Post central for information on CEV - iformation station for the spacecraft

RobS · 2004-01-22 09:01:38

"We're not going to start with a clean sheet of paper," O'Keefe said of shifting its focus from the Orbital Space Plane to the Crew Exploration Vehicle. "It's not a matter of Orbital Space Plane being cancelled, it's a question of how do we evolve it to the Crew Exploration Vehicle."

This is in the article on Space.com about how NASA's budget would have shrunk if not for the new Bush plan.

-- RobS

RobS · 2004-01-22 09:15:56

Regarding using the ERV cabin as the CRV, that would work for the moon in particular; in fact, it might have the ability to ferry more than four people to the moon, since the ERV's internal volume is designed to be enough for four people to live for six months, and four people don't need that much for a few days. However:

1. The ERV will also require a launch escape system, and I don't know how much that masses. It may add so much mass, the ERV couldn't be lifted to ISS.

2. The ERV plus launch system would be way too roomy to send astronauts to ISS. The space could accommodate cargo, but the EELV doesn't have the lift to carry an ERV plus cargo to ISS.

3. The ERV's life support system probably should be redesigned for earth orbit use, since most of the time you don't need a six-month life support capacity.

It seems more likely that the CRV will be like Soyuz and Shenzhou: modular, with a capsule to return people to Earth and a support and living module for the crew to live in. Such a vehicle also has a built-in lifeboat if the living module has a problem. Other advantages to this system:

1. For hops to ISS, you send the capsule with the crew and replace the living module with cargo, since they can manage in a capsule for 24 to 48 hours.

2. For the moon, you want the capsule and living module to mass less than about 12 to 14 tonnes, so that a separate EELV launch can put a 25-tonne stage in orbit to which they would dock to fly to the moon.

3. For Mars, you'd want a larger living module, because you'd go stir crazy living for six months in the small space adequate for a three-day moon flight. Ideally, you'd put a heat shield on the living module so the combination can aerobrake into Mars orbit and you'd leave the living module up there and fly to the surface in the capsule.

clark · 2004-01-22 11:01:56

Perhaps we should take a refresher course on the technology being demonstrated on the X-37....

[http://www.nytimes.com/2004/01/22/science/22NASA.html]NY times article: Bush Wants Bigger NASA Budget, Official Says

At a breakfast meeting with reporters, Mr. O'Keefe said the agency would realize $6 billion more by scrapping the orbital space plane, a craft that was supposed to replace the space shuttle, and diverting money from other NASA programs.
Another craft being developed, the reusable X-37 cargo vehicle, will continue at least to the test-flight phase, in which it will be dropped from an airplane, he said. The X-37, a six-ton winged vehicle that is 27.5 feet long, was to have been sent into orbit in 2003 but has faced a variety of obstacles. One of its goals is to test new heat-shielding materials.
Mr. O'Keefe would not elaborate on details of the new objectives, saying that to do so would cut off some areas of thinking. Since the loss of the shuttle Columbia last Feb. 1, he said, NASA has learned to question every assumption and not to cut off areas of discussion.
Mr. O'Keefe said the changes his agency had been forced to confront since the accident would be helpful in designing a new spacecraft to carry astronauts. ``In many ways we're probably in a better position right now than we might have been otherwise,'' he said. ``Make no mistake, the accident really, really shook the foundation of this agency. It forced us to think about these absolutes, things that we take as fact.''

clark · 2004-01-22 11:16:04

Okay Bill, Aluminum is bad. Very, very, bad.

Just a quick question, what spacecraft uses aluminum as a protective layer today?

Another link...

This one is to a transcript of O'Keefe in a Q&A session with reporters after Bush's space policy pronouncement.

It's rather long, but there are several bits on the CEV (among other goodies!). It's PDF, so I can't copy and past the relvant parts, but look at the top of Page 4, and you will find some info directly related to CEV.

[http://www.nasa.gov/pdf/54876main_okeef … 012004.pdf]O'Keefe transcript with reporters

Bill White · 2004-01-22 11:25:06

Note: I have deleted my "daughter particle" radiation comments and started a new thread. Sorry for any apparent hi-jacking of the current conversation.

clark · 2004-01-22 11:27:30

Bill, there is absolutely nothing about me that is even remotely proffessional.

