Redundancy -- NASA needs two different CEVs and boosters

gunsandrockets · May 30, 2005

Right now there is speculation that the new NASA administrator Griffin will select a single CEV design relatively soon and develop a Shuttle derived launch vehicle for launching the CEV into space. Whether this is true or not, I will try to make the case for doing something very different. First a little background. Back when NASA went with the Space Shuttle Transportation System (STS), NASA and the USAF agreed to use the STS for all lift needs in an effort reduce STS costs by increasing the flight rates. When STS Challenger blew up in 1986, putting all the eggs into one basket had left NASA and the USAF with a difficult situation. USAF withdrew from the STS program leaving NASA to absorb the extra costs, and both NASA and the USAF had to scramble to use other boosters than the STS. The USAF learning from the STS experience started the EELV program to develop and produce two different launch vehicles. This way if either booster was grounded there would still be a backup to launch vital national defense missions. Two companies producing rockets at the same time would also hopefully create competitive pressures that would reduce costs. The extra development costs of producing two vehicles was accepted in the hopes the advantages would outweigh the costs. Also during the 1970's the USAF found itself getting priced out of the fighter business with the projected costs of the F-15 Eagle program which was intended to replace the fleet of USAF F-4 Phantoms and F-106 Delta Darts. So the cheaper F-16 was purchased in addition to the F-15 to fill out the fighter ranks. This concept of Hi/Low mix of some high end expensive units supplemented by larger numbers of cheaper units is a principle still followed today by the USAF and other American Services for some aircraft and other programs. Today, with the STS grounded after the Columbia disaster, NASA is again stuck with no way to get men to space short of paying the Russians

spacester · May 30, 2005

It seems to me that the best way to supply the redundancy we certainly need is simple in principle. 1. Have the gummint develop its best combination of vehicles to do everything we want to do. 2. Encourage, support, enable, cajole and subsidize Private Enterprise to develop a combination of vehicles to do everything we want to do. 3. If a particular vehicle fails, use the capabilities from the other approach. Since the private vehicles will almost certainly operate more cheaply than their gummint counterparts, over time the gummint vehicles will be used only for those things the gummint is not comfortable doing with private stuff. But since the gummint cannot just wait for a private system to come into being, it's OK that the gummint vehicles operate at a higher cost. <div class="Discussion_UserSignature"> </div>

najab · May 31, 2005

The CEV is supposed to be compatible with multiple launch systems.

smradoch · May 31, 2005

What about Grumman Northrop CEV as primary vehicle, which can be launched on SDV (all in one to Moon), Atlas, Delta (only to LEO). And t/Space CVX as alternative to LEO. Lockheed Martin or winged CEV can be built when there will be real reason to do that (fast turnaround and reusable launcher). But even only with one type of capsule it's quite safe - you will have more boosters at your disposal and safer (semi)expendable design - nothing like STS.

gladiator1332 · May 31, 2005

Ia gree with you entirely. While the Lockheed design is the more attractive design, it really is not needed. Yes it has lower G-loads on re entry. Yes it can glide in close to home. However, we don't need the fast turnaround yet. For the first few years and maybe even decades of lunar exploration, NASA will not be launching lunar missions every week. We're lucky if they even launch one a month. So I say they launch the Grumman CEV umanned on a SDV. This will have your CEV and the stage for the TLI burn and whatnot. The crew would follow in the T/Space CXV, air launched. Actually why not go with the T/Space CEV as well? Its shape has come up in other studies before. T/Space would probably figure out a way to build it for much less. And you wouldn't need to build a lunar lander, as it already has the capability to land on the Moon. Either way, a SDV is going to be needed. I do not think NASA will go with an EELV. In 2010, the Shuttle program is shut down, the orbiters go to museums thorughout the country. All the people involved with the shuttle program will be out of the job. The EELVs will still be launching, so their workers will still have a job. So to keep the shuttle workforce on the job, NASA will most likely give them something to do with a SDV.

gunsandrockets · May 31, 2005

"What about Grumman Northrop CEV as primary vehicle, which can be launched on SDV (all in one to Moon), Atlas, Delta (only to LEO). And t/Space CVX as alternative to LEO." I would have no problem with that. But as has been noted by others, Griffin seems to be leaning towards something even bigger than the Lockheed CEV. By that reckoning the Lockheed CEV could end up as the smaller alternative! "But even only with one type of capsule it's quite safe " I have to disagree. I really think NASA needs a backup if/when problems ground the primary manned spaceship.

