Cost Is Driving NASA's Decisions on Exploration Architecture
Aviation Week & Space Technology, 05/29/2006, page 33
Frank Morring, Jr., Washington
Cost is driving NASA's decisions on exploration architecture; shuttle heritage losing emphasis
NASA's early plans to use a cost-saving "shuttle-derived" philosophy for the return to the Moon envisioned by President Bush are dropping by the wayside as closer analysis suggests other approaches may be cheaper still.
Cost -- and not its shuttle-derived first stage -- will determine where the new Crew Launch Vehicle (CLV) ultimately will be launched, even though a test flight due in as little as two years probably will fly from shuttle facilities.
Exploration managers at Kennedy Space Center are developing elaborate concepts for using the shuttle complex there to loft the CLV. But it may prove more cost-effective to refit Launch Complex 40 -- the 40-year-old Titan pad at Cape Canaveral Air Force Station that was retired after last year's final Titan IV mission -- to launch the CLV and its shuttle-replacement payload, the Crew Exploration Vehicle (CEV). Trade studies are underway, with a decision likely in the fall.
Similar studies are underway across the exploration program.
The space shuttle main engine (SSME) -- originally cast in key roles on both the CLV and the heavy-lift Cargo Launch Vehicle (CaLV) to come -- has been completely dropped from the space program after the shuttle retires in 2010. In its place will be upgrades of the J-2 upper stage engine from the Saturn V, and the RS-68 that powers Boeing's Delta IV vehicle.
"What we're talking about here is trying to get the cost to space of significant mass down as low as we can," says Jeff Hanley, program manager of the Project Constellation lunar transportation effort. "Every pound we put on the lunar surface [means] many more pounds . . . we have to get to low Earth orbit. It's a total cost, schedule and performance trade."
NASA had planned to use a mass-produced, throwaway version of the reusable SSME to power the core stage of the 125-metric-ton CaLV. But those engines would have cost about $40 million each, plus the up-front expense of a major engine redevelopment.
The RS-68, flying in clusters of five engines on two lunar missions a year, will cost about $20 million each in 2006 dollars, according to Steve Cook, manager of the Constellation Systems Launch Vehicles Project Office at Marshall Space Flight Center.
As Hanley notes, cost wasn't the only factor in the decision to go with the RS-68. Provided the CaLV can carry enough fuel, the newer engine delivers better performance getting the planned Earth Departure Stage and Lunar Surface Access Module (the lander known as LSAM) to its trans-lunar injection point in Earth orbit. To get the extra fuel capacity, the CLV project determined that the Michoud Assembly Facility in New Orleans can build 33-ft.-dia. tanks, as it did on the Saturn V first stage. Compared with the 27.5-ft.-dia. tanks in the CaLV baseline, that adds about 1 million lb. of liquid oxygen and hydrogen to the equation, which more than meets the performance requirement.
"Not only did the RS-68 meet the performance requirement, it turns out it does better to our metric point, which is trans-lunar injection," Cook says, explaining that the 650,000-lb.-thrust RS-68 can launch a slightly larger Earth-departure stage than the 418,000-lb.-thrust SSME even though its specific impulse is lower.
Still, the RS-68 must be modified for the CaLV application, and talks are already underway between NASA and the Air Force Space Command on possible cooperation to do that.
The cluster arrangement will require new gas generator exhaust manifolding and ducting, and NASA would prefer to run the engine at 106% thrust instead of the current 102%, Cook says. Ultimately, the engine might be human-rated if modifications to the current lunar-exploration architecture call for the CEV to fly on the CaLV as well as on the CLV.
The Air Force, which manages the RS-68 as part of the Evolved Expendable Launch Vehicle (EELV) program, is also considering upgrades to the engine. Hanley, who is based at Johnson Space Center, says NASA headquarters is handling talks with the service to develop an organization that could manage upgrades to the engine, which like the SSME and the J-2 is built by Pratt & Whitney Rocketdyne. One possibility under discussion is a joint program office, he says.
The decision to use an upgrade, dubbed J-2X, based on the Saturn-era engine instead of an SSME to power the cryogenic CLV upper stage added at least six months to the development time of the launch vehicle. But NASA may conduct an early flight test of the first stage -- a five-segment version of the four-segment redesigned solid rocket motor (RSRM) used to boost the shuttle -- with an inert upper stage and dummy CEV on top, Hanley says.
