Quote from: Danderman on 04/01/2015 03:42 pmQuote from: JasonAW3 on 04/01/2015 03:22 pmActually, you might want to recheck that. the original idea for an otv was published before we even had space stations. Von Baun and a number of other Nasa types had been thinking about it back before they eve3n launched men into space.The classical paradigm used the tug to lift payloads from the station to the Moon or a higher orbit, and used a Shuttle to get payloads to the station.What Lockheed is proposing is to use a rocket to lift a payload to a parking orbit, using the rocket upper stage to stabilize the cargo payload, send a tug from the space station to rendezvous with the upper stage, and then return to the station with the tug. Von Braun never considered that architecture.Another approach Back in the Day was to have a "Shuttle" or Apollo type vehicle carry a Resource Module launched together with the crewed vehicle, and use the crewed vehicle to carry the cargo module to a station. That was considered and rejected for SkyLab.As an aside, one of the benefits of operating a space station is that it provokes new thinking about operations in space. The more the station is used, the more operational alternates emerge from station requirements. Von Braun lived in a world where there was no station, so he could not see all the requirements.And that's the key. Getting something into space now is, comparably, not a big problem.It's manipulating what's been sent there to where you want it to be that's the trick, unless I missed something in my infantile skills in orbital mechanics.And thrusters only go so far, unless all those robot arms on the Shuttle Orbiter and ISS are completely optional.A number of us watch the SpaceX floating pad. It has its own power, but it needs guidance to move to the right positions with precision. (So does the cruise ship cam we use to watch the pad when it's moored.)The Jupiter isn't so much as a spacecraft as it is a Elsbeth III or the Go Quest support ships that move the cargo to storage and transfer points. This action doesn't require the ISS but supports its mission, as it would others.Several Jupiters could form a "dock" of its own, holding canisters for any number of needs that can be transferred elsewhere, sitting in a nice parking orbit.As I might have said before, this is an infrastructure device. All the freight trucks in the world would be useless without cranes, tugs, forklifts, and this seems a very good start to defining space freight hardware. STS was supposed to work this way but was obviously far too expensive and compromised by design and politics.
Quote from: JasonAW3 on 04/01/2015 03:22 pmActually, you might want to recheck that. the original idea for an otv was published before we even had space stations. Von Baun and a number of other Nasa types had been thinking about it back before they eve3n launched men into space.The classical paradigm used the tug to lift payloads from the station to the Moon or a higher orbit, and used a Shuttle to get payloads to the station.What Lockheed is proposing is to use a rocket to lift a payload to a parking orbit, using the rocket upper stage to stabilize the cargo payload, send a tug from the space station to rendezvous with the upper stage, and then return to the station with the tug. Von Braun never considered that architecture.Another approach Back in the Day was to have a "Shuttle" or Apollo type vehicle carry a Resource Module launched together with the crewed vehicle, and use the crewed vehicle to carry the cargo module to a station. That was considered and rejected for SkyLab.As an aside, one of the benefits of operating a space station is that it provokes new thinking about operations in space. The more the station is used, the more operational alternates emerge from station requirements. Von Braun lived in a world where there was no station, so he could not see all the requirements.
Actually, you might want to recheck that. the original idea for an otv was published before we even had space stations. Von Baun and a number of other Nasa types had been thinking about it back before they eve3n launched men into space.
Historical reference, LM has suggested similar before:http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740023215.pdfRandy
Think we have been down this road before with Space Systems/Loral's COTS II proposal, again a tug architecture using an existing spacecraft bus:https://web.archive.org/web/20110718101724/http://www.constellationservices.com/SSL_COTS_Fact_Sheet_Dec_2007.pdfThe proposal was eliminated in the first round of the COTS II proposal for many reasons, but included “operational complexity of the Space Tug system” http://forum.nasaspaceflight.com/index.php?topic=12822.0The Lockheed proposal will run up into the same issue, except it will compete with two finished competitors and one past CDR, so while interesting it wont get picked for CRS-2.
Three points:1. Just because two different proposals share the same broad architecture doesn't mean they are either both picked or both rejected. If the details are different, the selection board may like one better than the other. You allude to this in your post when you say the SS/Loral proposal was eliminated "for many reasons", not just because of the perceived complexity of the tug operations.2. It's not the same people making the decision for CRS 2 that made the COTS 2 decisions. Opinions can differ.3. The situation is different now. At the time of COTS 2, there was no existing system and NASA had to fund development, so it could only choose two awardees and had to minimize risk to try to make sure it got at least one working system. Now, there are two existing systems that already work, so NASA can be freer to experiment with riskier options. If the riskier options fail, NASA is out nothing because in CRS 2 they only pay for operational missions and as long as they have other awardees, they can just give more missions to the other options if the tug option doesn't pan out.
Quote from: Ronsmytheiii on 04/29/2015 12:34 amThink we have been down this road before with Space Systems/Loral's COTS II proposal, again a tug architecture using an existing spacecraft bus:https://web.archive.org/web/20110718101724/http://www.constellationservices.com/SSL_COTS_Fact_Sheet_Dec_2007.pdfThe proposal was eliminated in the first round of the COTS II proposal for many reasons, but included “operational complexity of the Space Tug system” http://forum.nasaspaceflight.com/index.php?topic=12822.0The Lockheed proposal will run up into the same issue, except it will compete with two finished competitors and one past CDR, so while interesting it wont get picked for CRS-2.It should be noted that CSI was a partner in the Loral proposal in COTS II, as well as a prime in COTS I, and that Lockheed was a partner with CSI in COTS 1. CSI came up with the intermodal architecture, which NASA didn't like the first two times around, but maybe they will come around on it this time.Not wanting to blow my own horn, I was the guy who came up with the concept way back when. I look at the complex issue the way that some people for LOR - it was much more complex than the standard direct approach to lunar landing where everything went to the surface of the Moon, but LOR was much more efficient. A tug based ISS resupply system is similarly more complex, but more efficient.
Letting the politics aside, could an idle Jupiter have been deployed to salvage yesterday's failed progress launch?
Nothing on Progress for the arm to grab onto; typically end effectors have specialized grapple fixtures.The better question is what Jupiter would do with a dead Progress, if it could grapple Progress somehow.
