Category Archives: Space

General Science, Science And Society, Space

Free Fall

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As Clark notes, here is a very nicely written piece on parabolic flight and weightlessness. Rare is the reporter (even science reporters) who get the physics right on this, because (as he points out) they get confused by the phrase “zero gravity,” which doesn’t really exist anywhere in the universe. Only one quibble:

Each period of ‘weightlessness’ is limited to half a minute or so; otherwise we ‘zeronauts’ would continue freefalling right into the Nevada desert at 600mph. As it is, during half-a-minute’s power- dive we drop nearly 20,000ft – although inside the plane we are completely unaware of this.

This gives the impression that weightlessness only occurs when you “drop” (i.e., descend in altitude). But it actually happens on the way up as well. In both cases, you are “falling” (in the sense that there is no force acting on you other than gravity). First you fall up, then hit the top of the trajectory, then fall down, weightless all the while, and unable to discern your direction of motion. If this seems counterintuitive, it is. But consider an elliptical orbit. As you approach perigee you’re heading down (toward the earth), and once you reach it, you start heading back up (away from the earth) to apogee, but you’re in orbit, and free fall the entire orbit. A parabola in an aircraft is an orbit that, if continued, would intersect the earth’s surface (which is why it is wise to not continue it). And of course, to be more technical yet, it is only parabolic in an approximate sense (assuming flat earth). In reality, it is a tiny section of an ellipse, because the contents of the aircraft are (briefly) in orbit, within the atmosphere.

I should also note that the phrase “power dive” is also misleading. “Power dive” implies that you are diving with engines at full thrust to get down as fast as possible, but in fact, the engines are barely running above idle throughout (until the pullout). Their only function is to overcome wind resistance so that the aircraft can approximate a cannon ball falling in vacuum.

Political Commentary, Space

Shuttle, Ares and EELVs

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There are some interesting top stories over at Space News this weekend. First, there is discussion of the results of the Shuttle extension study, which says that it would be possible to extend Shuttle all the way to 2015 without impacting Ares development, as long as additional budget was provided. One of the biggest arguments against it is the risk of losing another orbiter:

According to the study, both options increase the risk of losing a crew or vehicle: The two-year extension increases the cumulative risk from a 1-in-8 probability to 1 in 6; extending operations through 2015 increases the risk to 1 in 4. The risk of losing an orbiter or crew on any given mission is 1 in 77, the report said.

I know that in the past NASA has been too optimistic about probability of crew/vehicle loss, but I think that 1 in 77 is probably too conservative now. I suspect that, post Columbia (and resolution of the foam issue and ability to inspect and safe haven at ISS for all missions other than Hubble), the Shuttle is probably as safe, or safer to fly now than it’s ever been. That’s not necessarily an argument not to retire it, but I don’t think that the risk of vehicle or crew loss is a compelling argument against extension, either.

I would seriously dispute this comment from Mike Griffin:

In a Dec. 15 interview, Griffin called reliance on Soyuz “unfortunate in the extreme,” but said NASA needs the $3 billion it spends annually on shuttle to move ahead with the replacement system.

“Every time I have spoken about [the gap] I’ve laid it at the feet of budget,” Griffin said. He emphasized that without an increase in NASA’s overall budget, extending shuttle operations will result in a corresponding delay to Orion-Ares 1.

I’ve got a better set of feet to lay it at — Mike Griffin’s decision to develop an unneeded new launch vehicle, which was not intended within the vision or the budget “sand pile.” He knew what the budget was going to be, but rather than moving out on developing actual exploration hardware, and encouraging private industry to get people to LEO via COTS D or something similar, he decided to take that money and develop Ares.

Speaking of which, he appears to be losing the battle to save it:

Griffin said NASA also explored the possibility of developing a larger rocket based on EELV hardware and systems. “We went through it and we came up with the answer that the EELV-derived solution didn’t save you any schedule, didn’t save you any money, wasn’t that safe, and when you look at going beyond the space station mission to the heavy-lift architecture, was quite a bit more expensive. So it didn’t win on any count,” Griffin said. “At this point I’m kind of wondering what has to happen to have people say, ‘OK, I guess they got it right.'”

No need to wonder, Mike. Here’s what has to happen. Show us the actual results of the analysis, along with the assumptions. Then we’ll be able to decide whether or not “they got it right.” Until you do so, we will remain (appropriately) skeptical. It’s too big a decision, with too many implications for taxpayers’ dollars, and our future in space, to just take your (and Scott Horowitz’ and Doug Stanley’s) word for it.

Finally, there is a story that claims that the Orbital proposal for COTS, which was the highest cost, was also the lowest rated. Given Dr. Griffin’s history (and potentially future) with OSC, this will be sure to raise some eyebrows. Particularly since it looks like Planet Space is going to protest. Charles Lurio notes via email that he has a source who claims that:

…a reason for rejecting Planetspace was that Griffin didn’t want an EELV to be used, since, though the only flights would be unmanned, it would further underscore to people that EELV was a viable alternative to Ares 1.

At the time, it sounded like an extreme story even given Griffin’s mania to save Ares 1.

Now, with the comment in the Space News item that Orbital had, “the highest price and lowest score,” I’m starting to think that the story may be a lot more plausible.

Unfortunately, it may be. He’s really on the defensive.

Clark Lindsey has more.

Political Commentary, Science And Society, Space, Technology and Society

Death From The Heavens

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Was there a major meteoritic strike 13,000 years ago in North America?

