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Lunar Lander
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Lunar Lander
Jeff Findley wrote:
In article . com, says... On 2017-12-14 13:54, Greg (Strider) Moore wrote: As others have pointed out, Congress has to allocate the money. Is there any indication that pressure/suggestions will be made to Congress to fund a lunar lander? I take it this would come from NASA who would point to Trump's memo as justification? Doubtful. As I said, every Administration after Reagan announced plans to go to the moon and/or Mars. No funding of any significance was ever allocated to develop a full scale manned lander. This is somewhat different, in that this isn't a space policy produced by a NASA Administrator, but rather comes from a group headed by the Vice President. In a normal situation, would funding for the lander have been made at the same time as funding for Orion and the Service module as both were part of a new plan to return to the moon? Or do these first 2 normally get started years ahead of the lunar module ? This is a normal situation. Following the politically motivated (Cold War) Apollo/Saturn program, NASA's funding has not gone up much, except in rare instances where Congress is convinced that NASA won't come back to Congress for more and more money. Most proposals for manned moon or manned Mars missions in the past have fallen on deaf ears in Congress. The "won't come back and ask for more money" thing is well known by NASA, too, and has led to a number of bad decisions (like the Space Shuttle). The exception is SLS/Orion. They were funded by Congress to keep the pork flowing to former space shuttle districts after the cancellation of Ares/CEV. "The pork must flow." (Obviously updated electronics/software, updated batteries). Other than pretty much updating everything, it'll be exactly the same. Jeff Findley wrote: Pretty much updated everything. Plus it "needs" to be bigger, because we plan on staying much longer. You're not going to "dust off" the old LEM design, build it, and fly it. Today's NASA engineers and managers would never accept such a "marginal" design. The walls were thin enough aluminum in spots that you could literally jam a pencil right through the wall of it with one hand. How different COULD a lander be considering technology advancements. (aka: weight limits to get something to and from the moon). Few suppliers of the LEM hardware exist today as they did in the mid 1960s. It's been half a damn century! You can't just build new copies to the old plans because there is a hell of a lot more to it than that. Many of the then "off the shelf" parts aren't made anymore! The electronics in particular only exist in museums. No one makes parts like them anymore! Even for things that we're building constantly we have to obsolescence updates to designs because we don't have the parts to build more. Won't "new" requirements such as redundancy, thicker walls, bigger module for longer stay make the lander weight more than can be launched? Possibly. Making it more redundant and safer (higher margins in things like structural design) will add mass. But the opposing "force" is improvements in materials, manufacturing, electronics (lighter), batteries, solar cells, fuel cells, and etc. will tend to reduce mass of certain systems. Altair was bigger because it was intended to carry a crew of four. Whatever they do will probably look sort of similar to a LEM, since form tends to follow function. For a "flags and footprints" style mission, it might be a push. But, for a "moon village" program, you're going to want a bigger lander to land payloads on the moon which are bigger than the old LEM ascent stage. You'll probably wind up with two different landers, one for people that works like a LEM and one for cargo that's just a big pod that sets down and stays. Or you could, of course, go the BFR Spaceship route and build a real spaceship. Secondly, since the Service module is designed and being built before the lander, wouldn't a service module need to know the weight of the lander which it needs to push to the moon? Chicken and egg problems abound. But they're all driven by budget and what the goal is. If the goal is repeat of flags and footprints, that's a lander maybe a tad bigger than the LEM. If the goal is a lunar "base", that would drive the lander design to be bigger than the LEM. And it doesn't really 'need to know'. It just needs to be 'big enough'. The main driver will be the EUS rather than the relatively small engine on the Service Module. Either way, I doubt we'd even use the old two stage LEM architecture. I find it far more likely that a reusable lunar lander (single stage) would be developed, especially if a lunar base/village is the goal. We simply can't afford to keep disposing of such expensive hardware after a single use. That's just insane. I think that NASA will want to build something very like the LEM, but larger. But if you look at NASA's plans, they don't need a lander for a good long time yet. By then they'll be able to contract SpaceX to use BFR Spaceship. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Lunar Lander
