jackson@ttidcb.UUCP (Dick Jackson) (12/05/85)
There's talk about an international manned Mars expedition. Naturally I'm all for it. Is there a generally agreed best way to go? My very uninformed thoughts are: - A very modular spacecraft, for redundancy - Artificial gravity through spinning - Return booster sent separately to Mars orbit My spaceship, assembled in EO of course, would have at least three manned modules plus landers which would fit together in a package for the acceleration phase. Once at cruise the manned units would be sent out on the end of tethers to form a sort of spider web, then the whole thing would be spun up. For entry into Mars orbit the thing would be pulled together again. Once in orbit, the manned units could possibly be sent off on diverse missions, e.g. rendezvous with the moons. I don't really care if this makes total sense, the main point is that system design for the Mars mission seems to offer a very rich field for innovative spacefaring ideas. Who's next? Dick Jackson
dietz@SLB-DOLL.CSNET (Paul Dietz) (12/07/85)
A manned Mars trip should have low priority. The following items are more important: (1) Cheaper transport to low earth orbit (2) Reusable OTV's (robotic or remote controlled) (3) Storage areas in LEO and GEO for parts & fuel for OTV's (4) A LEO space station (5) A GEO space station (6) Visits to asteroids co-orbital with earth, if any exist (7) A lunar base (8) Visits to some Apollo/Amor asteroids It really makes little sense to visit Mars until we can do so economically. This will require more infrastructure around earth if we want to establish a base there at a reasonable cost. The payback from asteroid visits is also likely to be higher, if large amounts of mass can be returned to earth orbit. Of course, there will be scientific benefits from a Mars mission, but the results would be expensive, and more science could be done on earth (in other fields) for the same money. Of the eight points I listed above, (1) is the most important for making a Mars mission practical. A Mars ship will be heavy. In proposed Mars missions I've seen, the major cost has been bringing the Mars ship and its fuel into orbit. The rockets used in the Mars mission could be conventional LH/LOX chemical rockets or NERVA-type nuclear rockets. Some sort of beam-powered (microwave or laser) electric rocket could also be practical, at least for the boost away from earth. The first missions to Mars will probably establish bases on or near Phobos and/or Deimos. These moons are likely to contain water and carbon compounds, and could be processed into air, food and fuel. Probably the cheapest way to get to Mars in the near term is by an Orion-type rocket. It could be built in orbit to reduce fallout, but this would again require cheap boosters to put its thousands of tonnes of mass into space. ET materials might be useful as shielding, or for structural material, if a nickel-iron asteroid could be snared. Water or carbon compounds from asteroids or the moons of Mars could be used as reaction mass in the shaped nuclear charges.
spock@iham1.UUCP (Ed Weiss) (12/10/85)
> A manned Mars trip should have low priority. The following items > are more important: > > (1) Cheaper transport to low earth orbit > (2) Reusable OTV's (robotic or remote controlled) > (3) Storage areas in LEO and GEO for parts & fuel for OTV's > (4) A LEO space station > (5) A GEO space station > (6) Visits to asteroids co-orbital with earth, if any exist > (7) A lunar base > (8) Visits to some Apollo/Amor asteroids > > It really makes little sense to visit Mars until we can do so > economically. This will require more infrastructure around earth > if we want to establish a base there at a reasonable cost. > The payback from asteroid visits is also likely to be higher, > if large amounts of mass can be returned to earth orbit. > Of course, there will be scientific benefits from a Mars mission, > but the results would be expensive, and more science could be done > on earth (in other fields) for the same money. > > ..... I think that we (the readers of this group and ME) spend too much time thinking of the practical and economical reasons for space related activities. There has been much discussion on how to justify our favorite program. What we need to concentrate on is not the REAL reasons why our program should be funded, but the reasons that will CAUSE our program to be funded. It seems to me that the best way to get funding is to appeal to the common American's sense of adventure. We need to capture their imaginations. THAT is how we are going to get funding. That is why the space station is important. It keeps space in the public's mind. (To get back to the subject line): A Mars project may be the way to get Americans as excited as they were for the Apollo project. If this happens then we may just get the funding we need. Funding for a Mars project may necessarily include many of the programs that we feel are necessary. The purpose of this article is not to say that we should stop thinking of GOOD reasons to justify space programs. What it is meant to say is that when we try to SELL our programs, we must use some political savvy. REMEMBER that the space budget is not fixed. Congress can vote us more money if they think it is politically good move. Sorry about my soapbox! -- Ed Weiss ihnp4!iham1!spock --> Live Long and Prosper <--
henry@utzoo.UUCP (Henry Spencer) (12/12/85)
