The Bush Administration has made no decision on the end date for ISS operations. We are, of course, concerned that Station operating costs after 2016 will detract from our next major milestone, returning to the Moon by 2020. But while the budget does not presently allocate funds for operating ISS beyond 2016, we are taking no action to preclude it. Decisions regarding U.S. participation in ISS operations after 2016 can only be made by a future Administration and a future Congress. I am sure these will be based on discussions with our international partners, progress toward our Exploration goals, utility of this national laboratory, and the affordability of projected ISS operations. Again, we plan to keep our commitments to our partners, utilizing ISS if it makes sense.
Mark Max Q - 23/1/2008 1:19 PM"So, while we might wish that “off the shelf” EELVs could be easily and cheaply modified to meet NASA’s human spaceflight requirements, the data says otherwise. Careful analysis showed EELV-derived solutions meeting our performance requirements to be less safe, less reliable, and more costly than the Shuttle-derived Ares I and Ares V."Would love to hear what the EELV folks think of that.
while we might wish that “off the shelf” EELVs could be easily and cheaply modified to meet NASA’s human spaceflight requirements, the data says otherwise.
Antares - 23/1/2008 1:46 PMSing with me!:"When you own the information, you can bend it all you want." (John Mayer.)
stockman - 23/1/2008 12:11 PMQuoteThe Bush Administration has made no decision on the end date for ISS operations. We are, of course, concerned that Station operating costs after 2016 will detract from our next major milestone, returning to the Moon by 2020. But while the budget does not presently allocate funds for operating ISS beyond 2016, we are taking no action to preclude it. Decisions regarding U.S. participation in ISS operations after 2016 can only be made by a future Administration and a future Congress. I am sure these will be based on discussions with our international partners, progress toward our Exploration goals, utility of this national laboratory, and the affordability of projected ISS operations. Again, we plan to keep our commitments to our partners, utilizing ISS if it makes sense. I found this paragraph interesting in regards to ISS... it appears that 2016 retirement is FAR from a done thing after all.
Chris Bergin - 23/1/2008 11:30 AMhttp://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdfHere's the part that will make many a coffee be spat over screens in Denver etc. snip... and abort from the Delta IV exceeds allowable g-loads. snip
edkyle99 - 23/1/2008 11:31 AMI see the most important theme here as follows. Griffin thinks he is building an architecture to go to Mars, not to ISS or even to the Moon really. (Never mind that Congress just zeroed the Mars budget!) The Ares/Orion architecture will look better cost-wise than any alternative under the assumption that it will be used for Mars. But what if it is not used for Mars? - Ed Kyle
Thomas - 23/1/2008 2:46 PMI'm glad to see Griffin emphasizing that the switch to the 5 segment booster/J-2X upper stage was for the purposes of reducing the cost/development time of the Ares V and not due to any inherent weakness in the SRB or SSME..
edkyle99 - 23/1/2008 2:31 PMI see the most important theme here as follows. Griffin thinks he is building an architecture to go to Mars, not to ISS or even to the Moon really. (Never mind that Congress just zeroed the Mars budget!) - Ed Kyle
Jim - 23/1/2008 12:02 PMQuoteThomas - 23/1/2008 2:46 PMI'm glad to see Griffin emphasizing that the switch to the 5 segment booster/J-2X upper stage was for the purposes of reducing the cost/development time of the Ares V and not due to any inherent weakness in the SRB or SSME..That is after spin. Ares V was to use the SSME also. The change was due to issues with airstarting the SSME and making it expendable. Sound like a weakness to me
Norm,
I would like to challenge both the DIRECT group and the EELV group to respond to this speech on a point-by-point basis.
While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion. The conclusion I would draw is that if cryogenic propellant storage technologies are so critical--develop them. Don't let the existing state of the art in propellant handling drive transportation system decisions for projects that won't be undertaken for 15-20 years!
There are current technologies under development that could yield very low to zero boiloff of cryogenic propellants. For a six launch architecture, especially if the LH2 is being used in some sort of nuclear or solar thermal system (where the hydrogen is used gradually over the course of the trip to and from Mars), you already need a system that can keep LH2 for months to years, so extending that technology further so that boiloff during mission assembly isn't an issue.