On 17-12-18 15:26 , Jeff Findley wrote:
In article . com, says... [snip] Right now, SpaceX has done well landing stage 1s from pre-orbit altitude/speed. How does it intend to land such a huge ship from orbital speeds without need for whole skin refurb? Is the heat shield pixie dust at this point in time ? You could beef up the thermal protection system and do most of the deceleration using that [snip] But do note that on Mars, BFS would need to get most of its reentry and landing delta-V from its engines. It's just too big and too heavy to generate enough drag in the Martian atmosphere to slow it down very much. Really? In the talk on "Making Life Multiplanetary" (https://youtu.be/tdUX3ypDVwI), at about 36:10, while showing a simulation of a Mars landing, Musk says "you can remove almost all the energy aerodynamically". The screen says "Over 99% of energy removed aerodynamically". A little before that, Musk admits that "For Mars, there will be some ablation of the heat shield ... like a brake pad wearing away ... but it is a multi-use heat shield". -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
#4
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Lunar Lander
Jeff Findley wrote:
In article . com, says... The argument was that the newer components would be lighter than Apollo era modules. I pointed out that Orion was much heavier than the Apollo CM (which is comparing oranges to oranges). I have no idea of the service module weight since I don't even know if what is being built by ESA right now would be usable for a replay of Apollo (Orion + Lander) and a new SM might be needed. The Orion "command module" is physically bigger than the Apollo Command Module. But if you did a simple web search, you'd know that: https://www.quora.com/Why-does-Orion...se-of-lighter- materials-and-other-advances-to-reduce-weight-still-weigh-3-tons-more- than-Apollo Take a look at the picture on the above web page. I've told him that at least twice. I don't think facts penetrate Mayfly very well once he gets a bone in his teeth. If the stack (Lander, SM, Orion) is heavier than Apollo era stack, wouldn't the Moon orbit insertion/exit end up requiring more thrust? Unless engine efficiency more than doubled since Apollo, that would require more fuel than Apollo, woudln't it? No, the engine used on the Orion service module is not twice as efficient as the Apollo service module engine. From Reddit (check this fact yourself if you doubt it): Orion will have 1340m/s of delta-v, compared to the Apollo one which had 2800m/s. So, Orion will have less than half the delta-V of Apollo CSM. So it's actually half as capable when it comes to propulsion! I don't think that figure is correct. Wikipedia credits Orion with 1800 m/s delta-v vice the 1340 m/s that you give, which makes it about 64% of Apollo. The extended mission LM weighed a bit over 16 tonnes. The Altair lander would have weighed around 46 tonnes. I had been told that Saturn V had been the most powerfull rocket ever. Yet, now I am told that Ares could have carriued a lander that was 30 tonnes heavier when during apollo era, they were concerned with every gram of mass on the lander. I'm pretty sure that Altair would not have been launched with the CEV. That's one huge difference between Apollo/Saturn and Ares/CEV/Altair. Altair would go up on Ares V while the CEV was to go up on Ares I, remember? Multiple launches means more capability than a single launch. But it also involves a rendezvous of the two vehicles in LEO before the upper stage of Ares V puts the whole works into a TLI orbit. I honestly don't know exactly the TLI capabilities of the various SLS "designs" (they've not flown one yet). But, multiple launches solves the weight issue for any "beyond LEO" plan. Even Deep Space Gateway will take multiple launches to "build". The numbers are out there, but plans change. DSG consumes EM-2 through EM-10. Two of those are logistics and resupply missions and one of them is a long duration stay test mission, so the plan is six launches to build it. But the current thing is a diversion from going to Mars since NASA is developping stuff that won't be of use to Mars, and hasn't yet developped a plan to get to Mars, and hence can't begin to implement that plan. I'm still not convinced NASA is going back to the moon. SLS hasn't been canceled yet to free up the funding to design and build a lander. What good is a lander if they cancel the rocket that is supposed to get them there? -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Lunar Lander