gunsandrockets · Jun 1, 2005

>>>Two points really: Access to LEO, and beyond. LEO needs, NEEDS more than one path, as has been proven with Shuttle/Soyuz. No common failure point, booster or spacecraft, can be allowed to compromise that access. "Beyond" may, or may not, be more tolerant, depending on mission profile. US/CEV and Euro/Russian Klipper seems a good match to provide that.<<< I agree in part and differ in part. Because of the investment in the ISS, LEO access is more vital, at least for now. 15 years from now we might find just as much invested in assests beyond LEO. As for other spacefaring nations, such as ESA use of Kliper, I'm all for it. But I think America must not depend on other nations to guarantee manned access to space. After all, that's exactly the situation America faces today with the Soyuz filling in for the STS. One alternative though, would be for NASA to cooperate with ESA, Japan and Russia and make the Kliper the first worldwide spacecraft with all parties allowed to produce and operate the vehicle individually. Then Kliper could really provide backup to a second purely American CEV.

acid_frost · Jun 1, 2005

Please be patient iam not as space savvy as you all, so bare with me. Iam kinda of new and iam trying to learn the lingo! LOL, its all good though I love space. I like the Lockheed Martin CEV design, though I think we need to move away from the reliability of one in all to the moon concept. I think I read on the forums that there is some type of plan that Griffin likes based on two vehicles that do two different things so that we don’t rely sole on one vehicle which has crippled the Space program currently. What I suggest is that we have the CEV, and have redundant system for launch on that CEV type vehicle. Also I would have some type of transfer vehicles for going to the moon from the space station. The reason I say this is because it seems the problem is bring an all in one vehicle home is something that we have a problem with and it would reduce the possibility of losing our one vehicle concept to getting to the space station and to the moon. We need to learn from our mistakes and go back to the basics and then some. If this has been talked about iam sorry. Acid

gunsandrockets · Jun 1, 2005

"If this has been talked about iam sorry." No need to apologize. Welcome to the forums. "I like the Lockheed Martin CEV design, though I think we need to move away from the reliability of one in all to the moon concept. I think I read on the forums that there is some type of plan that Griffin likes based on two vehicles that do two different things so that we don’t rely sole on one vehicle which has crippled the Space program currently." It's hard to predict right now what NASA will do. But we can make pretty good guesses based on paperwork NASA has already released and various statements that the new NASA administrator has said recently. Recent statements from Griffin and other news suggest, but only suggest, NASA will go with a 30 tonnes or more large Crew Exploration Vehicle (CEV) launched by a new Heavy Lift Vehicle (HLV) derived from the Shuttle Transportation System (STS). This CEV might use a flight architecture of direct flight to the Moon and direct return to Earth. That is a single spacecraft that would land on the Moon, and then launch again straight back towards Earth, without docking with or employing any other separate vehicles. Everything I have just said in this paragraph is highly speculative. We just don't know for sure yet. On the othe hand, the paperwork NASA has released so far, and upon which both the Lockheed Martin team and the Boeing Northrop Grumman team have submitted official bids to NASA, provide a more clear picture of NASA plans. And this plan is very different from a single large CEV launched by a HLV. It resembles in some ways the Soviet plans for reaching the Moon in the 1960's during the Space Race with the United States. This plan employs both Earth Orbit Rendezvous (EOR) and Lunar Orbit Rendezvous (LOR). LOR is what the Apollo program used by having a separate spacecraft, the Lunar Module (LM), which would land on the moon while the Apollo Command and Service Module

grooble · Jun 1, 2005

"No need to apologize. Welcome to the forums. " He's been a member longer than you. boooOOOY! <img src="/images/icons/laugh.gif" />

nacnud · Jun 1, 2005

Sadly, the International Space Station (ISS) is in a very bad orbit to use as a base of operations for travelling to the Moon or other places in the solar system. Not really, I don’t think there is that much difference in delta v from the ISS inclination than from any other. IIRC then the energy differences from different inclinations come in the earth to LEO stage rather than the LEO to moon stage.

gunsandrockets · Jun 1, 2005

"Not really, I don’t think there is that much difference in delta v from the ISS inclination than from any other. IIRC then the energy differences from different inclinations come in the earth to LEO stage rather than the LEO to moon stage." I believe you are incorrect. Changes in orbital inclination take energy whether it is in LEO or beyond LEO. Take the Moon for example... " the lunar orbital plane thus sees its inclination with respect to the Earth's equator (itself inclined 23.45° to the ecliptic) vary between 23.45° + 5.15° = 28.60° and 23.45° - 5.15° = 18.30°" The Moon's orbital plane (28 to 18 degrees), is way off from the orbital plane of the ISS (51 degrees). My poor math skills are not up to figuring out the difference in delta vee between 51 degrees and 28 degrees, but the penality is significant. [Is there an orbital mechanics specialist in the house?