Edit: But enough about me, how about this radiation issue...

[http://www.spacedaily.com/news/radiation-04a.html]Fire Away, Sun and Stars We've Got Radiation Shielding Onboard

The team is examining new shielding materials that not only block and/or fragment more radiation than aluminum -- the material currently used to build most spacecraft structures -- but also are lighter than aluminum. Spacecraft designers have to be able to shape shielding materials to make various parts of the spacecraft. The material must protect the crew from radiation, and it must also deflect dangerous micrometeoroids. The shielding must be durable and long lasting -- able to stand up to the harsh space environment.
Polyethylene is a good shielding material because it has high hydrogen content, and hydrogen atoms are good at absorbing and dispersing radiation. In fact, researchers have been studying the use of polyethylene as a shielding material for some time. One of several novel material developments that the team is testing is reinforced polyethylene. Raj Kaul, a scientist in the Marshall Center's Engineering Directorate, previously has worked with this material on protective armor for helicopters.
"Since it is a ballistic shield, it also deflects micrometeorites," Kaul says. "Since it's a fabric, it can be draped around molds and shaped into specific spacecraft components."
Kaul makes bricks of the material by cutting the fabric and layering 200 to 300 pieces in a brick-shaped mold in his laboratory at the Marshall center. He then uses a vacuum pump to remove air and prevent bubbles in the material, which would reduce its strength. The material is "cooked" in a special oven called an autoclave, which heats the material slowly to 200 degrees Fahrenheit while putting it under pressure of 100 pounds per square inch using nitrogen gas. The combination of heat and pressure causes the chemical reaction that bonds the layers together to form a brick weighing about half as much as a similar piece of aluminum.
"Fiber is the secret of the material's strength, " explains Kaul. "Bulk materials usually are not as strong because they are more likely to have defects. A spider's web is strong because it is made of individual fibers."
But building a better shield is only half the answer to the problem. If too much shielding material is used, the spacecraft becomes way too heavy to get off the ground. So NASA is also working on medical countermeasures that limit the effects of radiation on space crews.
The Space Radiation Health Project at NASA's Johnson Space Center in Houston involves scientists nationwide at universities and medical centers. They are investigating how space radiation damages cells and tissues such as the eyes, brain and internal organs. This information can be used to develop effective medical treatments that limit damage done by radiation exposure.

Bill White · 2004-01-23 12:22:23

Boeing releases interesting [http://boeingmedia.com/photoreleases/index.cfm]CEV information.

Note the inflatable habitats for human occupation.

Edit: But enough about me, how about this radiation issue...

Okay, okay, CEV is looking better and better. :;):

Now, how many Delta IV launches will be needed to assemble this [http://boeingmedia.com/images/one.cfm?i … &release=t]spacecraft?

clark · 2004-01-23 12:38:21

The Boeing Vehicle?

Looks to be 4. (2 for the lunar propulsion, one for the resource module, one for the hab)

Bill White · 2004-01-23 12:55:54

The Boeing Vehicle?
Looks to be 4. (2 for the lunar propulsion, one for the resource module, one for the hab)

Plus 1 more for a lander, right?

clark · 2004-01-23 17:19:13

Perhaps... unles the lander is somehow folded into the resource module section.

Hmmm, perhaps they're thinking that the trans-lunar set-up would take the astronauts to the moon, to meet up with a pre-landed habitat module. You can see their design for a habitat module, which refrences a derivitive resource module with the lunar landing pads beneath it. This might imply that the resource module on the trans-lunar set-up would contain similar lunar landing pads- the command module sits on top, which would be the ride home after the mission...

Perhaps apply a little of the Mars direct plan by prepositioning supplies on the moon for a manned landing. Dry run for any eventual Mars Direct plan... we are going to the moon to prepare for Mars and beyond, so that would make sense.

