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Great part of the VSE moon missions may fail
I think that the best vehicle for LEO is a little, safer, cheaper (100+ times reusable) new Shuttle and that all missions beyond LEO must be made with specialized and (where possible) reusable vehicles (like a reusable LSAM) , not with 99% expendable (and expensive!) vehicles like the VSE/ESAS plan (an incredible waste of money since, after each mission, only a little capsule will come back to earth, like in the old "money-burner" Apollo program).
Months ago I've evaluated the total cost (including shared R&D) of the next moon missions around $8 billion each, but the biggest problem inside the VSE architecture is the (very bad!) choice of TWO launches (or, exactly, the "one-and-half" launch architecture).
I think that it is a big risk for the success of the missions and may be the first reason of the fail of great part of them, also, if that problem will happen in 2020, nothing will be possible to solve it and the VSE will die!
The story of astronautics is not a story of "launches" but a story of "delays", the cost of rockets/payloads and the value of human lifes are too high to launch them without verify that ALL is PERFECT, no matter if that need hundreds of controls, tests and many weeks or months of delay!
After the two Shuttles' disasters, all the future manned missions (with or without the Shuttle) will need (and will have!) a multiplied attention to big problems and to little details before each launch of the (old) Shuttle or the new (then "experimental" and poor tested) CEV/CLV.
But, while in the past (manned and unmanned) launches a delay was only a problem of "more time and money to spend", with the future "one-and-half-launch" missions architecture, the "sum of delays" of the "second launch" of a mission, will equal to a TOTAL MISSION FAILS with $8+ billion lost!
The origin of that risk is the low "orbital life" of the first launch (the CaLV with EDS and LSAM), due to storage problems of cryogenic propellents in the space; if the EDS and LSAM will stay too much time in space (waiting for the CEV) they can't be used (or the risk to use them will be too high) and the mission ends.
In the first version of the ESAS architecture the "orbital wait time" was of only one month; now the plan is changed, because NASA wants three months of "orbital life" for the EDS and LSAM, but this is not sufficient to avoid the risk of fail, if you think that the next Shuttle launch will be one year after the last flight, first due to a foam (foam!!!!!!) problem and over two months of it simply to change a little sensor of the external tank!!!
Just image how many problems may happen in 2020 with two new rockets (shuttle derived...) and two new (and very complex) vehicles like the CEV and the LSAM made with thousands of parts and sensors!
Every time the "sum of delays" will exceed three months, the mission will fails, and, don't forget that, in 2020-2025, the number of moon missions will be only two per year, about 12 in total, NOT dozens!
I don't know how many moon missions will fail due to "second launch" delays, but, if you see the story of last 20 years of the Shuttle and ISS programs (with months or years of delays for every single "step" or problem!), the number of aborted VSE moon missions due to a "sum of delays" may be very very high.
With 12 mission planned, the most optimistic figure is of 2-4 missions aborted due to "delays", but, if the number of aborted missions will be higher than 30%, the VSE/ESAS plan will die and the entire manned space program will restart from ZERO with a possible "VSE 2.0" to come back on the moon in 2035...
The ONLY way to avoid this terrifying scenario is to CANCEL the "one-and-half" launch architecture and move to a new one based on a Single Launch Vehicle, like the successful SaturnV of the Apollo program.
The new S.L.V. (that I suggest to call "SaturnVI" to born lucky) can be made (as planned) using the same parts of the CaLV but with more engines to launch a total EDS/CEV/SM/LSAM weight of 145+ tons (see the concept image in this page) instead of only 125 tons.
Probably you think that a mission made with a big SLV is too risky for the astronauts, but that is not true for (at least) five good reasons:
1. the 100% successful SaturnV flights (made with '60s technology!) clearly demonstrate that an SLV can be 100% safe for astronauts,
2. thousands of little and big rockets launched in 50 years demonstrate that all rockets can be 100% safe or 100% dangerous, it's not a problem of "dimension",
3. the CLV with its single SRB may be more unstable than a CaLV because, the latter, with two SRBs and five throttleable SSMEs, will have a better control of its thrust and its trajectory and LESS "G" for the astronauts, like with the Shuttle,
4. the cargo-only CaLV will be indispensable in all moon missions (and very expensive) then it MUST be designed, built and tested to be reliable,
5. the life of the astronauts don't depends from the reliability of the rocket (CLV or CaLV) but (entirely) from the reliability of the LAS; if the LAS will be very fast and 100% reliable, the life of the astronauts will be 100% safe (on ANY rocket, no matter if it is little or big, old or new, reliable or not).