Is 2025-2030 really so close that we can't afford to do this right and actually develop the technologies we need instead of trying to kludge by with existing technologies?
Once you have the boiloff issue reduced or solved, that ~500klb of hydrogen ceases to be a headache, and begins to be an opportunity. That's a lot of demand for propellant in orbit, and it can be supplied commercially. You're already going to need propellant transfer technologies anyway if you have to launch the hydrogen in multiple launches, so what's to stop launching it in even smaller launches? Use a depot if you're worried about too many docking events with your mars ship.
I'm sure the DIRECT guys can bring up other points, but that's one that stuck out to me. If one of his key arguments for why you need Ares V is hydrogen boiloff, he's going about it in the wrong way.
~Jon
jongoff - 23/1/2008 10:18 AMthe control of hydrogen boiloff in space is one of the key limiting technologies for deep space exploration, the need to conduct fewer rather than more launches to LEO for early Mars missions becomes glaringly apparent.While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion.
While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion.
Thomas - 23/1/2008 2:46 PMI'm glad to see Griffin emphasizing that the switch to the 5 segment booster/J-2X upper stage was for the purposes of reducing the cost/development time of the Ares V and not due to any inherent weakness in the SRB or SSME. Too many Ares I detractors either don't realize this or intentionally mislead their audience.
Jon may have something here. Propellant boiloff is an issue, but it does scream out as a problem to be solved by a new technology or strategy and not by a new and expensive hulking rocket. Griffin does seem to assume that technology for various things including propellant storage will remain static. Without money they may remain static anyway, but if there's no money then it's a moot point IMO.
Tim S - 23/1/2008 2:39 PMWell said Mr Griffin.We're not talking about U-Haulers for cargo here. We're talking manned space flight. EELV folks on here need to stick to what they know.
Tim S - 23/1/2008 3:39 PMWell said Mr Griffin.We're not talking about U-Haulers for cargo here. We're talking manned space flight. EELV folks on here need to stick to what they know.
Tim S - 23/1/2008 12:39 PMWell said Mr Griffin.We're not talking about U-Haulers for cargo here. We're talking manned space flight. EELV folks on here need to stick to what they know.
Chris Bergin - 23/1/2008 11:30 AMhttp://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdfHere's the part that will make many a coffee be spat over screens in Denver etc. snipThe Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission. EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I. We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.ship
Norm Hartnett - 23/1/2008 1:57 PMNot the Moon and not Mars but beyond, in other words a system that has the versatility to go to any place in space that is reasonable within the framework of the next thirty years.
As to the Constellation architecture looking better cost-wise than any alternative for Mars IMO Ross has already addressed this in the DIRECT discussion. And to address your question, if it is not used for Mars there are still the NEOs, Mars' moons, and Venus.
Danny Dot - 23/1/2008 3:21 PMQuoteChris Bergin - 23/1/2008 11:30 AMhttp://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdfHere's the part that will make many a coffee be spat over screens in Denver etc. snipThe Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission. EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I. We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.shipWhat is the lift capability of Delta and Atlas heavy? I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.Danny Deger
Thomas - 23/1/2008 3:38 PMWhy do people seem so surprise that the ARES (hello!!!!!!) series of vehicles have Mars as an ultimate destination?
edkyle99 - 23/1/2008 4:43 PMQuoteThomas - 23/1/2008 3:38 PMWhy do people seem so surprise that the ARES (hello!!!!!!) series of vehicles have Mars as an ultimate destination? Then why is NASA betting its foreseeable future on lunar exploration? - Ed Kyle
A bigger launch vehicle is always going to cost less on a $/kg payload basis when it is compared to a smaller launch vehicle if the payload requirements are large enough or the program time frame is long enough, or both. Ares V outhauls Direct, and so will always beat it at that cost-comparison game when it comes to Mars missions that start in 2030, require a million pounds of payload in LEO for each mission, and are part of a Mars exploration program that continues forever.
