That ugly bastard’s back.

Wonder what the crew of Discovery have been doing since they undocked from the International Space Station and will be doing until they land in a little under 24 hours? Well, a big part of that work is to adjust their sleep schedules. [Heh.] Station sleep/wake cycles don’t match up with when Discovery is to land, so they spend some time getting enough sleep so that, once the time comes to land, that’s about “mid-morning” or so for them.

Am I happy with how STS-114 has gone? Generally, yeah. It’s been a great mission. But I won’t feel good I see two puffs of smoke come out from under the tires on the Orbiter’s landing gear and then see that big ol’ nose come down on the third axle.

Godspeed, Discovery, and we’ll see you soon.

The San Francisco Chronicle has an article in the Sunday paper about the NASA’s next generation launch vehicles. It’s like what you’ve read here before, but they address single-stage-to-orbit when talking about the “space plane” concept.

Let me tell you why SSTO fails miserably. With multi-stage rockets, especially liquid-fueled rockets, your structure is also your tanking. You make very thin-walled rockets, stuff barely able to stand up on its own without being under pressure. In fact, if you launched these things unpressurized, these things would just rip completely apart. Why do you do this? Structure is “dumb mass”—it just doesn’t do anything.

When you have a multi-stage rocket, you shed dumb mass as you go through stages. When you’re done with a stage, you jettison it, and the next stage doesn’t have to carry that mass on through the next phase.

When you do SSTO, you’re stuck with the structure for the entire flight. You need structure, of course—millions of pounds of thrust has to be resisted. Newton’s Third Law doesn’t just apply to the overall system, but also to internal components. [In fact, N3L is the basis of finite element analysis of structures.] If you’re carrying structure for the whole flight, that’s less usable mass.

We ran the numbers once in undergrad propulsion … the best an SSTO vehicle can do is to expect to carry 3% mass fraction of usable mass. But that’s everything … crew, the food, water, and air they breathe … everything.

Now, that doesn’t seem bad, does it? Well, when you run the numbers for what that 3% needs to be to do a good mission, that vehicle ends up being prohibitively expensive.

And mind you, 3% is a very liberal figure. The real answer is probably lower.

SSTO was a great concept, but it was a pipe dream. Sticking with multi-stage and going back to capsules and modules is the way to go, and that’s where NASA is headed.

I remember laughing when I read John’s post yesterday:

And, before I get flamed out of existence by my friends in the aerospace industry, let me point out that I think the space program was great, like, when I was in grade school. But come on Shuttle fans, give it up… we need a new vision of space exploration.

Gee, John, were you thinking of me just then?

There’s no doubt that I’m a fan of Shuttle, in many ways. I mean, heck … when you work on cargo transfer to the International Space Station, as I do, and the only heavy cargo lift vehicle you have at your disposal is the Shuttle system, well … you’re pre-disposed to liking it.

But let me say that Maciej Ceglowski’s review of the sad history of STS is spot on in almost every regard. Appropriately titled “A Rocket to Nowhere”, Ceglowski gives his readers an excellent run-down of all the things that are wrong with STS, including one I always forget to mention when I talk about STS’s flaws: the polar orbit design constraint.

The Air Force was only too happy to agree, but at a crippling price. What the Air Force wanted to launch was spy satellites – lots of them, bulky telescopes with heavy mirrors, the bigger the better – and it wanted to launch them in an orbit over the Earth’s poles, so they could snoop over the maximum amount of Red territory. This meant NASA had to go back to the drawing board, since polar orbits would require a heavier orbiter than the Shuttle design had anticipated 2 , which in turn meant using a bigger rocket at launch, and dissipating more heat during re-entry.

Moreover, there was no way to launch a polar mission safely from Kennedy Space Center – it would mean overflying either heavily populated areas in the Carolinas or risking capture of a fuel tank by the wily Cubans. So the Air Force also demanded, and got, billions in funding to build a new Shuttle launch facility at Vandenberg Air Force base in California. And because some of the Air Force’s military missions involved capturing a Soviet satellite on the sly and landing after one orbit, the Air Force demanded that the Shuttle be capable of gliding over a thousand miles cross-range during re-entry, so that it could catch up with the rapidly eastbound Air Force base underneath it. This meant bigger wings, which in turn meant more weight, an even more powerful rocket, and again a more complicated heat shield.

After it became clear that the Space Shuttle was going to also be the Space Tug, it was clear that there were going to be massive compromises in the system. Any aerospace designer will tell you that the efficiency of any vehicle at doing any mission is inversely proportional to the number of missions it must perform. Simply put, Shuttle was asked to do too much.

