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http://www.spacedaily.com/news/rocketsc … tml]Falcon I structural testing

Now the inaugural launch is scheduled for late summer.

The smaller the RLV payload, the more economic sense it makes.  That's why the RLV startups got so excited about Iridium, because it would put up a constellation of many small satellites.  The launch frequency determines whether a launch vehicle should be expendable, partially-reusable, or fully reusable.

The original DC-X business model was a work of genius.  SDIO needed to put thousands of tiny "Brilliant Pebbles" interceptors in space, so they wanted McDonnell Douglas to build them a vehicle that would launch an interceptor, return to earth, and be ready to fly again within days instead of months.

If our industry is bold enough, they will catch on.  They will build a 25 MT RLV, make it able to turn around in two weeks or less, and make the moon cheap and accessable.

http://www.spacedaily.com/news/rocketsc … .html]Pres. Bush cancels Shuttle

I almost got excited until I got to the second paragraph and realized it was a joke.  SpaceDaily almost got my hopes up.

Does anybody out here agree with me that serious news services should refrain from these kinds of April Fools' jokes?

One obstacle to making an HLLV with one engine per stage is the difficulty of making a single engine that's big enough to lift the weight of the rocket.  Imagine building an engine that can putout six million pounds of thrust for an HLLV.

There seems to be an optimal number of engines for any given vehicle.  Most aircraft are designed to survive a single engine failure; that's why almost all passenger planes (with the exception of the massive A380, which falls under the same category as my first paragraph) have only two engines.  That's also why the single-engine F-16 is nicknamed "the lawn dart."

The exorbitant number of engines on the N1 obviously argues against engine-out.  I tend to think that 5 engines per stage is an optimal number.  If each engine has a statistical failure risk of 2% or so, we have to weigh the benefits of single engine-out capabilities versus the added risk of failure.

At this point, even Homer Hickam (of "Rocket Boys" / "October Sky" fame) is advocating a quick end to the shuttle program and a new emphasis on going back to the moon.  Presumably this means he opposes a Hubble servicing mission too.

The irony is that in the immediate aftermath of Columbia's loss, Hickam believed the shuttle should be flown until ISS was completed, then replaced with OSP.

Michael Griffin will undoubtedly feel a lot of pressure from various sectors to restore Hubble SM4.  He's new to the job and Hubble's supporters think they can mold him like a lump of clay.  At the same time, the White House budget office can overrule an SM4 restoration by denying NASA the funds for the mission.  It will be interesting to see how this plays out, but unless Griffin restores a robotic servicing mission, Hubble is toast.

(Personally, I'd like to see a robot fix Hubble's gyros and batteries, if only to push the state-of-the-art in robotics.  Any new Hubble instruments should have to wait for the Hubble Origins Probe.)

I was referring to the launch tower, not the escape tower on the top of the capsule.  The launh tower will need to be redone for astronauts, so they can ride the elevator up to their capsule, get strapped inside, and quickly zip-line away if the mission is aborted on the pad.

When looking at SDV and EELV cost, it's important to note the following:

Right now, NASA is paying over $3 bil per year for the shuttle program.  NASA has only paid for a few EELV launches because they fly so infrequently, and usually with commercial or military payloads.

NASA has three options for VSE: all-SDV, SDV + EELV, and all-EELV.  The first scenario would force NASA to add to its operations cost for CEV capsule operations.  SDV + EELV forces NASA to add this CEV operations cost AND increase its EELV buys substantially.  The third scenario adds CEV costs and makes NASA buy more EELV's, but shuttle costs vanish.

Under this logic, all-SDV makes the most sense in my mind.  But there's a catch: Most engineers (myself included) would not trust the manned CEV on a traditional SDV design.  You would want to instead build an in-line SDV with the CEV on top.  This becomes prohibitively expensive as commonality with the old ET is lost.

If all-SDV is off the table, we are left with the choice of SDV + EELV or EELV-only.  We've acknowledged the difficulties of EELV-only already.  For SDV + EELV to work, however, NASA MUST find a way to cut the shuttle fixed launch costs so it can afford the extra EELV launch that is required for each manned CEV.