edkyle99 - 23/1/2008 4:38 PMQuoteDanny Dot - 23/1/2008 3:21 PMQuoteChris Bergin - 23/1/2008 11:30 AMhttp://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdfHere's the part that will make many a coffee be spat over screens in Denver etc. snipThe Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission. EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I. We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.shipWhat is the lift capability of Delta and Atlas heavy? I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.Danny DegerMy recollection is that NASA's study showed that the EELVs couldn't lift the payload when restricted to the low-loft ascent profiles. They would also carry a lot of LAS mass, etc., that would limit them compared to a typical satellite in a shroud type payload. Together, these factors dramatically cut the EELV mass delivery capabilities for a CEV. - Ed Kyle
jongoff - 23/1/2008 11:50 AMFor existing, very low launch rate vehicles (EELV, SDVs, etc), you might have a point, but I'd be careful with generalities like that.
Norm Hartnett - 23/1/2008 2:57 PMAnd to address your question, if it is not used for Mars there are still the NEOs, Mars' moons, and Venus.
Venus?! Might be a little warm for the crew...
One non-technical reason I don't like the Ares I/Ares V approach is that it allows Congress to cancel the heavy lift portion that's needed for beyond-ISS missions while still preserving some basic spaceflight capability. When was the last time NASA completed a program in its entirety with all planned enhancements? Just take a look at ISS! I think getting heavy lift launch vehicle capability up front is the only way to ensure it doesn't get cut when the inevitable delays and cost overruns occur.
savuporo - 23/1/2008 4:17 PMQuotejongoff - 23/1/2008 11:50 AMFor existing, very low launch rate vehicles (EELV, SDVs, etc), you might have a point, but I'd be careful with generalities like that.Considering Dnepr vs EELV launch costs per pound, the point just does not work.
Antares - 23/1/2008 1:46 PMIt's kinda funny that 2.5 years after ESAS, he's still having to sell the architecture. By now, one would think it could stand on its own merits.
landofgrey - 24/1/2008 1:59 AMQuoteAntares - 23/1/2008 1:46 PMIt's kinda funny that 2.5 years after ESAS, he's still having to sell the architecture. By now, one would think it could stand on its own merits.The speech was for the benefit of understanding for those who have questions, and I'm sure it was the last thing Griffin wanted to talk about... yet... again. Simply put, ESAS has already been sold to everyone who matters: Congress, industry and the majority of the public who care, which is why it is now essentially a matter of law. The opposition from a vocal minority of the public, scientists and engineers notwithstanding, the architecture has been "sold" and most people agree with the basic direction. I know that doesn't sit well with proponents of EELV-derived solutions or DIRECT, but some people also still don't accept that Ron Paul isn't going to get elected or realize they're in the 5% minority (backhanded analogy). Presonally, I just hope we don't get bit by the decisions that have been made.
landofgrey - 23/1/2008 8:59 PMSimply put, ESAS has already been sold to everyone who matters: Congress, industry and the majority of the public who care, which is why it is now essentially a matter of law.
edkyle99 - 23/1/2008 2:38 PMQuoteDanny Dot - 23/1/2008 3:21 PMQuoteChris Bergin - 23/1/2008 11:30 AMhttp://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdfHere's the part that will make many a coffee be spat over screens in Denver etc. snipThe Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission. EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I. We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.shipWhat is the lift capability of Delta and Atlas heavy? I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.Danny DegerMy recollection is that NASA's study showed that the EELVs couldn't lift the payload when restricted to the low-loft ascent profiles. They would also carry a lot of LAS mass, etc., that would limit them compared to a typical satellite in a shroud type payload. Together, these factors dramatically cut the EELV mass delivery capabilities for a CEV. - Ed Kyle
Oh, please. Do I have to write out the obvious disclaimer every time? The one that says "all other things being equal"? As in comparing launch vehicles built in the same country, using the same currency, the same labor laws, the same safety rules, the same environmental regulations, etc.? NASA isn't going to use Russian-built launch vehicles to fly to Mars, or the Moon, or where ever, unless national policy changes. If that happens, then we can sit down and compare Dnepr per pound versus Proton per pound, etc..
