Author Topic: Multiple probes on the new LV  (Read 14507 times)

Offline JohnFornaro

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Multiple probes on the new LV
« on: 09/01/2010 02:35 pm »
Over on another thread, the idea of launching multiple probes on an SDHLV was brought up as a possibility:

http://forum.nasaspaceflight.com/index.php?topic=22381.msg633107#msg633107

The idea is that there could be a common probe platform on which is mounted different probe designs.  Thus, a constellation of probes could cooperatively perform various missions.

I can think of three mission types which could benefit from this approach.  Jupiter, Saturn, and the Asteroid tour.  On the latter tour, if the giant asteroid worm from Star Wars eats one of the probes, then the others could photograph it from a safe distance.  I think even Mars would benefit from having a costellation of coordinated orbiting sats probing the surface and surveying for exo-biology and landing sites, for example.  They could later double as a comsat network.  There would be a cost savings in the commonality of the probe platform, which would include, as Lobo pointed out:

Quote
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.

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.

Alexw objected saying:

Quote
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.

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.

The larger vehicle, combined with multiple probes on similar platforms, might be able to send, say, four probes to Saturn.  Each sub-mission profile would look more carefully at a subset of the moons, the rings, and the surface weather patterns, say.  The bandwidth would be four times higher, since probes could time their various orbital insertions and data transmission times.  It would open up quite a different way of going about robotic surveying missions.
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Offline pathfinder_01

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Re: Multiple probes on the new LV
« Reply #1 on: 09/01/2010 09:24 pm »


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.


Actually most probes are based off earlier designs. They are not as one off as they appear. Voyager, Cassini, and Galileo are all based off Mariner.  In fact the Voyagers were renamed voyager from mariner 11 and 12 while Cassini was originally called Mariner mark II and would have had an nearly identical probe that surveyed the asteroid belt(it was cancelled).  Magellan was built from spare parts left over from Voyager and Galileo. 

Anyway when they build a probe they try to reuse as many pervious subsystems they can and then build off of it. In addition they try to incoperate new technology into them. For instance Voyager and Galileo use tape drives while Cassini has solid state memomry. It is the mission the drives the design of the probe.
« Last Edit: 09/01/2010 09:30 pm by pathfinder_01 »

Offline pathfinder_01

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Re: Multiple probes on the new LV
« Reply #2 on: 09/01/2010 09:52 pm »
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.  As for constellations of probes, sometimes you just don’t need battle star Galatica to get good data. You and I are HSF fans and as much as we wish we can find a use for an HLV besides Human space flight there are few. I think there might be a use for a very low cost HLV but shuttle derived slams the door on that.

 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.

Likewise another limitation is the deep space network. There is a limit to how many probes the deep space network can handle and it is near its limits now. In fact often data is left on a probe for play back at a later time due to not enough capacity. In fact when mars global surveyor died the extra time trying to communicate with the lost probe cost data on Cassini. Another issue is distance the further away the probe is the slower it must transmit in order for the data to be received clearly on earth.  At Pluto new horizons will only be able to do 1000bits a second.
« Last Edit: 09/01/2010 09:53 pm by pathfinder_01 »

Offline Lobo

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Re: Multiple probes on the new LV
« Reply #3 on: 09/01/2010 10:14 pm »
Over on another thread, the idea of launching multiple probes on an SDHLV was brought up as a possibility:


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).
You build like 4 duplicate probes, each maybe having an atmospheric probe that can detatch and enter the atmosphere like Galileo had.  You send the cluster on a trajectory that takes them by Jupiter, Saturn, Uranus and Neptune.  At each approach, one probe peels off and brakes into orbit.  Such a type of probe could be sent to the asteroid belt too, or be sent to Jupiter or Saturn and inserted into orbit around Europa or Titan.  (I don't know the orbital mechanics needed, but I'm guessing it would require a lot of additional propellant to get it into orbit around the moon without getting flung out into the planet's orbit.)
Flyby's like Galileo or Cassini (Moon flyby's) do produce great science.  But if you had a probe in a stable orbit around Titan, where it had instruments specifically to pierce the atmosphere and fully map the surface, with various spectrometers and gadgets to help us tell more about what's down there.  Maybe it could be like Cassini, but larger, and with some type of rover.  The probe could act as a relay for the rover, or perhaps the probe could consist of a couple of orbiters and a rover for better communications with the rover.