That test probably will be launched from KSC's Launch Complex 39 (LC 39), where the shuttle missions originate today. The mobile launcher platforms, ground-handling gear for the RSRM and workforce experience all can be adapted to the one-off test flight, if NASA decides to conduct it. Longer term, it may prove a better idea to rework the old Titan facilities at Launch Complex 40 even though KSC's transition plans for LC 39 include CLV launches (AW&ST Mar. 27, p. 54; Oct. 3, 2005, p. 26).
"It would allow us to come in and right-size the infrastructure there for the CLV, which is a much different scale than the infrastructure that supports space shuttle today," Hanley says. "[Ultimately] it would basically come down to what are we able to afford in these very critical years."
While LC 40 might better be able to handle CLV launches, LC 39 remains the logical site for processing and launching the much larger CaLV. Still, NASA Administrator Michael Griffin's hopes of trimming funding shortfalls in the shuttle program by carefully managing the transition from the shuttle to its replacements have dimmed, leaving the agency's science program to pay the near-term shuttle bills.
Even so, Hanley says, heritage from the shuttle--and other programs such as Apollo and the Pentagon's EELV--will continue to hold down costs as NASA moves its focus beyond low Earth orbit to the Moon. The CLV still will rely heavily on shuttle parts; the rocket engines chosen for the exploration program will be tested on facilities built for Saturn and other launch vehicles, and NASA intends to recycle other old infrastructure--and the old-timers who know how to operate it--for the new program.
"If we're to be able to do the Moon in a sustainable fashion, then the transportation systems we deliver have to be the most economical that we've ever been able to create,"
Hanley says. "I would encourage folks to look beyond the components of the vehicles. The real boon for Constellation will be the workforce, the experience base, the corporate knowledge and heritage from our sister programs."
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Europeans Look at Moon Role
Aviation Week & Space Technology, 05/29/2006, page 17
Edited by Frank Morring, Jr.
European Space Agency managers are studying four different scenarios for participating in a proposed U.S.-led lunar exploration program, even though the agency's clear priority will be on Mars. ESA Director General Jean-Jacques Dordain says the scenarios include participating in lunar surface exploration; conducting lunar-science missions; establishing a telecommunications/navigation network around the Moon; and developing a new space transportation system, either with Russia or the U.S. (AW&ST May 22, p. 30). Final decisions will be made at the next ESA ministerial summit in 2008. Meanwhile, scientists are preparing for the demise of the agency's Smart-1 lunar orbiter, which is scheduled to crash onto the Moon's surface Sept. 2-3 after a highly successful year-long science mission. The crash had initially been set for Aug. 17, but was shifted so it would take place on the visible side of the Moon, where the event could be more easily monitored.
Aviation Week & Space Technology, 08/07/2006, page 27
Edited by David Bond
The U.S. may be able to mount a manned mission to Mars by the late 2020s, says NASA Administrator Michael Griffin. In order to return to the Moon, NASA will need a heavy-lift launch vehicle, "the key element for any approach for going to Mars," Griffin told the Mars Society Aug. 3. The scheduled lunar arrival around 2018 will give the astronauts experience with long-duration planetary exploration, which they could use during the seven- or eight-year preparation for a Mars mission. Griffin estimates that the total mass-to-orbit needs for a Mars mission is comparable to that of the International Space Station. "If we've learned one thing from the space station, it's that the next time we need to assemble 800,000 pounds in low orbit I hope we don't try to do it 30,000 pounds at a time." Griffin says NASA will begin developing a preliminary Mars mission architecture during the next couple of years, and lunar-return hardware is being designed with Mars in mind.
"If we've learned one thing from the space station, it's that the next time we need to assemble 800,000 pounds in low orbit I hope we don't try to do it 30,000 pounds at a time."--Mike Griffin
Amen, Brother!
