction of the DSS's lift capability). There are two options to address excessive tension: larger anchor cables and longer anchor cables. Larger anchor cables would be the prefered solution since it is necessary to have the cable under steady tension for a climber to ascend. This brings up another point: the DSS would need to be as stable as possible, having minimum altitude fluctuation.

Another application of CNT would be the construction of Ascender and DSS envelopes. A greater strength-to-weigh ratio material would make higher altitudes possible, lowering the demands of ion acceleration.

What does GPa stand for?

GPa is a unit of pressure equal to a billion newtons per square meter. 1 GPa is approximately 10000atm, or about three times the breaking strength of mild steel. The most extreme steel wire today has a fibre strength of about 5GPa and is available in only small quantities, this strength is comparable with only a few other fibres. I don't think 35GPa is the lowest concievable attainable estimate of bulk nanotubes, but I think it's a fairly reasonable figure for what might be available in less than three decades.

I suppose GPa is short for Giga-Pascal - is that right?



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

Yes, that might have been a better answer

For a 30 km cable to DSS, you wouldn't need CNT cables. Kevlar or even high tension steel would suffice.

An airship/kite would stay entrained within upper currents so that suspended turbines could capture the wind, as the envelop is covered with solar panels and kite webbing as well. Thus power form many sources is available. If this can also be a rectenna for in atmo power beaming, so much the better.