The flyby's of Uranus and Neptune by Voyager 2 was great, but imagine what a dedicated probe in full orbit of those planets would return?
I think probes going to those outter planets could be very similar, or t actually duplicates.  The environments are similar (cold and with little light) so you could design one and duplicate it. 
« Last Edit: 09/01/2010 10:15 pm by Lobo »

Offline Proponent

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Re: Multiple probes on the new LV
« Reply #4 on: 09/02/2010 10:14 am »
The economies-of-scale argument applies regardless of whether you launch your probes all on one vehicle or separately.  There's a limit to how much of it is done, simply because planetary scientists don't want to spend their scarce resources by sending large number of probes on to the same place.

Even Voyagers 1 and 2 were on significantly different trajectories.  They would not collectively have been able to visit as many targets had they all been launched on the same vehicle.

There's also the all-eggs-in-one-basket problem.  If large and small launch vehicles have the same failure probability, then you take a bigger risk of losing the whole show if all probes go on a single vehicle.

Offline JohnFornaro

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Re: Multiple probes on the new LV
« Reply #5 on: 09/02/2010 01:45 pm »
Quote
Actually most probes are based off earlier designs.

I think that is generally realized; I'm not sure how to word the idea of "commonality" better.

Quote
As for constellations of probes, sometimes you just don’t need battle star Galatica to get good data.

It's hard for me to imagine a constellation of four Cassinis of 2150kg as B-star Galactica, but hey.  It does seem that a fleet of 'em could get a lot more done by splitting up the workload.

Plus, there's another mission: the Deep Space Network.  On launch; multiple comsats with generally similar functionality at different predictable locations along a common trajectory, at least stretching to Pluto.  Each sat would have it's orbital injection stage, but all of them would be carried along on the probe "bus", where they peel off, along the lines that Lobo suggests.

Quote
The economies-of-scale argument applies regardless of whether you launch your probes all on one vehicle or separately.

That's true, but this notion adds the economies of a single launch.  If the logic of fewer larger launches being more economical than more smaller launches holds, then it should be payoad independent.

As to the mission profile, it would be less likely to parallel V-1 and V-2, although I like the idea of a "bus".  At first, it would be as I described; multiple probes to Mars, Jupiter, Saturn, the asteroids; where the main trajectory is known, and there are multiple targets of interest.

Quote
There's also the all-eggs-in-one-basket problem.

Every single launch has this problem.  I mentioned this in the other thread, but neglected it above.  The risk calculus is not a simple divide by four procedure.  In this example, a success rate of better than three out of four launches is quite realistic given current launch success rates.  (Ok.  Not counting NK.)  Part of the cost-benefit calculus would reveal this answer with greater confidence.  Intuitively, it seems quite feasible.

There is also the complexity of coordinating this fairly complex mechanism so as to have it successfully deploy.   We all know that single missions can fail to deploy.  This is a technical problem, tho.
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Offline clongton

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Re: Multiple probes on the new LV
« Reply #6 on: 09/02/2010 05:14 pm »
Topic: Multiple probes on the new LV

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.

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.
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Offline Space Invaders

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Re: Multiple probes on the new LV
« Reply #7 on: 09/02/2010 05:56 pm »
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).
We probably won't be around when such a window opens (more than one century into the future), and by then we'll probably have narrowed down our priorities in the Solar System quite a lot. I guess we'll be concentrating more resources in less places.

Personally, I'd love to see a couple cheap orbiters and a few cheap varied rovers sent to Mars in one go. One rover equipped for geology, another for biology, another for meteorology, etc. This way you can cover a wider range of fields. You could build them on the same basic model and change only the instruments for each specific task.

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.

Offline douglas100

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Re: Multiple probes on the new LV
« Reply #8 on: 09/02/2010 06:50 pm »
Just remember the fate of the original Voyager-twin 11 tonne Mars spacecraft to be launched by Saturn 5.

http://www.astronautix.com/craft/voyr1973.htm

I personally don't believe launching multiple planetary craft on a large launch vehicle is any more viable now than it was then.
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Offline Space Invaders

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Re: Multiple probes on the new LV
« Reply #9 on: 09/02/2010 06:57 pm »
The cancellation of those Mars-Voyagers had little to do with the launch vehicle. If funds had been available to build the probes themselves, there was at least one spare Saturn V available to launch them left over from the cancelled Apollo missions.

