Orion and Falcon 9

[j05h]

Doc - Awesome, I've been looking for EDS mass numbers! Thanks, it bolsters my argument for LEO assembly and letting the corporations handle the Earth-LEO segment. <br /><br />Above I was asking about the masses of individual components, with and without propellant. The Altair number that I've read is 19t empty, including both modules, is that accurate? Are you saying the Altair descent module alone is actually 35t empty?<br /><br />The idea is to make each stage flyable on current rockets, then fuel them with infinitely divisible liquids flown on whatever the cheapest rocket is available to a propellant depot in LEO (or L1). Then fly these now-reusable components repeatedly. <br /><br />The three things keeping Orion off of Falcon 9: Falcon still in development but has flown, Orion's LAS, politics.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[docm]

I believe the numbers I read were wet, so yours could be close dry.<br /><br />OTOH Altair is a major moving target given the configuration is still under discussion while the EDS is more of a known quantity; there are only so many ways to configure a tin can. <div class="Discussion_UserSignature"> </div>

 

[j05h]

<i>> I believe the numbers I read were wet, so yours could be close dry. </i><br /><br />if true, all those dry masses are within existing rocket capabilities.<br /><br /><i>> OTOH Altair is a major moving target given the configuration is still under discussion while the EDS is more of a known quantity; there are only so many ways to configure a tin can.</i><br /><br />I really enjoyed the several Lockheed concepts based around the Centaur and RL10, both for TLI and landing. Especially liked the dual-axis horizontal lander, good visibility and shoulder-height equipment when unloading. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>This scenario may or may not happen, but ... I was pointing out that once you have a LEO-capable capsule, like Soyuz or Shenzou, you can organize more ambitious missions by LEO staging.<br />That is exactly the plan for the 100-million Soyuz lunar flyby idea, and the concept has been demonstrated before. It also scales.<p><hr /></p></p></blockquote><br />Like I said before, once that money has left NASA's budget, it's gone forever. NASA isn't banking on what it hopes Congress <i>might</i> do, but what it knows Congress <i>will</i> do. There are many forces within Congress that want to shut down VSE because they view that money as money that could be going to their pet pork. NASA is trying to put as much momentum behind the project while Bush is in office because NASA knows that once Bush leaves office, support for VSE will dry up. The only reason that the Republicans in Congress support VSE is because Bush supports it. If the Constellation program has enough momentum behind it before Bush leaves office, it may be too hard to kill.<br /><br />Also note that the Soyuz lunar flyby, the money for that is not coming from the Russian government, but from private investors. (assuming that that whole thing takes off) <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>There's a problem with this scenario, Congress not the president would do that. Not to say that the President wouldn't chime in. Congress would tell NASA to find a different solution and wouldn't dictate to NASA what that solution would be.<p><hr /></p></p></blockquote><br />Yes, this is true, but Congress can whittle down the budget for the program enough that NASA has no option but to make Orion an LEO only spacecraft. Make no mistake, NASA's number one priority is to replace the Shuttle, the larger goals of VSE are secondary. If all NASA can afford is a near-term replacement for the Shuttle, that is all that they will build. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[no_way]

<blockquote><font class="small">In reply to:</font><hr /><p>liquids flown on whatever the cheapest rocket is available to a propellant depot in LEO (or L1)<p><hr /></p></p></blockquote><br />A lot of cheap rockets cant get to L1. I have been willing to start a discussion about what an ideal LEO staging orbit would be for lunar sorties, considering all the active and near-term launchers on the market over the world, over active launch sites ( considering that Soyuz will be launching from Korou soon as well )<br /><br />Also what useful payload size categories would it leave us with. I.e. whats the lowest common denominator for 20mT to LEO class rockets ( Proton, Ariane 5, CZ-5s, EELVs, Angara ) at what orbit, leaving margin for payload adapters etc ? It may turn out to be like 18mT instead.<br /><br />Then for really cheap launchers like Dnepr you would want to make absolutely sure that your orbit is where your accessory mass ( fuel tanking, adapters etc) does not cut too much into useful propellant load mass. <br /><br />But again, having too low orbit will have considerable reboost requirement due to atmospheric drag.