We need a heavy lift vehicle, and crew launch vehicle. Heavy lift to loft large payloads WITH initial habitation modules, and a smaller crew vehicle to get people up there and deploy it. Interestingly some of the old Boeing Single Stage To Orbit and Two Stage to Orbit Vehicles concepts were to deliver payloads between 500,000 and 1 million pounds into low Earth Orbit (225 to 460 metric tons.) Imagine lofting the entire ISS in one shot! (Of course if that one vehicle blew up---Ouch!)
The CaLV will be a medium-heavy lift vehicle (100,000+ kilograms) so we'll be in much better shape to build something heavy in LEO than with the Shuttle, Proton-M, and Ariane 5 boosters.
"If we've learned one thing from the space station, it's that the next time we need to assemble 800,000 pounds in low orbit I hope we don't try to do it 30,000 pounds at a time."--Mike Griffin
This is just painful... things that have been known for ~30 years are brought up by current members of the bureaucracy as if they're new epiphanies. I've seen this several times in mainstream press about the CEV and the new "Shrub Plan".
"crew need to ride in an escape vehicle"
"Don't mix crew & cargo"
"Off the shelf"
"Use what HLV capability you have in new ways, to simultaneously lift more, while using fewer launches."
"The Shuttle isn't safe" was the big laugh after Columbia. The big shocking surprise.
All due applause to Griffin, who seems to have his head on in the correct way to actually do something in space, but please!
That decision to use only the Shuttle to launch all of our contribution to the Incredible Shrinking Space Station is what killed it. A conscious decision to deliberately make it as complex and expensive and fraught with perils to budget and schedule, as you possibly can.
There you are, in the 1980s, and you have a mandate to get a space station up. What are your best options? What's the only way to launch most of a habitable workspace that's been proven by history? Skylab showed the way, and the extensive Soviet/Russian experience with Salyut/Mir.
You build a few major fuel tank-shaped volumes and put them up individually as a 2nd/3rd stage of a rocket. One of those needs to be the first thing to be met with a crew vehicle, and that's the shirt-sleeve environment they work the arm from and do EVA prep, and sleep & eat as needed. You dock large pieces together with the booster vehicle's final spurts (as was perfected in the '60s) and minimize EVA by only doing what needs it, like problem solving.
I wholeheartedly like the decision to not use the SSME, but I don't understand why the USAF has to be the middleman in getting the RS-68. I guess the bureaucratic pecking order has to take effect. Got to grease as many palms as possible (what was largely behind the decision to build the ISS as they did/tried). I can definitely understand if the USAF and/or NASA are wary of getting burned in another joint launcher effort, with mutually contradictory design requirements, but it doesn't seem like they are. Business as usual.
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"A devotee of Truth may not do anything in deference to convention. He must always hold himself open to correction, and whenever he discovers himself to be wrong he must confess it at all costs and atone for it."
Monhandas K. Gandhi
I recently learned why the SSME was not chosen for the upperstage engine for the CEV. While exploring the very interesting website NasaSpaceFlight.com, I've learned a few things about liquid fueled rocket engines. For instance, it is not possible to altitude start an SSME because it was designed to "head start", that is the weight of the propellant column in the feed lines all the way to the top of the propellant tanks, plus the gas pressure on top of that, provided the initial feed pressurization to get the turbopumps started without cavitating them. Well, as a second stage, there is an expectation of a momentary pulse of zero g: which means no SSME start. To modify one for zero-g start requires an almost complete redesign of the engine, i.e., it won't be an SSME anymore. So if you have to use a different engine, why not use one already developed and proven? Voila the J-2X is reborn!
The RS-68 is being considered for the cargo launch vehicle because it is not only cheaper than an SSME, even a 'throwaway' SSME (which doesn't exist!) but it also has greater thrust: 700,000+ lbf versus the SSME's sea level 375,000 lbf. Since you'd need 1/2 the number of engines using an RS-68 than using more expensive SSME's you not only save money, but you theoretically make the vehicle more reliable. If both the SSME and the RS-68 have exactly that same reliability (let's say it's 99%--there's no basis for this number, it's simply one I pulled from thin air), then halving the number of engines from ten to five will change the reliability from 0.99^10 = 90.4% to 0.99^5 = 95.1%. Reducing the complexity (the number of engines) will INCREASE the reliability, all other things being equal. This is another important consideration in launch vehicles....