Offline clongton

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Re: Multiple probes on the new LV
« Reply #10 on: 09/02/2010 07:08 pm »
ESA's Ariane is designed specifically to launch multiple probes with a single launch.
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Offline 93143

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Re: Multiple probes on the new LV
« Reply #11 on: 09/02/2010 07:38 pm »
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.

If DIRECT's numbers are right, half a dozen launches per year of a J-246 (>100 mT) gets it down to (I think) around $550M/launch, even with current NASA operational practices.  (Let the contractors handle it with less oversight, and the costs could come down significantly.)  And that number includes fixed costs; if you discount those (which I think is a great idea for science payloads), $300M is not unreasonable regardless of the flight rate.

J-130 (~77 mT) without fixed costs could be less than $200M/flight, but of course without a JUS it's less useful for deep space probes...

Supposedly a Delta IV Heavy costs about $500M/launch right now (low flight rate, yeah, but it shares all its infrastructure with the regular Delta IV).
« Last Edit: 09/02/2010 08:29 pm by 93143 »

Offline douglas100

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Re: Multiple probes on the new LV
« Reply #12 on: 09/02/2010 07:44 pm »
Ariane 5 was originally sized for the Hermes spaceplane. This forced Arianespace to fly double payloads to fully utilise the vehicle's full
capacity. 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.
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Offline clongton

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Re: Multiple probes on the new LV
« Reply #13 on: 09/02/2010 07:47 pm »
Ariane 5 was originally sized for the Hermes spaceplane. This forced Arianespace to fly double payloads to fully utilise the vehicle's full
capacity. 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.

Thank you. I had forgotten about Hermes.
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Offline cgrunska

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Re: Multiple probes on the new LV
« Reply #14 on: 09/02/2010 07:54 pm »
why dont we upgrade the DSN?

Offline JohnFornaro

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Re: Multiple probes on the new LV
« Reply #15 on: 09/02/2010 08:20 pm »
Quote
...not a good idea to risk tens of billions in probes just to save a couple of billions in rockets.
There's a pretty good way to reduce all launch risks to zero, saving billions. 

The point of comparison that does not seem to be well understood is the inherent assumption that the total cost of this hypothetical multiple probe launch is equivalent to the single probe launch attempting the same tasks.   Clearly multiple probes offer higher bandwidth, multiple failure points, and the ability to achieve speciality, and allow for greater maneuverability.

Clearly, to paraphrase a DoD report on scramjets that I just read, some additional R&D work will be needed to flesh out the idea.

Also, like I mentioned, upgrading the DSN might very well be the kind of mission that could be accomplished in this fashion.
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Offline neilh

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Re: Multiple probes on the new LV
« Reply #16 on: 09/02/2010 09:22 pm »
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.

Also, how many times will the multi-probe deployment mechanism be tested in space before risking all the multi-billion probes on it?
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Offline pathfinder_01

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Re: Multiple probes on the new LV
« Reply #17 on: 09/03/2010 02:15 am »
Topic: Multiple probes on the new LV

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.

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.

Offline clongton

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Re: Multiple probes on the new LV
« Reply #18 on: 09/03/2010 02:26 am »
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.


I have misconstrued nothing. Your posts are Off Topic. Again you are using the thread to discuss a *completely off topic* idea; that the EELV is a better investment than the SDHLV. Whether that is right or not is not the point. This thread *is not* the place for that discussion. This thread presupposes the existence of the SDHLV, it does *not* ask if the SDHLV is the right vehicle. It is intended SOLELY to discuss multiple payloads on a SDHLV. THAT, and that alone, is the topic. You are OFF TOPIC, and that is the problem.
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Offline Chris Bergin

Re: Multiple probes on the new LV
« Reply #19 on: 09/03/2010 02:41 am »

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...........

Ok, so your opinion is the numbers, created by NASA, are wrong, and that the numbers on EELV, which are not available (prop/ITAR etc - there's some rough estimates out there etc), are correct. You're entitled to that opinion, but this thread is certainly not about that.

Let's avoid derailing threads, so no more thanks. Feel free to set up a thread specific to your argument, however.
« Last Edit: 09/03/2010 02:42 am by Chris Bergin »
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