[On that four-piece system: the original idea was a Space Station, serviced by a Space Shuttle and a Space Tug that would bring up crew and cargo, respectively. There would also be a Space Telescope, which did end up being developed as the Hubble Space Telescope.]

One thing that Ceglowski doesn’t note—probably because he didn’t know it—was that Columbia had been pulled off of ISS duty. Why? Orbiter airframes are rated for only so many flights—past that, they’re to be retired. A flight up to ISS puts the airframe under more stress than does a free flight out over the Atlantic, purely because the STS can’t make full use of the Earth’s rotation. ISS is at a much higher orbital inclination because Baikonour Cosmodrome was used as the launch constraint. An ISS launch hugs the East Coast before taking a right at Nova Scotia, rather than going out over Africa.

My only quibble with Ceglowski? He takes a swipe at the use of solid rockets for STS. I think that he’s wrong there: solids are better for the application they’re used for. Did design constraints push us to augment the SSME’s with the SRB’s? Yes, and that’s unfortunate. But, given the design constraints in place, the SRB’s are great for what we need them to do: provide peak thrust power in the early part of the flight transition.

And yes, I say that with a straight face, thinking back to Challenger. That was just a huge mistake on a we-must-launch-now mode.

Now, where do all these constraints come in? Politics. The Air Force played politics with Congress and NASA on constraining the Shuttle. [Of course, NASA needed the work at the time, since the Space Station was far off ... we thought we'd have it in the late 1980s, and we finally got it a decade later, when Shuttle was almost old enough to buy cigarettes in most states.] Flight decisions were made for political and not technical reasons. [The old story about a push to fly Challenger on 26-Jan to support a State of the Union Address by Reagan is disputed, but it generally rings true.]

I want to thank Maciej for being an even-handed critic of Shuttle. I am ready for Shuttle to go away … I’m far readier for a Vision for Space Exploration that breathes new life into NASA. But I also get to have fun in helping build carriers for other cargo rockets. And all that fun starts later this month for me.

Mike asks [on the Rumor Forum in a private forum]: “Why does the astronaut in this photo have a mirrored glare on his visor?

The answer’s pretty simple: there’s a thin layer of gold foil on those visors, encased in plastic, to deal with cosmic radiation.

Keith Cowing is right: if not for the PAL foam issue, everyone would be praising NASA for how well this mission has gone. But because of the foam issue right on the first day, the whole mission had a pall cast over it, and even Steve Robinson’s great ride over the Orbiter’s underbelly plucking out gap fillers was seen as a risky, Dutch-boy-plugging-the-dike endeavor instead of what it was—NASA flexing its technical muscle and showing why the crew is so thoroughly trained before we go up.

What will be most interesting to me is final data on the number of nicks in the thermal protection system’s tiles. We know that, on average, 150 tiles are damaged each mission. All the imagery we have to date on the tiles shows that only 25 were damaged on launch. I think that we’ve always assumed that launch is where we pick up all the damage, but I have this nagging sensation that it’s equal parts launch and landing. If nothing else, Return to Flight has us acquiring tons more data on Shuttle … it’s just too damn bad that we’re doing it now, 25 years after its inception.

Let this be a lesson to all of us in the NASA world: we need all the data we can reasonably get about spacecraft performance, and we need to have baselines on our performance. And, when, capabilities expand our ability to get in-flight data, we must sieze on that.

And for any wondering … yes, I’ll address Maciej Ceglowski’s scathing review of the Shuttle’s history later in the Blogathon. And no, it’s probably not what you’d expect me to say about it.

Discovery above Earth

Originally uploaded by gfmorris.

And for all of you who wonder what the heck it is that I do at work, well … you can see some of it here.

We built the FRAMs that are mounted to the Lightweight MPESS Carrier [LMC] in the middle of the Orbite’s Payload Bay. The big cylinder at the back is the Rafaello Mulit-Purpose Logistics Module [MPLM], which carries cargo up and down to ISS in the Payload Bay. I work on Cargo Mission Contract, and we manage the cargo carried in the MPLMs.

I know I touched the FSE that’s riding on one of those FRAMs with my own bare hands … it carried up one of the Control Moment Gyroscopes that keep the ISS oriented properly. As I find photos of our work stuff online, I’ll add it to my work products photoset on Flickr.

I have two words in response to Gene Kranz’s op-ed in the NYT: Hell yeah.

Second one took even less force.

