A common core could be designed, with common avionics and mounting fixtures for the various instruments that'd be best for that particular mission, common RCS system, common propellant tanks and systems, common computers and data storage, common communications suites, etc.
Missions vary so much in initial and late delta-v and instruments and energy and thermal needs that the end results are not obvious, but it appears unclear that SMD would see attractive cost or performance benefits from an inefficient common probe design flying on a heavy lifter.
In my opinion, the way we'll get space travel to be, well, "common", is to move away from the one off designs. The computer analogy might be sorta applicable. The common core that you mention is the MoBo, which has slots for the attachment of specialty cards. The common core may not be the most efficient in volume or mass, but in these marginal areas, these efficiencies are less paramount.But I said that in discussing this sort of comparison, it's important not to compare a crab apple with a naval orange. I'm starting to think that it is necessary to compare apple LV's and orange LV's of similar capabilities. If one can assume a $300M cost, what then are the characteristics and abilities of the LV's available at that price point? Plus, the entire spectrum of costs should be considered.
Over on another thread, the idea of launching multiple probes on an SDHLV was brought up as a possibility:
Actually most probes are based off earlier designs.
As for constellations of probes, sometimes you just don’t need battle star Galatica to get good data.
The economies-of-scale argument applies regardless of whether you launch your probes all on one vehicle or separately.
There's also the all-eggs-in-one-basket problem.
The delta IV heavy is available at that price point. It will take a Miracle for an SDHLV to get that low or an unusual ability for more than one science mission to share the same launcher. I think perhaps a 40 ton to orbit delta or atlas or perhaps its upgraded cores that is less than 500 million a launch could be useful but a 60+ ton to orbit SDHLV probably is not. An upgraded delta or atlas that can lift say 30 tons to leo could be useful for both commercial crew, commercial cargo, and if cheap enough a science mission but to be useful it is going to have to be cheap enough to be purchased by ONE science mission.
Cool, I'm glad you like the idea John. Even a blind dog finds a bone once in awhile I guess.Like I said on the other thread, you could do a multiple probe mission to the Outer planets, and send it on a similar trajectory to that of Voyager 2. (if such a window exists in the near future).
I think perhaps a 40 ton to orbit delta or atlas or perhaps its upgraded cores that is less than 500 million a launch could be useful but a 60+ ton to orbit SDHLV probably is not.
Ariane 5 was originally sized for the Hermes spaceplane. This forced Arianespace to fly double payloads to fully utilise the vehicle's fullcapacity. Fortunately the size of comsats allowed double payloads to be flown regularly to the same orbit. This worked out fine for Planck and Herschel, but if one of these had run into development problems the other would have been held up. Note that ESA did not launch two Mars Expresses or Venus Expresses on Ariane: it used Soyuz.
...not a good idea to risk tens of billions in probes just to save a couple of billions in rockets.
On the other hand, I wouldn't risk several multi-billion probes in one launch, even if the rocket seems very safe on paper. For Flagship-class probes, the launch is a small part of the budget - not a good idea to risk tens of billions in probes just to save a couple of billions in rockets.
Topic: Multiple probes on the new LVQuote from: pathfinder_01 on 09/01/2010 09:52 pmThe delta IV heavy is available at that price point. It will take a Miracle for an SDHLV to get that low or an unusual ability for more than one science mission to share the same launcher. I think perhaps a 40 ton to orbit delta or atlas or perhaps its upgraded cores that is less than 500 million a launch could be useful but a 60+ ton to orbit SDHLV probably is not. An upgraded delta or atlas that can lift say 30 tons to leo could be useful for both commercial crew, commercial cargo, and if cheap enough a science mission but to be useful it is going to have to be cheap enough to be purchased by ONE science mission.Just can't get past the "HLV's suck, love the EELV" thing, can you. What's it take for you to stay on topic?Topic of *THIS* thread: Multiple probes on the new LV. (That's the SLS SDHLV)Stay on topic.
I think you have misconstrued my views. The reason why I am so anti Shuttle derived SLS is because I am seeing unrealistic numbers as well as a search to justify its existence. Heck even I tried hard to figure a reason for it and the best I could come up with is Hubble or some sort of refuel able on orbit service craft. The senate attempting to write it into law does not look good from the “It is the best that the industry can offer” point of view. It looks like they want it this way to hell with the consequences. It isn’t that I think the EELV are better. I think they are a much better fit for the budget and if done smartly more likely to be useful to others. Every time I see a six flight right for shuttle derived, I get the feeling that someone is trying to sell me a something not good. Six flights are unrealistic on several fronts. The shuttle at most flew six times a year and usually 4-5. This means that starting off with six flights is assuming that SDHLV will fly more times per year than the shuttle or shuttle derived needs to in order to make it’s numbers. Even without commercial cargo or crew, how does one get this flight rate? The ISS would only need 3-4 flights for crew flights at most and those 3-4 flights could carry quite a bit of cargo themselves if launched via an HLV. Unlike the shuttle, Orion is not very useful in LEO So you are not likely to have non ISS LEO missions with it. You certainly don’t need heavy lift for ISS cargo. The stuff for BEO is currently not in the budget (landers, habs, earth departure stages) and with commercial crew and cargo how many flights do you need? If BEO flight were available, I could see two BEO missions a year but it is not. Now as to how this relates to probes going on HLVS. A small HLV that was cheap enough to be purchased and did not require an unrealistic flight rate to get down to $500 million could be a boon. If delta IV heavy is currently 500 million (I had seen them offer it to NASA for human launch for 300 million if they can goatee so many flights a year) then utilizing it could either enable ULA to offer the delta IV heavy itself cheaper or lessen the costs of closely related variants. An EELV of 40 tons is more likely to have more in common with the current 2ish ton one than a 100 ton monster. So long as it does not get too big it can share parts, people plants, equipment. Now I don’t know if a 40ton to orbit HLV is good for Human space flight. It could be too tiny, but I would bet it could be a boon to science because it would be affordable and could lead to lower cost for not just itself but its smaller related boosters. A shuttle derived has little chance to meet those numbers and even if it could the benefit would solely go to NASA. Now as for SLS doing multi probe missions not likely and even if you did want to do multi probe missions you don’t need heavy lift of any sort to do it. You could purchase multiple rockets and so long as the total is less than 500 million you are ahead with less risk of a single failure taking out all your probes. You could build probes like smart one and hitch a ride with a commercial satellite. The one thing SLS could do is the rare huge probe like Cassini or Galileo assuming it’s costs don’t drive even missions with budgets that big away and mission planners think the risk of using SLS is worth it(i.e. Does it under deliver like Galileo and the Shuttle. Galileo missed two windows…..). I would put SLS in the same category as Falcon 9. I would prefer Atlas or Delta for proven reliability but would be wiling to use it once I saw it regularly launched without major delay or hassle.
The reason why I am so anti Shuttle derived\SLS is because I am seeing unrealistic numbers as well as a search to justify its existence. Heck even I tried hard to figure a reason for it and the best I could come up with is Hubble or some sort of refuel able on orbit service craft. The senate attempting to write it into law does not look good from the “It is the best that the industry can offer” point of view. It looks like they want it this way to hell with the consequences...........