Is it true there has never been a rendezvous conducted with a cryogenic stage? By any space program? Ever?
There was a NASA plan that used Delta IV heavy's stage to push a spacecraft that was docked at the ISS to l1. It would aerobreak back to the ISS or be picked up by the shuttle.
Quote from: sdsds on 06/12/2011 04:29 amIs it true there has never been a rendezvous conducted with a cryogenic stage? By any space program? Ever?They have with emptied ones I know of.
Only LOX/LH2 stages have enough performance margin on the difficult Earth - Moon segment (3 km/s to Earth escape, 4 km/s to low lunar orbit, with GEO and/or libration points between the two).
Quote from: Archibald on 06/12/2011 06:08 amOnly LOX/LH2 stages have enough performance margin on the difficult Earth - Moon segment (3 km/s to Earth escape, 4 km/s to low lunar orbit, with GEO and/or libration points between the two). I don't think I agree with that as an absolute statement. A storable propellant stage could perform a trans-lunar insertion burn just as well as a cryogenic propellant stage. It would require more propellant mass [...]
TRL for cryo storage is too low without extensive development work.ISS is built for specific and low load paths. A bunch of RL-10s would tear it apart.
http://history.nasa.gov/DPT/Architectures/Moon%20-%20L1-Moon%20Exploration%20Architecture%20DPT%20Jun_00.pdfHere is the link.
Quote from: edkyle99 on 06/13/2011 09:40 pmQuote from: Archibald on 06/12/2011 06:08 amOnly LOX/LH2 stages have enough performance margin on the difficult Earth - Moon segment (3 km/s to Earth escape, 4 km/s to low lunar orbit, with GEO and/or libration points between the two). I don't think I agree with that as an absolute statement. A storable propellant stage could perform a trans-lunar insertion burn just as well as a cryogenic propellant stage. It would require more propellant mass [...]If the results shown in the attached chart are correct, there's a surprisingly easy to remember sequence of (approximated) payload capabilities. This uses simplistic dry mass assumptions, with delta-v numbers for getting to the lunar surface from ESAS: TLI = 3140 m/s Lunar = 855 + 1911 (LOI + Descent) = 2766 m/sFor a cargo spacecraft using hydrolox propulsion for all in-space maneuvers, an ESAS CaLV launcher could put 20 mT on the lunar surface. For a spacecraft using hypergolic propulsion for all in-space maneuvers, the same launcher puts 10 mT on the surface. The mix-and-match approach of hydrolox TLI and hypergolic lunar propulsion yields 15 mT.10 / 15 / 20. Curiously easy to remember!
Quote from: Archibald on 06/12/2011 06:08 amOnly LOX/LH2 stages have enough performance margin on the difficult Earth - Moon segment (3 km/s to Earth escape, 4 km/s to low lunar orbit, with GEO and/or libration points between the two). I don't think I agree with that as an absolute statement. A storable propellant stage could perform a trans-lunar insertion burn just as well as a cryogenic propellant stage. It would require more propellant mass, but without boiloff the upmass to LEO difference would not be as large as might be expected. The difference could be further reduced by using a small cryo stage, launched at the last minute, as an augment to the storable stage.No need for ISS in either case. - Ed Kyle
We suppose an international company. That company buy bulks of cryogenic third stages from countries willing to sell them The company evidently also buy a rocket ride to loft these stages into low earth orbit. Evidently no payload is carried; no GEO satellite.
Meanwhile, lunar heavy payloads (15- 20 tons) are launched and dock to the ISS.
The company provide the cryogenic stages with Soyuzautomated rendezvous and docking gear (Kurs + probe-and-drogue). Then a booster loft the cryogenic third stage near the ISS no fly zone, the payload disengage from the space station, dock to the stage, fire, head to L1 / L2 / LLO. This a mere expension of CSI Soyuz/ block D scheme that involve the ISS into a lunar flight. By using the ISS for a lunar program, we don't have to wait 2028 and the end of its useful life to return beyond LEO... Thoughts ?
Getting your hands on Kurs for the cryogenic upper stage will cost more money than you could ever imagine.
Your architecture seems to make lunar missions more expensive, but for no obvious benefit other than "involving ISS".
Danderman, Points noted. Doesn't the ATV use Kurs ?
QuoteGetting your hands on Kurs for the cryogenic upper stage will cost more money than you could ever imagine. Can you detail more ? I'm curious...