 

[gunsandrockets]

<I have been willing to start a discussion about what an ideal LEO staging orbit would be for lunar sorties, considering all the active and near-term launchers on the market over the world, over active launch sites ( considering that Soyuz will be launching from Korou soon as well )><br /><br />Because the moons orbital inclination is close to zero, the ideal LEO depot from an efficiency point of view would have a similar inclination. Launches from the equatorial region of Earth, of which there are very few active bases currently, also maximizes payload to LEO.<br /><br />But I believe your quesition is -- what orbit to place your refuelling depot into, that would grant all the spacefaring nations easiest access? I have heard that payload suffers more when a spacecraft is launched into a LEO with an inclination lower than the launch lattitude than it is to send the spacecraft into LEO with a greater inclination. This is the main reason why the ISS has an orbital inclination matched to the high Russian launch lattitude rather than the lower lattitude of Florida. So if you want all nations to supply a LEO depot with the smallest penalty you are talking about an ISS style high inclination orbit.<br /><br />Another possibility is to place your depot at the EML-1 point. A reusable solar-electric-propulsion (SEP) tug could rendezvous in LEO with each launch vehicle and then boost each payload up to supply the EML-1 depot.<br /><br />The greatest problem with any propellant depot scheme is long term storage of the propellant in space. High ISP propellants like liquid hydrogen take lots of volume to store and require refrigeration to minimize boiloff losses. And the extreme thermal cycling that handling transfers of hydrogen that the depot would be subject to would increase the chance of mechanical failure and reduce the operational lifespan of the depot.<br /><br />On the other hand storage and transfer of non-cryogenic propellants seems quite practical, and the experi

 

[j05h]

<i>> Another possibility is to place your depot at the EML-1 point. A reusable solar-electric-propulsion (SEP) tug could rendezvous in LEO with each launch vehicle and then boost each payload up to supply the EML-1 depot. </i><br /><br />This is roughly the approach I favor, whether the tugs are chemical rockets or SEP. Payloads are placed in any Low orbit, met by a tug and brought to the EML1 depot. This has the advantage of being able to consolidate payloads from any launch pad on Earth, regardless of inclination, then dispatch them to the Moon, Mars and Beyond(tm). <br /><br />The L1 Depot can store propellant, outfit outbound craft, refuel tugs, provide a really nice hotel location and provide complimentary science activities. <br /><br />Ammonia-fuelled NTRs would rock, but don't bet on their implementation. The best thing on the horizon is VASIMR.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>Because the moons orbital inclination is close to zero...<p><hr /></p></p></blockquote><br />???<br />Where did you hear that? The Moon's orbital inclination varies between 18.29º and 28.58º. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[thereiwas]

I think he meant relative to the Earth's equator, not the solar orbit.

 

[PistolPete]

That is relative to the Earth's equator. The Moon's inclination is 5.145° in reference to the ecliptic. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[halman]

spacer01,<br /><br />Probably the only reason that the Falcon 9 will not be able to lift the Orion is because several billion dollars a year is not being spent on its development. The Ares launch vehicles will soak up most of the 8 billion a year that the U.S. is spending currently on shuttle operations. With that kind of funding, failure only means delays of a few months, maybe a year, before a new, revised version will be ready. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[gunsandrockets]

<The best thing on the horizon is VASIMR.><br /><br />In my opinion VASIMR is more hype than hope. <br /><br />

 

[gunsandrockets]

<br /><br />Yep, you're right. When I was doing some research some months ago I confused the celestial with the ecliptic. Oops!<br /><br />Therefore in terms of lunar missions that makes Florida better than equatorial launch locations.

 

[PistolPete]

It's about the same either way. Although, an equatorial launch site might have more Lunar launch windows. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[j05h]

In what ways is VASIMR hype? The biggest stumbling block I'm aware of is the power source. <br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

From the numbers that I have seen VASIMR is no more efficient at generating thrust than other electric rocket engines already in use.<br /><br />The truly unique thing about VASIMR is it's ability to operate over a very large range of ISP vs thrust. But even here the VASIMR is not as unique as advertised since other electric engines are also capable of operating over a variable range of ISP vs thrust.<br /><br />If you come up with a power source for VASIMR, the same power source could also be used for any of the other electric engines. Power is the true limiter on all electric engines.