> (To get back to the subject line): A Mars project may be the way to > get Americans as excited as they were for the Apollo project. If this > happens then we may just get the funding we need. Funding for a Mars > project may necessarily include many of the programs that we feel > are necessary. Unfortunately, the analogy to Apollo may be all too apt. What happens after the First Mars Expedition returns? How long before the budget starts getting cut back, back, back, on the grounds that "you've finished your job"? Take a tour of KSC, and be sure you look at the Saturn V lying on its side rusting: that was FLIGHT-READY HARDWARE, scheduled to launch Apollo 18 or 19. Or visit the Air & Space Museum in Washington: that's a real Skylab, intended to fly as a followon to the original; that's a real Lunar Module, meant for Apollo 18 I believe; that's a real Viking lander and orbiter, which many people wanted to fly as Viking 3. The people who are pushing for a Mars mission are setting us up for the same thing, on a much more massive scale. Yes, a Mars mission would require building many capabilities that would be useful for other things. And they might well get thrown away afterward. The US had *no* man-rated launch system in the half-decade between Apollo-Soyuz and STS-1! In 1970, the US could put a man on the moon; it can't today. We are *farther* from the moon now, in most ways, than we were in 1961: all the specialized hardware is gone, the tools and plans for building it are gone, and NASA has gotten older and more bureaucratized. (Does anyone really believe that today's NASA could mount a lunar mission within 8 years of being told to do it? The Space Station is a much simpler job, if you carefully avoid adding unnecessary frills like AI and other high-tech fads, and last I heard NASA had given up on having it operational within TEN years.) It's been pointed out recently that putting cargo into orbit with the shuttle is no cheaper, per kilo, than doing it with the Saturn V... and the Saturn V prices were based on a total production run of 15! How much cheaper would a modernized, volume-production Saturn be? We'll never know; that capability was thrown away. Apollo/Saturn technology could have sent a small manned expedition to an Earth-approaching asteroid at closest approach, given minor improvements in power and life-support to permit a longer stay in space. When Apollos 18 and 19 were scrubbed, all the major hardware needed for such a mission was *on* *hand*. Anybody want to guess when we get even an *unmanned* sample-return mission to an asteroid? Probably not in this century. The capability was thrown away. If you want a more modern example, a year or two ago it would have been relatively cheap to commit to assembling a backup Galileo, with an eye on sending it to Saturn if the original's Jupiter mission succeeded. This option is getting steadily more expensive as Galileo work teams disperse; the opportunity has probably been lost. Thrown away. Given the realities of funding, a major Mars mission is the last thing we need. Effort and funding *must* go towards building ongoing capabilities that will outlast individual projects. It is important to aim high when conceiving those capabilities, so that they will be *useful* for mounting exciting projects, but the capabilities must be justified on their own merits so we don't lose them afterwards! What capabilities do we need? First and most important, we need cheaper transport to low Earth orbit. Shuttle launch costs will dominate the operational price tag of almost everything else we do right now. Launch costs must come down, if only by the order of magnitude that the Shuttle was originally aimed at. (Many people think that a pretty unambitious goal; we could do better.) Second, we need an orbital staging point, where missions can be assembled. Life gets much simpler if an assembled system doesn't have to survive a noisy, bouncy Shuttle launch, or fold to fit the Shuttle cargo bay. The Space Station is a good approximation to this, although it could be done a good deal sooner and more cheaply than it actually will. Third, we need cryogenic propellant storage in orbit. This lets us mount high-energy missions without tight time constraints, and lets us use high- energy upper stages for space-assembled missions. We also need some minor related items of technology, like free-fall fuel transfer and a Centaur variant that can be fueled in space. The Centaur already has engine-restart capability, so in-space fueling at the Station gives us a good approximation to a reusable OTV. A hefty one. (Who cares if it's unnecessarily big for some missions? It can still fly them, and it doesn't have to be developed from scratch!) In the longer run, we should re-engine the Centaur, and examine larger Centaur variants with bigger tanks and/or more engines. Fourth, we need aerobraking technology. It's decidedly useful even for advanced OTVs working to GEO, and it's very important for lunar and planetary missions. Furthermore, it doesn't look that hard. It would be moderately useful to have partially-recycling life-support systems, to reduce the cost of manned operations in orbit, although Skylab demonstrated consumables-per-man-day figures low enough that the complexity may be hard to justify. Given the above, mounting a Mars mission, or an asteroid mission, or a lunar mission, or any number of other interesting things, becomes vastly easier. And all of these things are justifiable on their own (although aerobraking may be a marginal case), and will survive the success (!) of any particular mission.