Michael Bloxham · 2004-01-23 18:57:39

Umm, what is [http://boeingmedia.com/images/one.cfm?i … &release=t]this? Boeing needs to fire them crack smoking hippies... Save us, ZubrinMan!

clark · 2004-01-23 20:18:12

what should it look like?

Josh Cryer · 2004-01-23 21:30:14

Those designs are good.

Ad Astra · 2004-01-25 02:11:19

I see ups and downs to what Boeing's put on the table. On the plus side, they make maximum use of existing hardware (Delta IV upper stages for lunar injection, etc) and the design is quite modular. However, I had to scream "Battlestar Galactica!" when I saw their monster Mars spaceship. It's supposed to be built in lunar orbit. Assuming the components will be built on earth, why build the ship at the moon?

Ultimately we will need nuclear thermal and nuclear electric rockets before 2020. Boeing makes no mention of this (but the other site mentioned at the beginning of this thread did.)

Unfortunately, the consolidation of the defense industry has stifled creativity in designing the missions and components. Firms with space experience have folded--Lockheed swallowed Martin and the air / space division of General Dynamics, while Boeing ate McDonnell Douglas and North American Rockwell. That's why we need guys like Zubrin and Burt Rutan to agitate the system and force these corpulent conglomerates to think outside the box.

Rxke · 2004-01-25 13:57:10

Ad Astra, yes, it's strange they want to build it around the moon...
Payload-wise it makes no sense, while building it...
Or is it, ultimately, to be able to use a leaner ship to Mars (less propellant needed from around the moon)? Should be, but is it worth the payload penalty *building* the ship? Not to mention the higher complexity....

Anyway, looks ISS is totally out of the picture in this scenario(!)

Rxke · 2004-01-25 14:03:59

Like the modularity, huge money saver if they get it right. You only have to develop one system that can be used in different combinations, sometimes that will mean a weight-penalty, but so be it, simplicity *works*
Also that way you get your hardware tested a lot faster: imagine an unmanned cargo lander using identical landing gear as the manned version, while you test one design, by actually landing it, you test, in fact another too: the manned version...

And so on. One thing about their Mars errr... thing... They forgot the big antenna in the middle, nevermind 2001 has passed 3 years ago! :;):

Ad Astra · 2004-01-25 14:49:26

It looks like Boeing's "Battlestar Galactica" uses some kind of nuclear propulsion, probably NTR but possibly VASIMR. The engines are connected to a truss and located far away from the crew portions, and the propellant tanks insulate the crew from the radiation.

RobS · 2004-01-25 16:37:33

I think the Mars version of the Boeing Proposal uses 12 Delta-IV Large launches to put the equivalent of the second stage into orbit, but without engines. These are then attached to a truss, at the end of which are two large chemical engines. The twelve tanks are probably dropped one by one as they are emptied.

While somewhere else a lunar orbit station is mentioned as a place to assemble a Mars ship, I doubt this ship is assembled there. This is a ship for low earth orbit, unless the twelve tanks were sent to the moon with fuel to propell something else there, got emptied and stored, and then were filled up with new lunar fuel.

Physics dictate that if you want to fly from Earth to Mars, you fire your engines as close to Earth as possible. That's because of the relationship between delta-v, escape velocity, and hyperbolic velocity is like a pythagorean triangle:

reentry velocity squared = escape velocity squared plus hyperbolic velocity squared

reentry velocity is the velocity a spacecraft is moving when it crashes into the surface; it's also the velocity of an outgoing spacecraft when the engines shut down

escape velocity is the velocity something needs to escape from a planet

hyperbolic velocity is the speed something is left with after escaping from a planet.

Thus if a planet's escape velocity is 3 km/sec and a ship leaves the planet at 5 km/sec, it ends up with 4 km/sec after it has left because 5 squared (25) = 3 squared (9) + 4 squared (16).

Here's a thought experiment for you: start with an "apple" 1,000 miles above the Earth and drop it. It'll accelerate and hit the surface after so many minutes at a certain speed. But take an apple at 1,000 miles altitude and fire it at the earth at 10,000 miles per hour. If there were no gravitational acceleration, it'd hit the earth in 6 minutes. Six minutes won't give the earth's gravity much time to acccelerate it, so gravite won't speed it up as much as in case 1 when it started out with zero velocity. Now, apply this in reverse: the faster you leave a gravitational field, the less time it has to slow you down, so you leave with more of the initial impulse.