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Lunar Lander
Jeff Findley wrote:
In article , says... But the current thing is a diversion from going to Mars since NASA is developping stuff that won't be of use to Mars, and hasn't yet developped a plan to get to Mars, and hence can't begin to implement that plan. I'm still not convinced NASA is going back to the moon. SLS hasn't been canceled yet to free up the funding to design and build a lander. What good is a lander if they cancel the rocket that is supposed to get them there? We don't need SLS at all if we do EOR with in orbit refueling. But now you're talking additional launches, which runs the price up. And you still need a really high energy upper stage to send the whole works somewhere. Falcon Heavy ought to be able to loft a quite capable lunar lander. ULA ought to be able to provide ACES upper stage(s) needed to get the stack to lunar orbit. Either Boeing or SpaceX can provide the space "taxi". SLS is just sucking up resources better spent on actual missions. I'm going to use payload to trans-Mars Injection, because those are the only 'constant' figures I have. Falcon Heavy is 16.8 tonnes to TMI. SLS Block 2 is 45 tonnes to TMI. None of the ULA launchers give either TLI or TMI figures, however, none of the come close to the LEO capability of Falcon Heavy so it's a fair bet they'd be well under that trying to boost to someplace farther out. BFR is in a class all by itself, of course, and will probably be ready before the DSG is done. Dragon V2 is around 10 tonnes with a 1 week duration, so Falcon Heavy could certainly send that to the moon. It can't land, though, because it doesn't carry enough fuel (only about 1.5 tonnes of fuel). Falcon Heavy doesn't have enough grunt to send an Orion stack to the Moon, much less an Orion stack plus a lander. The conclusion is that you sort of need SLS or something with similar capability. It may be a poor design and expensive, but it's what there is. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Lunar Lander
JF Mezei wrote:
On 2017-12-18 19:15, Fred J. McCall wrote: What good is a lander if they cancel the rocket that is supposed to get them there? Because Falcon 9 Heavy would be cheaper than SLS ? Except Falcon Heavy (not Falcon 9 Heavy - you've been corrected on this before, Mayfly) can't do the job. If they end up building a bigger lander, why not send just the lander and service module to the Moon and back. How difficult would it be for the lander to enter Earth orbit upon return and say dock with ISS so crew can catch a ride in a dragon back to Earth? Because that wouldn't work? If they build a bigger lander, isn't fair to state that the capsule becomes needed only to re-enter Earth's atmosphere ? No, it isn't fair to say that. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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Lunar Lander
JF Mezei wrote:
On 2017-12-19 00:41, Fred J. McCall wrote: But now you're talking additional launches, which runs the price up. And you still need a really high energy upper stage to send the whole works somewhere. The re-usability and low cost of Falcon could easily make multiple launches still much cheaper than a single launch on that SLS thing. SLS os expensive enough as it stands. It will get worse once they run out of the SSMEs they got for free from the Shuttle have have to start paying for new ones. The Orion stack without a lander weighs 25.8 tonnes. Falcon Heavy doesn't have enough grunt to get that to TLI. Dragon V2 is around 10 tonnes with a 1 week duration, so Falcon Heavy could certainly send that to the moon. It can't land, though, because it doesn't carry enough fuel So you send some mattresses to the Moon surface ahead of time :-) Even if it had enough fuel to land, would it have enough thrust to take off back into Lonar orbit? (forgetting fuel for a second). Dragon V2 has plenty of thrust. Remember that the internal engines on Dragon V2 are used as the emergency escape system during launch, so it has to be able to impart an acceleration of at least 3g. Dragon V2 has around 54 tonnes of axial thrust. The problem is that it runs out of fuel before it hits lunar escape velocity. It almost has enough fuel to get into an orbit around the Moon if it's fully fueled and certainly has more than enough thrust. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Lunar Lander