Another thing worth considering is the pad and tower modifications needed to put a manned CEV on an EELV.  They will need crew access gantries, elevators, escape baskets, and the other niceties that go into crew egress.

I just listened to a presentation from a Scaled Compostes employee; he says that while Burt Rutan is dreaming about orbital spaceflight, he has no solution to the problem, and he is not in the running for the Bigelow prize.

I briefly read Zubrin's trio and I've found many problems.  His analysis is very simplistic and he prematurely rules out the possibility that "QQ" would reliably work.

It would be silly to assume you could launch four heavy EELV's in a month.  The way to get around this is an Apollo-like solution: put storable propellants in the lander.  Apollo used N2O4 and MMH; I prefer H2O2 and kerosene because it's less nasty to work with.  You could keep the LSAM in lunar orbit (which according to Zubrin is unstable) for another month while waiting for the CEV to come.

QQ will avoid an Apollo 13 style accident.  I've heard that NASA is going solar instead of fuel cells for the spaceship's power system for this very reason.  Further, you can avoid docking the LSAM "lifeboat" with the CEV for the same reason that Mars Direct doesn't have a separate mothership and lander: just build redundant systems into the ship.  The lifeboat was a redundant system.  You don't need a lifeboat to duplicate all of the CEV's functions as long as you have redundant systems that are spaced far enough apart, so a common problem doesn't disable the backups.

Even if one in four missions fails, it doesn't mean loss of crew.  There are more failure scenarios where the crew is saved than scenarios where the crew is killed.  The mission could be scrubbed before EDS 1 pushes the LSAM to the moon.  The LSAM or either EDS could blow up on the pad.  Even if the CEV booster blew up, an escape system could save the crew.

I found it interesting that Zubrin's CEV would be so light (12 MT) and his LSAM so heavy.  The Grumman engineers of the 60's did a marvelous job making the LEM as flimsy as possible to save weight in the near-weightless environment.  This time around, NASA is looking at designs that are even more austere, like open cockpits.

There isn't enough space here to totally deconstruct Zubrin, but the point is that we can do the moon without an HLLV or direct landing.  Perhaps the plan should be to get to the moon initially by QQ in the 2015-2020 time frame, then develop a new HLLV in time for Mars by 2030.

I'm in total agreement with BWhite.  We may be able to avoid an HLLV for the lunar return but it's a must for Mars.  Because we're delaying Mars beyond 2030, maybe we'll find the money to develop and build a clean-sheet HLLV.

The other obstacle I forsee in getting to Mars is what Robert Zubrin calls "the lunar siren."  Unlike Zubrin, I believe there is much to be gained from going to the moon.  But Mars is also a priority once the technology is mature enough for humans to go safely. 

The key will be a smooth transition from our lunar exporation program to Mars exploration.  The easiest way to do this, in my view, is to involve private enterprise in the lunar retrn from the start.  The moon base operation will be gradually privatized as NASA gears up for Mars.  If this doesn't happen, we will have to either abandon the moon, or stick with the moon and forget about Mars.

I have been hearing many complaints (especially on NASAwatch.com) about the de-funding of aeronautics research at NASA.  Granted,most of the negative comments come from NASA's aeronautics-related employees who stand to lose big from the downsizing.  I happen to have mixed feelings about it.

On one hand, it's sad to see historic facilities like Ames and Langley being put on the chopping block, with the possibility that they could totally disappear in the near future.  There is plenty of room for aeronautics research and America's leadership in this field is being challenged.  NASA needs to take the lead.

At the same time, the US has a robust aviation industry that is capable of conducting its own research.  Must taxpayer dollars be used for research that will directly benefit the "three stooges" of the aerospace industry?

I believe the solution is for NASA to reduce its aeronautics workforce but pursue more cooperative research with the industry that relies on private funding.  There is a need for a National Advisory Committee for Aeronautics again, to symbolically emphasize our commitment to aeronautics even as we pursue the Vision for Space Exploration.  NACA and the industry should cooperate on the aeronautical advances that will bring about scramjets and more efficient airliners.

I got a native Russian speaker to translate the Kliper schematics.