] I do know the difference between LEO and TLI is about 3.4 km/s, assuming the LEO is in the correct orbital plane. LEO by itself is about 7.8 km/s, so the bulk of the delta vee is just from assuming LEO. Think of it this way, the Moon is in LEO + 3.4 km/s! If your spacecraft LEO is inclined way off from the Moon's orbit, you have to match the difference in inclination before adding the extra 3.4 km/s to get the rest of the way to the moon.

acid_frost · Jun 1, 2005

gunsandrockets, Thank you for the warm welcome, and its ok you aren’t talking down I want to know the up and up and the savvy talk also!! LOL. “Sadly, the International Space Station (ISS) is in a very bad orbit to use as a base of operations for traveling to the Moon or other places in the solar system.” My understanding is that every time the shuttle would dock with the station it was to nug it further and further into a more stable orbit to prevent the possibility of losing orbit! Iam not sure if that is even possible but I would think they should place it somehow in a further orbit to last a while with all this work going into it. Besides that I think that it would be a rather sham to not utilize the ISS as a launching platform. It would simple be a waste in not utilizing the ISS for such explorations. Acidrain

gunsandrockets · Jun 1, 2005

"My understanding is that every time the shuttle would dock with the station it was to nug it further and further into a more stable orbit to prevent the possibility of losing orbit!" Partly true. The ISS in it's LEO is subject to tiny amounts of drag from the fringes of the atmosphere. Without periodic re-boosting the ISS orbit would eventually lower enough to burn up in the atmosphere. About once per year the ISS must also shift it's orbit slightly to avoid possible collisions with orbital space debris. http://www.shuttlepresskit.com/ISS_OVR/assembly1_overview.htm As I understand it the ISS uses about 7 tons of fuel per year for stationkeeping and orbital adustments. This fuel is delivered by routine flights of the Russian unmanned Progress spacecraft. " Iam not sure if that is even possible but I would think they should place it somehow in a further orbit to last a while with all this work going into it. Besides that I think that it would be a rather sham to not utilize the ISS as a launching platform. It would simple be a waste in not utilizing the ISS for such explorations." It is a shame. The basic design of the ISS was compromised almost from the beginning. The main goal of the station changed from utility to multi-national involvement. The ISS should have been paid for by the U.S. State Department instead of NASA! Major compromises and changes in the design of the ISS were made to accomodate Russian flight needs and incorporate Russian designed elements. The 51 degree orbit of the ISS is easier to reach for Russian spacecraft. Main ISS modules were leftover components from the Russian MIR spacestation program. In a way the ISS isn't much more than a Russian MIR 2! Changing the ISS into a very different orbit could be done, but the cost would be huge. Once finished the ISS will be enormous. The fu

acid_frost · Jun 1, 2005

gunsandrockets, Thank you for the explanation. Iam also wondering, the ISS is to have a life of what 20years? If so and the effort and hassle to put this together wouldn’t it be logical place it in a higher orbit for the life that we hope that the ISS will have? Once completed their needs to talk about moving further out into a more stable orbit or what’s the point in having this ISS? We are really getting off topic so ill get back on. As for the CEV I like your explanation to the different approaches that Boeing and Lockheed are taking but what really gets me and just blows me away is the gap issue, which I find very just odd. I mean we have the plans from the old Apollo missions and we have better technology in providing launch capabilities and other technologies that we don’t know about to makes this a lot faster and safe at the same. The reason I say this is because I work for a defense contractor, (which I wont mention due to the nature or it, and my job) and Ill tell you that their technologies that we have that public doesn’t now about. It just blows me away in regards to why we aren’t further into space and on Mars and the Moon already. So as to a vehicle for LEO to the Moon, I don’t understand why we cant build something that is attached to the ISS such as a space craft for going to and from the moon, with another vehicle waiting in the Moons orbit which makes, having more than one vehicle makes it safe. So that where iam at, so if iam repeating iam sorry. Acidrain

radarredux · Jun 1, 2005

> The ISS in it's LEO is subject to tiny amounts of drag from the fringes of the atmosphere. Without periodic re-boosting the ISS orbit would eventually lower enough to burn up in the atmosphere./i> Just an interesting factoid. Found a history of ISS's altitude at the following web site (I'll try to attach the graphic too): http://www.hq.nasa.gov/osf/station/viewing/history.html