Total of ten minutes for Steve Robinson to remove both gap fillers. Almost all of that time was Robinson and Sergei Krikalev working out how to move Robinson carefully around the back side of the orbiter. The whole motion is like reaching around to scratch between your shoulder blades, and in space, you don’t do anything quickly.

Dear New York Times: Bite our shiny metal asses. You doubt crew? Wankers. All a bunch of wankers.

Steve Robinson just pulled the first gap filler out! Only took him 1.5 lbf to remove it. I’ve got TiVo running downstairs on a 10.5 hr recording of this entire EVA [#3 on STS-114]. Two quotes from Robinson: “To an old aerodynamicist like me, looking at this thing up close up here is just like viewing a work of art.” “There’s just nothing to see here, guys,” referring to any damage in the area of the first piece of gap filler.

NASA TV rules when we have people doing stuff.

Jason Levine has it dead right: more data isn’t always a good thing. He’s right: everyone’s having to scramble for answers with data we’ve never had before, and everyone’s getting to do it under time pressure—Discovery has to come home at some point, or we have to roll out Atlantis and do the kamikaze STS-300 rescue mission—and with a huge amount of skepticism from the media. [I mean, the NYT editorial pages are absolutely killing NASA right now.]

It’s an unenviable position. I have a friend who works down at Michoud Assembly Facility, where they build the External Tanks. Hearing his stories via our backchannels is simultaneously amusing and disheartening.

It’s still all experimental, folks. It’s frankly awesome that we have all this great amount of data. In our meetings at work—folks that have nothing to do with the Space Shuttle Program, other than our work products ride up in it—we’ve been asking, “Why haven’t we had this data before?” It’s a great question, sure, but it’s a non-starter—we haven’t had it, but we do now, and we have to weigh all this torrent of new data against experience in flying 100+ missions previous to this.

I’m still quite confident that, on the whole, the right decisions are being made. I’ll be happy when I see media people stop playing armchair engineer, but I don’t expect that it’ll happen.

[Heck, I'm posting this in large part because he's disabled comments, and posting a link and trackbacking is faster for me than digging up his email address somewhere. Good on you, Jason.]

Most days, NASA TV is about as enjoyable as a test pattern. [I've used it as an insomnia cure before.] I’ve always said, though, that it’s interesting to watch during a mission. With everything going on with Discovery and the gap filler flap, it’s doubly interesting. I’m home with a migraine today [thankfully, it's fading, and I can stand to have my eyes open], and I just finished watching some B-roll tape of folks from the EVA [and probably VITT] office running through the procedures of pulling, sawing, and slicing the gap filler. Not only did you see a gaggle of reporters get to stand [and I think, later in the roll, actually attempt] and watch the EVA folks do the ops with gloves on, but then you see a Neutral Buoyancy Tank run done by one of the crew guys running the same ops.

I don’t think Ron Howard will make a movie of this, but … it’s pretty dadgum interesting stuff. I’m lucky to live in Huntsville, where NASA TV is a part of basic cable. And right now … a lovely view of the Pacific Northwest as the ISS traverses the area around the U.S.-Canada border.

It’s also cool to note that the Control Moment Gyroscopes are just now verified to be back online, with the Shuttle Orbiter just now, right before noon CDT, turning ISS attitude control back to the CMG’s. Why is this making me happy? We built the CMG’s cradle carrier, which held the spare that was just installed and that will bring home the faulty unit when Discovery comes home.

Update: Watching ABC’s evening news tonight, a lot of that B-roll footage ended up in part of their news story behind a voice-over. Good stuff.

NASA’s initial plans for manned missions to the Moon and Mars have been leaked to the Orlando Sentinel. Doing this with two rockets is an interesting approach, but … I like it.

Michael Heileman seems to think that it must be frustrating to work in the space program and send someone else to orbit. As an employee of a NASA contractor, I wholeheartedly disagree … and if you’d been sitting in the room where I was, watching the launch on a really grainy TV [over-the-air signal + TV as old as I am + metal building = not being able to read the countdown clock ], you’d have understood. We held a lot of breath this morning.

There was no big celebration, either. No high fives, no happy dances. Just a feeling of satisfaction, and then a desire to get back to work.

It’s a damn shame, though, that we in the contractor community don’t stop, take a breath, and watch every launch and landing as a team. We really should. I have my corrective action for our next status meeting.

Me: “No. They haven’t cut the engines off yet.”

Misty: “Oh, I thought you would’ve been doing a dance yet.”

“I don’t dance until they’re really and truly up there.”

But they’re really and truly up there.

God speed, Discovery. Tell Sergei and John howdy.

We’re back.