landofgrey - 23/1/2008 5:59 PMQuoteAntares - 23/1/2008 1:46 PMIt's kinda funny that 2.5 years after ESAS, he's still having to sell the architecture. By now, one would think it could stand on its own merits.The speech was for the benefit of understanding for those who have questions, and I'm sure it was the last thing Griffin wanted to talk about... yet... again. Simply put, ESAS has already been sold to everyone who matters: Congress, industry and the majority of the public who care, which is why it is now essentially a matter of law. The opposition from a vocal minority of the public, scientists and engineers notwithstanding, the architecture has been "sold" and most people agree with the basic direction. I know that doesn't sit well with proponents of EELV-derived solutions or DIRECT, but some people also still don't accept that Ron Paul isn't going to get elected or realize they're in the 5% minority (backhanded analogy). Presonally, I just hope we don't get bit by the decisions that have been made.
kevin-rf - 23/1/2008 9:42 PMNoticed he said nothing about the five segment thrust oscillation issues
Chris Bergin - 23/1/2008 4:01 PMQuotelandofgrey - 24/1/2008 1:59 AMQuoteAntares - 23/1/2008 1:46 PMIt's kinda funny that 2.5 years after ESAS, he's still having to sell the architecture. By now, one would think it could stand on its own merits.The speech was for the benefit of understanding for those who have questions, and I'm sure it was the last thing Griffin wanted to talk about... yet... again. Simply put, ESAS has already been sold to everyone who matters: Congress, industry and the majority of the public who care, which is why it is now essentially a matter of law. The opposition from a vocal minority of the public, scientists and engineers notwithstanding, the architecture has been "sold" and most people agree with the basic direction. I know that doesn't sit well with proponents of EELV-derived solutions or DIRECT, but some people also still don't accept that Ron Paul isn't going to get elected or realize they're in the 5% minority (backhanded analogy). Presonally, I just hope we don't get bit by the decisions that have been made.Got to admit that's a great post.
CFE - 23/1/2008 5:11 PMOf course, the question must be asked why Orion weighs so much to begin with. In my reading of the ESAS report, I have yet to find any rationale why the capsule is so huge for such a minuscule crew.
Antares - 24/1/2008 12:45 AMQuoteTim S - 23/1/2008 2:39 PMWell said Mr Griffin.We're not talking about U-Haulers for cargo here. We're talking manned space flight. EELV folks on here need to stick to what they know.I hope you get up early and have Sen. Shelby on speed dial. Some morning in the not too distant future when the sun rises over the Atlantic, the dawn will be cast on a winged vehicle atop an EELV pointed at Space. Wisps of GOX will be venting from its haunches (no vent arm needed). Ice will be forming and falling away in the humid air. Turbopumps will spin and steam and maybe carbon dioxide will rush forth, without a hint of HCl or molten aluminum polluting the precious refuge.An hour or so later, there will be much rejoicing in Denver, Florida, LA AFB, and the south side of the Tennessee River in Northern Alabama. Those on the north side of the river will still be wondering why their square-tired Ferrari is still 5 years from launch and there's a Ford in space. That night, all those Congressmen who don't usually care about Space will look skyward and have their own Sputnik moment as the "cargo" orbits past and realize there's a chance America may still be able to sell burgers on the moon before we have to put up with free samples of bourbon chicken.We'll stick with what we know: fulfilling customer requirements, market-driven systems, true risk management, successful product development, cost-effective mission success.Please, go do Ares V. Just stop wasting time and money on another 50K-class launch vehicle when cheaper, adequate ones already exist.
meiza - 24/1/2008 8:23 AMI think four crew is justified by enabling two EVA pairs. If you have three, it's dangerous if one goes alone and thus you have to move as a group of three and then it's not that much more useful than just two since you can't spread out much. So either 2 or 4.
James Lowe1 - 24/1/2008 11:58 AMThread deleted back to before the arguments. Uh oh, too far back it seems
kevin-rf - 23/1/2008 12:52 PMQuoteJames Lowe1 - 24/1/2008 11:58 AMThread deleted back to before the arguments. Uh oh, too far back it seems Wait, you censor'd Chris? Wow that takes some somtin or other
edkyle99 - 23/1/2008 3:38 PMsnipMy recollection is that NASA's study showed that the EELVs couldn't lift the payload when restricted to the low-loft ascent profiles. They would also carry a lot of LAS mass, etc., that would limit them compared to a typical satellite in a shroud type payload. Together, these factors dramatically cut the EELV mass delivery capabilities for a CEV. - Ed Kyle
TrueGrit - 24/1/2008 4:50 PMAnd finally... By the time the administrators successor gets around to begging from congressional money for the heavy booster ULA will have moved on to RL-60 and ACES. They'll also conveniently forget this speech when the same successor comes asking for support because NASA is stuck in LEO again.