karn@petrus.UUCP (Phil R. Karn) (12/13/85)
I keep hearing that the cost of launching something on the shuttle is $X/kg, and further that this cost is N times launching it on the Saturn V had we kept the production lines open. The exact values of X and N keep changing, but the argument is the same. Can someone present a DETAILED breakdown of the actual costs (not prices) for the two launchers? These figures should be broken down into three categories: 1. Up-front launcher development costs (research, development, testing). 2. Continuing operational costs that are relatively independent of the launch rate (JSC and KSC salaries, computer system maintenance contracts, electric bills, janitorial and landscaping services, that kind of thing). 3. Actual per-mission costs that are directly attributable to things consumed during each mission (fuel and other consumables, SRB refurbishment, ET and other one-shot components, short-term contract labor, etc). I think we have to present the costs broken down this way if we're to come up with a useful result. A single figure of $X/kg is bound to be misleading. Phil
franka@mmintl.UUCP (Frank Adams) (12/19/85)
In article <6218@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: >> (To get back to the subject line): A Mars project may be the way to >> get Americans as excited as they were for the Apollo project. If this >> happens then we may just get the funding we need. Funding for a Mars >> project may necessarily include many of the programs that we feel >> are necessary. > >Unfortunately, the analogy to Apollo may be all too apt. What happens >after the First Mars Expedition returns? How long before the budget >starts getting cut back, back, back, on the grounds that "you've finished >your job"? > >Yes, a Mars mission would require building many capabilities that would >be useful for other things. And they might well get thrown away afterward. The question is, would a Mars mission develop *enough* capabilities to make commercial use of space practical? If so, they wouldn't be thrown away; part of the problem after Apollo was that there wasn't any economic use for the hardware. I haven't seen any attempt to determine whether the Mars mission would produce sufficient technology. Part of the problem here is the imponder- ables. It is hard to estimate what an as-yet-undeveloped launch system will cost in actual operation -- particularly since cost/development time trade-offs are possible. One can do little more than guess at the economics of proposed space industries, so it is hard to tell what launch cost is required to make them profitable. One of the reasons I support the space station is that it changes the way subsequent missions get planned. Once you have a permanent operational facility in orbit, it makes sense to use it for such things. This leads to the development of space capabilities, not just launch capabilities. Frank Adams ihpn4!philabs!pwa-b!mmintl!franka Multimate International 52 Oakland Ave North E. Hartford, CT 06108
eder@ssc-vax.UUCP (Dani Eder) (12/23/85)
> I keep hearing that the cost of launching something on the shuttle is > $X/kg, and further that this cost is N times launching it on the Saturn > V had we kept the production lines open. The exact values of X and N > keep changing, but the argument is the same. > > Can someone present a DETAILED breakdown of the actual costs (not prices) > for the two launchers? These figures should be broken down into three > categories: > > 1. Up-front launcher development costs (research, development, testing). According to figures I got from the NASA History Office, the three stages of the Saturn V launch vehicle cost $5 billion each in today's (1986) dollars to develop. This excludes launch facility costs. The Space Shuttle program cost a total of $15 billion in total through the end of the 4th flight test, but that figure does not include inhertiance from the Saturn program. As an example, the Vehicle Assembly Building was modified for the Shuttle, but the modifications cost much less than building a new facility from scratch.> > 2. Continuing operational costs that are relatively independent of the > launch rate (JSC and KSC salaries, computer system maintenance contracts, > electric bills, janitorial and landscaping services, that kind of thing). > According to figures given to us by the Air Force for use in our current Space Transportation Architecture study, the Kennedy Space Center and Vanden- berg Air Force Base launch sites cost about $420 million per year each to operate, independant of launch rate. One Orbiter costs $2.4 billion dollars if ordered today. If you wait till next year to order one, the cost goes up, because all the subcontractors will have gone on to other things than making shuttles. > 3. Actual per-mission costs that are directly attributable to things > consumed during each mission (fuel and other consumables, SRB refurbishment, > ET and other one-shot components, short-term contract labor, etc). The cost of External Tanks depends on the production rate, as does many other components. An approximation for flight dependant costs is $1570 million for 24 flights/year +- 25 million per flight /year above and below 24 per year. As an aside, the liquid propellants cost $1.4 million per flight. According to my boss, who once was in charge of Saturn improvements at Boeing, the cost per flight of the Saturn was running $750 million at the height of the Apollo program. Since the payload of the Saturn V to low earth orbit is 240,000 lb, the marginal cost per lb was a little over $3000. When the Shuttle reaches 24 flights per year, the operating costs will be about $100 million per flight. Allowing for Orbiter life o f 100 flights, $24 million in vehicle depreciation should be added. Hence the true COST of the Shuttle per flight will be $125 million, or about $2000/lb.> > I think we have to present the costs broken down this way if we're to > come up with a useful result. A single figure of $X/kg is bound to be > misleading. Very true. One useful way to look at the comparison between Shuttle and Saturn is cost breakeven from development. The Shuttle costs $1000/lb less to operate than Saturn. To recoup the development cost of $15 billion requires the launch of 15 million pounds of payload, or about 225 flights. > > Phil Dani Eder/Advanced Space Transportation/Boeing/ssc-vax!eder