gunsandrockets · Jun 2, 2005

" It is true that a plane change to a spacecraft in Earth orbit is expensive in the use of delta V however the further you are from the Earth the Delta V required to d a plane change is much less. " The cost to plane change may be lower the higher an orbit is, but there is still a cost, no? How much is that cost? Here is an interesting tidbit I found... http://zebu.uoregon.edu/~js/space/lectures/lec06.html "In recent years modified versions of the GTO orbit have been used. A supersynchronous orbit is one where the apogee is significantly greater than geosynchronous altitude. Why send the payload higher than the target orbit altitude? The reason is because the payload still has to adjust its inclination from the launch inclination (anything from 5 to 51) to 0. This maneuver is very expensive in terms of energy, much more so than an in plane change of orbital altitude. The energy required to do this maneuver decreases with orbital altitude, so it requires less fuel to perform this plane change at high altitude (e.g.. 60,000 or 70,000 km) and then descend to a geostationary orbit rather than do the plane change at geostationary height." So if I understand this text correctly, plane changes are so expensive that to reach a particular target orbit, it's cheaper to send an object to an even higher orbit before paying for the plane change, then it is to change planes at the correct orbit altitude. No matter which technique is used, plane changes sound awfully expensive to me.

gunsandrockets · Jun 2, 2005

"The CEV is supposed to be compatible with multiple launch systems" Maybe. If the Griffin talk of a CEV greater than 30 metric tons has any force behind it, only a SDV or similiar nonexistant HLV could lift that much weight to LEO.

spacester · Jun 2, 2005

Here is a formula that has been floating around on the web for years. It can be seen to be a form of the vis-viva equation: Change in velocity required for a plane change of angle phi in a circular orbit: delta V = 2 sqrt(GM/r) sin (phi/2) This shows that the dV is inversly proportional to the square root of the orbital radius. NOTE that this is for circular orbits, so what this is telling you is the change in orbital energy between two circular orbits of the same radius but on different planes. I've tried like heck to verify (although not recently), without success, that it also applies to an elliptical orbit where the dV impulse is applied at apogee = r Nevertheless, I believe it can correctly be applied as such. IOW it appears to be a simple matter of plugging in the orbital radius at the apogee burn, the plane change angle, and the planet's GM value. (Note that GM = 398600.44 km^3 s^-2 for Earth) (The reasoning behind thinking this is valid is not easy to explain . . . ) <div class="Discussion_UserSignature"> </div>

gunsandrockets · Jun 2, 2005

"He's been a member longer than you. boooOOOY! " http://members.fortunecity.com/modelman51/phantasm1agnusbio.htm

smradoch · Jun 2, 2005

I hope that a part of CEV can be used for LEO (ISS) only. That part cann't wight 30t. Such vehicle couldn't pay off. Kliper will be for 6 and weight much less. CEV for Lunar mission can be heavier but it wouldn't be launched when there is problem with launch vehicle.

mrmorris · Jun 2, 2005

"It so cheap that even if they deliever on half of the promises it will still be more economically efficent then any other space vehicle developed in the last 30 years. " Depends on what exactly the half is that they deliver on... If it works but they missed out on cost projections by half (i.e. it's twice as expensive as they project) -- then you've made a true statement. If it only halfway works (i.e. they find a 'sticking point' that simply can't be resolved in their design) -- then it matters not how little got spent on the R&D, a non-functional vehicle isn't economically efficient by any standard.

gunsandrockets · Jun 10, 2005

"Just an interesting factoid. Found a history of ISS's altitude at the following web site (I'll try to attach the graphic too): " Yikes! varying by 70 km!

mrmorris · Jun 10, 2005

"Obviously your not going to drive a car with two wheels. " In retrospect -- with the two-wheeled car sitting in front of you -- yes, it's obvious. However, when the revolutionary auto designer comes up to you and offers to build a wonderful new car for you and it'll only cost $500 to build and he shows you a great presentation of its multitude of features and an animated video that shows (from one side only) the car being put through its paces... it's not obvious that the car only has two wheels. What I was trying to get across is that there are so many revolutionary things about the CXV that there are so many potential failure points as to make the concept very uncertain. I'm not claiming that they can't do it -- just that they haven't, and there's no guarantee that they can.

nacnud · Jun 10, 2005

I thought the reason, well the designed reason, for the variablity of the orbit was to maximize the amount of time that microgravity could be sustained in order for reasurch. Obviously this isn't the case at the moment as there are hardly any man hours left for reasurch. From esa Human Spaceflight webpages Example Operational Modes Timeline The planning of ISS operations will ensure that the 30-day requirement for microgravity is fully met. An example of such a planning is shown in the figure, where rendezvous, reboost, microgravity mode and maintenance activities are performed interspersed with each other. A visiting vehicle will rendezvous with the ISS when the orbit is relatively low, and during the next 15 days, the crew will perform the necessary re-supply operations. During the following 10 days the reboost operations will be performed to raise the altitude of the ISS, after which the ISS will "coast" for a period of 80 days. Two 30-day microgravity periods can occur within this timeframe, together with two 10-day maintenance blocks.

Redundancy -- NASA needs two different CEVs and boosters

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