CFE - 24/1/2008 8:30 PMQuoteTrueGrit - 24/1/2008 4:50 PMAnd finally... By the time the administrators successor gets around to begging from congressional money for the heavy booster ULA will have moved on to RL-60 and ACES. They'll also conveniently forget this speech when the same successor comes asking for support because NASA is stuck in LEO again.Is RL-60 still an active program? P&W hasn't mentioned it in press releases since 2003.As far as congressional language mandating a "heavy lift launch vehicle" is concerned, all I have to say is that everybody's got a different definition of what "heavy lift" is. After all, they don't call it a Delta IV Heavy for nothing.
clongton - 24/1/2008 4:31 PMNASA is required by law to build a heavy lift launch vehicle to use in execution of the VSE.Notice that it required the "use the personnel, capabilities, assets, andinfrastructure of the Space Shuttle program" to build it. A Shuttle-Derived launch vehicle was mandated by this authorization act.
Lee Jay - 24/1/2008 5:48 PMQuoteclongton - 24/1/2008 4:31 PMNASA is required by law to build a heavy lift launch vehicle to use in execution of the VSE.Notice that it required the "use the personnel, capabilities, assets, andinfrastructure of the Space Shuttle program" to build it. A Shuttle-Derived launch vehicle was mandated by this authorization act. Then why aren't they building one (or two)?
meiza - 24/1/2008 3:31 PM5% is 1.25 t from 25 t. So 23.75 t. I wonder with the new RS-68... And Atlas V heavy had more performance margin, I think it was 28 t to 28 degrees...
savuporo - 25/1/2008 12:47 AMQuoteLee Jay - 24/1/2008 5:48 PMQuoteclongton - 24/1/2008 4:31 PMNASA is required by law to build a heavy lift launch vehicle to use in execution of the VSE.Notice that it required the "use the personnel, capabilities, assets, andinfrastructure of the Space Shuttle program" to build it. A Shuttle-Derived launch vehicle was mandated by this authorization act. Then why aren't they building one (or two)?Isnt NASA is successfully ignoring a bunch of other acts and laws, signed earlier ? Something about Space Settlement in 88, space commercialization acts and stuff like that ?
clongton - 25/1/2008 6:18 AMQuotesavuporo - 25/1/2008 12:47 AMsnipIsnt NASA is successfully ignoring a bunch of other acts and laws, signed earlier ? Something about Space Settlement in 88, space commercialization acts and stuff like that ?They claim that they are. But anyone who knows anything is fully aware that is a load of poppycock. All of their claims are not intended for those of us who actually know better. They are intended for those in the public and in government who can make budgetary decisions but don't know enough about the subject to actually see the flaws in the logic or the half-truths in the statements.
savuporo - 25/1/2008 12:47 AMsnipIsnt NASA is successfully ignoring a bunch of other acts and laws, signed earlier ? Something about Space Settlement in 88, space commercialization acts and stuff like that ?
jongoff - 23/1/2008 3:18 PMWhile one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion. The conclusion I would draw is that if cryogenic propellant storage technologies are so critical--develop them. Don't let the existing state of the art in propellant handling drive transportation system decisions for projects that won't be undertaken for 15-20 years! ~ Jon
landofgrey - 23/1/2008 7:59 PMQuoteAntares - 23/1/2008 1:46 PMIt's kinda funny that 2.5 years after ESAS, he's still having to sell the architecture. By now, one would think it could stand on its own merits.The speech was for the benefit of understanding for those who have questions, and I'm sure it was the last thing Griffin wanted to talk about... yet... again. Simply put, ESAS has already been sold to everyone who matters: Congress, industry and the majority of the public who care, which is why it is now essentially a matter of law. The opposition from a vocal minority of the public, scientists and engineers notwithstanding, the architecture has been "sold" and most people agree with the basic direction. I know that doesn't sit well with proponents of EELV-derived solutions or DIRECT, but some people also still don't accept that Ron Paul isn't going to get elected or realize they're in the 5% minority (backhanded analogy). Presonally, I just hope we don't get bit by the decisions that have been made.