SO, if you want to go to Mars, you fire your engines just above the earth's atmosphere, deep in its gravitational field.

That doesn't mean the moon is irrelevant, though. You can fuel up in a very, very high lunar orbit with lunar fuel if it's available. The bext spot is the lagrange point because you don't have to fire your engines at all to leave the moon's gravity. When you want to go to Mars, you fire your engines and go to Earth first, where you perform trans-Mars injection at closest approach. To get to Earth, there are two trajectories:

Delta-v, 0.5 km/sec: This cancels out the lagrange point's orbital speed around the earth, causing you to fall toward the Earth.

Delta-v, 0.2 km/sec; This causes you to fall to the moon instead, where you fly around the moon, using its gravity to send you back toward the lagrange point, but this time without the circular motion, so you continue on to Earth.

Overall, the main disappointment I have with the Boeing "plan" is that it requires an incredible number of launches. Their Mars vehicle uses 12 tanks derived from their Delta-IV second stage, which masses 30.7 tonnes (3.5 tonnes stage, 27.2 tonnes fuel). That's 360 tonnes of stuff to push everything else to Mars, which must mass about 100 tonnes. That's a LOT of launches at $170 million each! It's Mars Direct without the direct. It would be better to develop a solar-ion tug to move everything to high orbit or Lagrange, then haul up a small amount of fuel to do the rest, or use lunar fuel. Fortunately, the new Mars Society statement says a large aerospace company (I suppose Boeing) says they can develop a much larger booster from their EELV family, reducing the total launches.

I plan to print out the pictures--if I can--and study them in more detail. But it's really too soon to know whether this plan is serious or not. We're too early in the planning cycle.

-- RobS

Ad Astra · 2004-01-25 17:54:47

Maximizing the number of launches is definitely in Boeing's best interests, as it means more Boeing-built Delta-IV heavies will be produced. If Boeing were given a contract for the hardware while Lockheed Martin or RSC-Energia or Arianespace got the contract for the booster, I think Boeing would be more disciplined in their packaging and assembly strategies.

Shaun Barrett · 2004-01-25 20:25:27

That was a very informative post, Rob. Thanks!

I didn't quite follow the logic of launching from as deep in Earth's gravity well as possible to get to Mars. Ideally, I'd need to see diagrams, equations and examples of calculations.
I believe I have the first stirrings of an understanding of what you're driving at, even though it appears counter-intuitive on the surface. But it hasn't quite sunk in!
I guess I'm a little slow at times.

dicktice · 2004-01-26 09:34:55

Shaun: You're not slow, just cautious, because this is real--not just futuristic pipedreaming. Please keep it up, because at my advanced age these approaches give me hope that I'll actually live to see it happen!

Rxke · 2004-01-26 10:26:00

for the SF fans, this (RobS) explanation is used by Arthur C Clarke in his (pen?)ultimate Space Odyssey, but with jupiter, IIRC. They use jupiters gravity to do the initial escape-burn, before it becomes another star...

RobS, do you see *any* advantage about the moon orbit cq Mars launches instead of a LEO? In their proposal they *do* state they want to build it in Moon orbit, something that i cannot understand... i thought i was missing something, that it was indeed simpler to launch from Moon orbit, but it isn't, after all. it should be Lagrange, as there *was* talk about a Lagrange station or something.

And indeed: TWELVE launches? uh-oh...

clark · 2004-01-26 10:46:56

Does any of this matter with nuclear propulsion?

Assume that we will not be using chemical rockets for any Mars mission. Assume that a 'space-tug' utilizing ion-propulsion will be used to move Delta-heavy launch sized mass from LEO to the L1 liberation point.

Does it then make sense to, or is there a problem in building near the Moon?

Given Boeing's proposal, and just thinking of possibilities, might we see the various cast off modules from previous moon missions being assembled into new configurations as the moon missions progress?