 

[docm]

Yes, the efficiency of VASIMR is in the 87% range and traditional ion engines are in the 90's. That said a Prius is more efficient than a Rover, but which would you rather drive across Africa in? <br /><br />The bottom line is that even at this stage of development a VASIMR can produce roughly 1 N of thrust per 100 kW of power and ion drives could be out-pushed by a good sized fart.<br /><br />That said there are other good candidates, MPD being just one. The problem is the same as with ion drives: they all have electrodes that can wear badly over time. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

I think some of the high-powered Hall effect thrusters under development have the greatest near term potential for jobs like reusable tugs or manned interplanetary transfer vehicles.

 

[windnwar]

Although I know it'll instantly have enviro critics, seems to me the best source of power for the tug would be a nuclear power source running any of the plasma/ion engine setups, very small reactor supplying all the electrical power, it'd eliminate the issue of having the batteries to store it, and allow you to use a propellant easy to transport while getting the most miles per gallon basically out of the fuel. <br /><br />The reactor could be in one section, with a detachable plasma/ion engine section attached to it. That way, as the engines wear out, you can just swap out the engines, all your propellant tanks and reactor would continue to be reused. It'd never be operated in LEO at all, just from the L1 point to lunar orbit and back. Built like that, as the engines improve, so long as they don't exceed the reactors power output, swapping out the engine section will allow it to have greater performance and the reactor life should be quite long. Later it could allow the tugs to possibly go to there locations such as asteroids etc. Simply use the best performing electrical propulsion you can. <br /><br />Maybe i'm thinking crazy though. <div class="Discussion_UserSignature"> <p> </p><p><font size="2" color="#0000ff">""Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein"</font></p> </div>

 

[no_way]

<blockquote><font class="small">In reply to:</font><hr /><p>But I believe your quesition is -- what orbit to place your refuelling depot into, that would grant all the spacefaring nations easiest access? <p><hr /></p></p></blockquote><br />Not precisely. My question is, that given the launch vehicles in opeartion now and in near future, worldwide, i.e. space launch assets that we have, what would be the optimal orbit to place a fuel depot so we dont leave out any of the launchers that could significantly contribute, or dont penalize their payload capacity too much.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Another possibility is to place your depot at the EML-1 point. A reusable solar-electric-propulsion (SEP) tug could rendezvous in LEO with each launch vehicle and then boost each payload up to supply the EML-1 depot.<p><hr /></p></p></blockquote><br />You are putting significant risk and tech development factor into the project immediately with this approach, and also from operational standpoint either you would have to have lots of tugs or just accept the fact that they can make the trip every so often.<br /><br />

 

[docm]

<font color="yellow">Maybe i'm thinking crazy though.</font><br /><br />Actually IMO you're spot on. There are already designs for small (and not so small) space reactors that would be perfect for VASIMR and the other plasma thrusters, and space tugs is just the beginning of how they could be used. <br /><br />Sure, solar would be fine for small jobs like ISS repositioning, but for real cargo hauling something with more oomph is in order. <div class="Discussion_UserSignature"> </div>

 

[josh_simonson]

For near-earth operations, solar is king. Once out of LEO, solar provides power almost continuously and solar also avoids the perceived danger of accidental re-entry. It won't sit well with people to have a nuclear tug bopping back and forth between LEO and LL1.<br /><br />Nuclear power sources shine best in missions farther out from earth orbit because the energy from the sun goes down, which makes solar less attractive.<br /><br />For an LEO to LL1 tug, the only effect the size of the power source has is how long it takes to make the trip. As long as people or perishable fuel aren't on board, we shouldn't really worry if it takes 1 week or 6 months. Since the plan at the moment is only to have two missions per year, a 6 month round trip time would be adequate for a single tug.