But, how to build the SLV? I think that the right choice must be one of these three options:
a) build a 150-tons-payload "SuperCaLV" with three 4-segments SRBs and three SSMEs as first stage (and three J2X for the second stage/EDS); the SRB must be exactly the same of the Shuttle (without any independent energy and controls) to save up to three years of time and up to $3 billion of research and development to modify the SRB to a 5-segment version (with more expensive changes for the CLV)
b) build the 125-tons CaLV (as planned) but resize the CEV/SM/LSAM/EDS for a 3-astronauts moon mission of 10 days (instead of 4-astronauts for a week) because that change will need only a ton of extra food, water and oxygen and not a 33% bigger CEV, LSAM, EDS, etc.
c) build a 100-tons CaLV, with the same design of the 125-tons version, but with two 4-segments SRBs instead of 5-segment SRB; the moon missions will be with 3-astronauts for 10 days and the exploration & science hardware for 5+ missions will be sent on the moon before the first manned mission with a 18 tons payload cargo-LSAM.
The "c" option is the best choice because the 100-tons-SLV will be safer and 25% smaller, then, built in less time and with less money (about $5 billion less for R&D and 25% less of hardware costs per launch) that means 50% MORE MOON MISSION with the same budget!
The SLV can't be used to launch the CEV for the ISS, but the CEV is COMPLETELY UNNECESSARY for the ISS, because...
1. in 2015 the ISS will be older than Mir then (like the Mir) will be (very probably) crashed in the pacific ocean within the next 5 years,
2. the half-made ISS is (and will be) only for 3 astronauts that don't need so much to live and work; in the last 4 years the ISS survived well without (both) Shuttle and CEV, with only a few Soyuz and Progress,
3. in 2015 will be many cheaper cargo and crew vehicles for the ISS, like the reliable Soyuz (or a better Soyuz 2.0), Progress, ATV, Kliper, Shenzhou (I think that an ISS cooperation with China will be 100% sure in the next years) and (probably) some orbital vehicles from India and privates (like the CXV)
4. with a cost of $1 billion per launch and $250+ million per "seat" the CEV will be TOO EXPENSIVE for all European and little countries' space budgets, then, it will be used only for a few launches (probably less than a dozen!) with American astronauts.
I think that to-day's NASA faces only TWO alternatives (and it can't have both!): build the CEV/CLV for the "one-and-half" launch moon missions' architecture (and a few ISS missions) with 30-70% risk to fail (due to a "sum of delays") OR build the SLV that can't be used for ISS, but may have a 90%+ successful moon missions also if each launch will delay of years!!!!!
To be exact, the CEV can be launched also for orbital missions with the SLV, but its cost per launch will be too high; a possible solution is to use the SLV to launch a mix of big cargo + crew for orbital missions.
The SLV (especially the 100-tons low cost version!) has many advantage vs. the 125-tons CaLV and the one-and-half launch architecture, but, in synthesis, the MAIN ADVANTAGES are:
1. up to 100% successful moon missions, avoiding the risks of a "sum of delays" of the second launch,
2. a faster and safer mission and without the risk that a mission will fails for an error in the insertion to the right orbit of one or both vehicles, that will never rendez-vous,
3. an incredible quantity of MONEY saved (especially with the 100-tons SLV): $15 billion saved for R&D and 25 launches' hardware of the CLV, $8+ billion saved for R&D and 20 launches' hardware of the 2o% smaller 100-tons SLV with ready available 4-segments SRBs, $5 billion saved for 20 launches' hardware of the "3-seats" and 25% smaller CEV/LSAM (with a 20% smaller SM and EDS) and for one launch pad instead of two, less assembly facilities and time, less transport costs, etc.
4. an incredible quantity of TIME saved to build the CLV, modify and test the SRB to work alone on the CLV and with 5-segments on, both, the CLV and the CaLV, etc.
5. as a result of the first four points, NASA will be able to make MORE moon missions (I think +50%), in LESS time (up to four missions per year from 2015 instead of two moon missions per year from 2020+) and with the SAME budget!!!
With the SLV the first moon mission may be launched in 2012-2015 instead of 2018-2020 or (worst) in 2030-2035 if the one-and-half-launch architecture will fails too much times!
April 12 - 2006
Another critical problem: After end writing this article I've realized that the "one-and-half" launch architecture is much more unreliable than explained here. I think that 95 days only of loither time in orbit of the first part of the hardware of each missions is too little to have a good number of successful missions, but the real time available for the second launch is much less than 95 days!
To have an efficient moon exploration, the first 10-20 missions must land in the same place of the moon to reuse the hardware sent on the surface (rovers, etc.) and the exploration must be made for one week in day light, then, not all the 95 days available can be used to launch the CEV. To arrive while the moon daylight and explore it for a week, the CEV/LSAM/EDS must leave the earth orbit when on the moon there is the night. That reduce the time available to HALF, but, add the time of the travel, the time in moon orbit, the earth to orbit launch windows (since the moon launch is not equatorial), etc. etc. etc.
In 95 days, the total number of HOURS available for the second launch (to meet all required specs) will be of ONLY A FEW DOZENS HOURS! If the delays of the second launch will happen in these few CRITICAL HOURS the entire mission will fail. Then, the risk of missions fail with the one-and-half launch architecture is much more higher than explained in this article and may reach 80-100%!!!
Copyright © 2006 Gaetano Marano - All rights reserved - The images used for the SLV drawing are © NASA