So the trans-lunar insertion stage takes the first manned mission to the Moon- it stays in lunar orbit, the command module brings the men home. 2nd manned mission brings another trans-lunar insertion, with some additional modules, which are then attached to the previos modules in orbit of Luna. Thus slowly building a L1 "space station" from discarded lunar missions.

Just a thought.

Rxke · 2004-01-26 12:03:25

Good thought, several different space-tugs are in the workings, so....

Somewhere else i already screamed: "a tug, a tug, my kingdom for a tug!"

BTW, might be of interest: [http://www.aviationnow.com/avnow/news/c … 264wna.xml]Aviation Now article about the effects Bush new plan has ona NASA et al.

RobW · 2004-01-26 12:58:30

L1 gives you the best of both worlds (Moon & Earth) - literally. It provides a place where you can assemble (ie dock together the modules of) your Mars ship, close enough to the Moon to make lunar propellant worthwhile. Modules launched from Earth (except the one with the crew, of course) can take the 'slow boat' in the form of solar-ion propulsion to get a reasonable sized payload to L1 from a delta-IV launch. Then, when you're all fueled up and ready to go, you only need a brief nudge to set you sliding down the gravity well toward Earth, where you fire your TMI stage both close to Earth and already travelling faster than an LEO orbit, increasing the effective velocity change you can get from that fuel.

Personally, I think that Boeing is using terms like 'in orbit around the Moon' because it thinks L1 is too hard to explain to the general public. Theres not a lot of merit in assembling a Mars ship in a genuine Lunar orbit.

New Mars Forums

Announcement

#26 2004-01-22 09:01:38

Re: Post central for information on CEV - iformation station for the spacecraft

#27 2004-01-22 09:15:56

Re: Post central for information on CEV - iformation station for the spacecraft

#28 2004-01-22 11:01:56

Re: Post central for information on CEV - iformation station for the spacecraft

#29 2004-01-22 11:16:04

Re: Post central for information on CEV - iformation station for the spacecraft

#30 2004-01-22 11:25:06

Re: Post central for information on CEV - iformation station for the spacecraft

#31 2004-01-22 11:27:30

Re: Post central for information on CEV - iformation station for the spacecraft

#32 2004-01-23 12:22:23

Re: Post central for information on CEV - iformation station for the spacecraft

#33 2004-01-23 12:38:21

Re: Post central for information on CEV - iformation station for the spacecraft

#34 2004-01-23 12:55:54

Re: Post central for information on CEV - iformation station for the spacecraft

#35 2004-01-23 17:19:13

Re: Post central for information on CEV - iformation station for the spacecraft

#36 2004-01-23 18:57:39

Re: Post central for information on CEV - iformation station for the spacecraft

#37 2004-01-23 20:18:12

Re: Post central for information on CEV - iformation station for the spacecraft

#38 2004-01-23 21:30:14

Re: Post central for information on CEV - iformation station for the spacecraft

#39 2004-01-25 02:11:19

Re: Post central for information on CEV - iformation station for the spacecraft

#40 2004-01-25 13:57:10

Re: Post central for information on CEV - iformation station for the spacecraft

#41 2004-01-25 14:03:59

Re: Post central for information on CEV - iformation station for the spacecraft

#42 2004-01-25 14:49:26

Re: Post central for information on CEV - iformation station for the spacecraft

#43 2004-01-25 16:37:33

Re: Post central for information on CEV - iformation station for the spacecraft

#44 2004-01-25 17:54:47

Re: Post central for information on CEV - iformation station for the spacecraft

#45 2004-01-25 20:25:27

Re: Post central for information on CEV - iformation station for the spacecraft

#46 2004-01-26 09:34:55

Re: Post central for information on CEV - iformation station for the spacecraft

#47 2004-01-26 10:26:00

Re: Post central for information on CEV - iformation station for the spacecraft

#48 2004-01-26 10:46:56

Re: Post central for information on CEV - iformation station for the spacecraft

#49 2004-01-26 12:03:25

Re: Post central for information on CEV - iformation station for the spacecraft

#50 2004-01-26 12:58:30

Re: Post central for information on CEV - iformation station for the spacecraft

Board footer