Is RL-60 still an active program? P&W hasn't mentioned it in press releases since 2003.
pad rat - 25/1/2008 11:15 AMThere is suffficient wiggle room built into that language that would allow NASA to deviate in any way it chooses."...to the fullest extent possible consistent with a successful development program..."
meiza - 26/1/2008 11:31 AMDavid, he probably means nuclear thermal rockets (NTR) which run on hydrogen only. Their use is outlined in the Mars reference mission 3.0.
Zach - 26/1/2008 6:18 PM NTR is certainly the likely interpretation of Griffin's comment. But if Griffin believes that hydrogen boilof is a key limiting technology in an NTR world he has his priorities mixed up: "control of hydrogen boiloff in space is one of the key limiting technologies for deep space exploration". Development of the reactor, human rating it, getting approval to launch said reactor, and operating it, especially in Earth orbit make hydrogen storage pale in comparison.
Note that he said 'one of' not 'the'. All the enabling technologies have to be in place for something to be enabled. A reactor that lacks fuel because it has all boiled away is going to look pretty silly, as is a stock of LH with no way to make use of it.
The thing with control of boiloff is that it is 'dual use' - the technology benefits both Chemical and Nuclear Thermal propulsion.
Rick
sbt - 27/1/2008 6:23 AMQuoteZach - 26/1/2008 6:18 PM NTR is certainly the likely interpretation of Griffin's comment. But if Griffin believes that hydrogen boilof is a key limiting technology in an NTR world he has his priorities mixed up: "control of hydrogen boiloff in space is one of the key limiting technologies for deep space exploration". Development of the reactor, human rating it, getting approval to launch said reactor, and operating it, especially in Earth orbit make hydrogen storage pale in comparison.Note that he said 'one of' not 'the'. All the enabling technologies have to be in place for something to be enabled. A reactor that lacks fuel because it has all boiled away is going to look pretty silly, as is a stock of LH with no way to make use of it.The thing with control of boiloff is that it is 'dual use' - the technology benefits both Chemical and Nuclear Thermal propulsion. Rick
jongoff - 23/1/2008 2:18 PMWhile one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion. The conclusion I would draw is that if cryogenic propellant storage technologies are so critical--develop them.
While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion. The conclusion I would draw is that if cryogenic propellant storage technologies are so critical--develop them.
Norm Hartnett - 23/1/2008 1:30 PMThis speech is one of the reasons I respect Dr. Griffin. The man can really put together a good speech and this year he has done several of them. I still consider him one of the most dynamic leaders NASA has ever had.I would like to challenge both the DIRECT group and the EELV group to respond to this speech on a point-by-point basis.Good luck.
Lampyridae - 31/3/2008 7:49 AMThere are other things to feed NTRs... such as Ammonia, Isp of about 600 compared to 800 for LH. That would do for return propellant.
neviden - 31/3/2008 12:23 PMQuoteLampyridae - 31/3/2008 7:49 AMThere are other things to feed NTRs... such as Ammonia, Isp of about 600 compared to 800 for LH. That would do for return propellant.In that case they are better of with simply using chemical rockets. NTRs are borderline useful as it is with 800 s.If NASA thinks about going nuclear then NEP presents much better option. But if they would develop electric propulsion system in MW range, they could even remove the need for nuclear reactor and go with SEP.
Lampyridae - 1/4/2008 3:36 AMYou are putting all your eggs in one basket with a big launcher, but unlike eggs you can't make a Mars ship omelette with 5 eggs instead of 6. ISS is a 4 egg omelette when it was meant to be 6, after all. And it's still not ready to be served.
Lampyridae - 1/4/2008 3:36 AMNow, with the Europeans and Russians, neither seem about to stump for a new, larger launcher but both are keen on the moon. The only approach I've ever seriously heard is along the lines of EELV.