That wasn’t very long ago (compared to, say, the sixty-five million years ago that the Yucatan was hit). Evidence continues to accumulate that we get hit a lot more than people have previously imagined. We really need to develop the capability to do something about it. We have technology in hand to do so, but apparently lack the will to deploy it. This by itself is reason enough to make the investment to become a real spacefaring civilization, but pork and maintaining existing jobs remain more important.

Administrative, Political Commentary, Space

Have It Your Way

6 Comments

This has actually been true since I switched to Word Press, but it’s now possible to view specific category posts. For instance, by clicking on the space category, you can see only space stuff (for those who have complained over the years that they like my space posts, but aren’t interested in, or are put off by, my political posts). Likewise, those who like the politics without the space can use this page instead. Or any of the other categories, though those two are probably updated most often. Same thing applies to people who have me on their blogroll as a service to their readers, but don’t necessarily want to subject them to what they might consider off-topic blather (e.g., Alan Boyle or Clark Lindsey, or Jon Goff might only want to blogroll the space category).

Political Commentary, Space, Space and Campaign 2008

Continuing To Take Sides

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I admire Neil Armstrong greatly. He’s a great man, and a great engineer. I was privileged to see him a few years ago at a rare public appearance — a commencement address, which was appropriately humble, and focused on not himself but on the graduates, as a good commencement address should be.

That said, I don’t necessarily take anything he says about modern space policy seriously. This is because a) he and I don’t necessarily share the same goals for our policy and b) it’s not at all obvious that he’s been closely following what’s going on with the agency. After his flight, almost four decades ago, he became almost a recluse, returning to Ohio to teach engineering, and offering little in the way of interviews. In any event, he decided (unwisely, in my opinion) to weigh in on the current NASA transition controversy:

Your article indicated that President-elect Barack Obama’s transition team “faces a tough early choice between extending the life of the aging space shuttle and accelerating its replacement.”

I certainly hope that isn’t accurate, in that the transition team should play no part in such decisions. While these men and women are experienced and enthusiastic space program veterans, they are neither aerospace engineers nor former program managers and cannot be sufficiently knowledgeable to make choices in the technical arena.

The transition team does have the responsibility to collect information to assist President-elect Obama in understanding the issues and decisions he will be facing. The making of decisions of such import, however, is the responsibility of the president and should be guided by the best advice from the most able and skilled experts on the subject.

I think that Professor Armstrong has the wrong take on this. No, the transition team won’t, and shouldn’t make such a decision (if for no other reason than it lacks the statutory or constitutional power to do so — its membership has no official government role, nor is it compensated). However, as he notes, they are collecting information to assist the incoming president in making such a decision, and that includes gathering “the best advice from the most able and skilled experts on the subject.” I’m curious as to why he thinks that they are not doing so. Does he think that this team will go through one exercise now, to no useful purpose, and then the president will later take the time to repeat it, this time “gathering the best advice” as opposed to whatever it is he thinks that they are currently doing? Clearly, they are gathering information, integrating it, and preparing a set of recommendations for the new president. As they should be.

But the next part shows that he has not been closely following what’s going on with NASA lately:

He should have no difficulty receiving high-quality information from NASA. Engineers are painfully honest and insist on presenting any assumptions used in their decision process. Therefore a conclusion can only be challenged when an erroneous assumption can be identified. Because this approach is somewhat unfamiliar in business and politics, its importance is often overlooked.

This is a nice, ivory-tower view of engineering and engineers, and I have no doubt that this is exactly what Professor Armstrong would do were he asked. But it is not what NASA has been doing. We have yet to see a full accounting of the sixty-day study that resulted in ESAS (including assumptions), so apparently NASA management either aren’t engineers, or they are not conforming with the good professor’s idealized notion of how they should behave.

A great deal of thought and analysis has gone into NASA’s program to return to space exploration as the principal focus of the agency. The breadth of NASA’s creative thinking was limited by the funding constraints, and compromises had to be made. Even so, the agency has fashioned a challenging but credible program to return to the moon and go on toward Mars.

How does he know this? Seriously?

Does he have access to the reports and analyses that have been denied to the rest of us? How does he know that the “compromises made” were a result of funding constraints, as opposed to political ones, and personal prejudices (or worse, conflicts of interest among the principals involved)? Is he just assuming that it’s the case, because he doesn’t want to believe otherwise about the agency that allowed him to be the first man to walk on the moon four decades ago?

And what does he mean by “credible program”? That if you put enough time and money into it, you can get it to fly? Sure. But that’s not the criterion. The criteria were supposed to be “affordable and sustainable” (not to mention supporting national security and commercial activity) and he hasn’t made the case for that (of course, he hasn’t made the case for the “credible” part, either, other than assertion).

I’d like to believe with him that NASA has the talented leadership, and has done the analyses, and has offered them up freely, with assumptions, to the transition team. But I’ve seen little evidence of it. This letter reads less like serious policy analysis (since he provides no specifics as to why he finds the program “credible”) than motherhood and wishful thinking in the service of the agency for which he worked so long and well, and with which he achieved so much.

Of course, NASA management wasted no time in making sure that everyone at the agency was aware of Professor Armstrong’s statement of support. And by sheer coincidence, the administrator has come out with a new book on his own laudatory leadership in space.

What we have here is an unseemly, pull-out-all-the-stops campaign to politically influence the incoming administration via public pressure (including pressure on agency employees via emails from the administrator’s wife). Mike Griffin should say something immediately to denounce and shut down this activity. If he does not, that in itself would be sufficient reason to replace him, were I the incoming president.

[Update a while later]

Keith Cowing is reporting that the letter was written for Armstrong by NASA. That wouldn’t be hard to believe (at least based on the wording). I think that it’s a little sad, though, that Professor Armstrong would allow his name to be used in such a way.