Jeff Findley wrote:
In article , says... Jeff Findley wrote: In article , says... But the current thing is a diversion from going to Mars since NASA is developping stuff that won't be of use to Mars, and hasn't yet developped a plan to get to Mars, and hence can't begin to implement that plan. I'm still not convinced NASA is going back to the moon. SLS hasn't been canceled yet to free up the funding to design and build a lander. What good is a lander if they cancel the rocket that is supposed to get them there? We don't need SLS at all if we do EOR with in orbit refueling. But now you're talking additional launches, which runs the price up. And you still need a really high energy upper stage to send the whole works somewhere. Falcon Heavy's launch costs are ridiculously low. Also SpaceX has a launch cadence for Falcon 9 that's 10x that of SLS's predicted maximum launch cadence. By the time SLS flies with humans on top, it wouldn't surprise me if SpaceX had its Texas launch site operational, giving it even more launch capacity. The "additional launches" problem simply won't be a problem in a few years, unless we stick with the max two launches per year SLS. You'd have to design a new upper stage that allowed refueling plus a tanker stage to refuel it from. If you could refuel it, the existing RP1/LOX upper stage might even have the capability for lunar work. But we're talking hardware that would be, as yet, only a gleam in someone's eye, unlike SLS. Falcon Heavy ought to be able to loft a quite capable lunar lander. ULA ought to be able to provide ACES upper stage(s) needed to get the stack to lunar orbit. Either Boeing or SpaceX can provide the space "taxi". SLS is just sucking up resources better spent on actual missions. I'm going to use payload to trans-Mars Injection, because those are the only 'constant' figures I have. Falcon Heavy is 16.8 tonnes to TMI. SLS Block 2 is 45 tonnes to TMI. None of the ULA launchers give either TLI or TMI figures, however, none of the come close to the LEO capability of Falcon Heavy so it's a fair bet they'd be well under that trying to boost to someplace farther out. BFR is in a class all by itself, of course, and will probably be ready before the DSG is done. Dragon V2 is around 10 tonnes with a 1 week duration, so Falcon Heavy could certainly send that to the moon. It can't land, though, because it doesn't carry enough fuel (only about 1.5 tonnes of fuel). Falcon Heavy doesn't have enough grunt to send an Orion stack to the Moon, much less an Orion stack plus a lander. The other possibility is Falcon Heavy with the (now downsized) Raptor powered upper stage. That would most certainly do the job. SpaceX has been getting USAF funding for this: I think BFR Spaceship might be too heavy for other boosters, but you could just use it with BFR. BFR Spaceship refueled in orbit is the whole works. It can fly to the Moon, land, take off, and return to Earth. Air Force adds more than $40 million to SpaceX engine contract by Jeff Foust, October 21, 2017 http://spacenews.com/air-force-adds-...ion-to-spacex- engine-contract/ From above: Musk said in his IAC presentation that the engine will now generate about 380,000 pounds-force of thrust That's a bit more thrust than the J-2X which was rated at 294,000 lbf thrust. One J-2X would have powered the Ares V launched EDS, so a single Raptor engine powering a Falcon Heavy upper stage ought to be quite impressive. Nobody quite knows what USAF intends to do with Raptor engines once they're through development. The conclusion is that you sort of need SLS or something with similar capability. It may be a poor design and expensive, but it's what there is. We'll have to agree to disagree. By the time SLS flies, either SpaceX or Blue Origin (which already has a high energy LOX/LH2 engine) will have fielded launch vehicles capable of replacing SLS, as long as NASA doesn't deliberately design a lunar lander "too big" for them, just like Mike Griffin did for CEV/Orion. New Glenn does what I suggested and adds a third stage so that you're fully fueled for the transit mission. That is something with "similar capability" to SLS. There's no reason Falcon Heavy couldn't do something similar, but SpaceX is aimed at BFR. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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