Planetary Radio: Space Exploration, Astronomy and Science - Building the J-2X Rocket Engine for the Return to the Moon

Episode Date: November 5, 2007

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Building the rocket engine that will take us back to the moon, this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan. And are we jam-packed this week? We'll hear from John Villia, the man from Pratt & Whitney Rocketdyne, who is in charge of getting the J-2X rocket engine built.

Emily Lakdawalla will tell us what we know about asteroids that can and do smack down on Mars. Not much, really. And then Bruce Betts will join me for a look at the night sky and news about our expanding 5th anniversary prize package. Now you can win more than a Mars meteorite fragment.

Just time enough to mention this week's top story. Kudos to spacewalker Scott E. Parazynski, who completed one of the most challenging and dangerous repair jobs ever. Scott successfully mended a torn solar array on the International Space Station. He also managed to avoid going down in history as the first electrocuted astronaut. We'll put a link to the story at planetary.org slash radio. Back in a minute with John Villiam, here's Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, We hear a lot about the hazard from near-Earth objects.

Is there such a thing as near-Mars objects? Although there probably are asteroids whose orbits will eventually intersect with Mars, there is no one in the astronomical community who is specifically looking for potential Mars impactors. The scientists who are worried about Earth impactors do check the near-Earth asteroid population to see if they have close approaches to Mars or other planets, because a close approach to the gravity well of a planet will change the orbit of a near-Earth object, making it more or less likely to strike Earth in the future.

But potential Mars impactors that are not on Earth-crossing orbits are, by definition, more distant from Earth than near-Earth objects, so they are fainter and therefore not as likely to have been discovered unless they are quite large. The next Martian impact will almost certainly be from an object too small to be discovered with current telescopes. In fact, the Mars impactors that we should be most worried about may be practically impossible to discover before they hit. Stay tuned to Planetary Radio to find out more. John Villia is Pratt & Whitney Rocketdyne's program manager for the J-2X. John and his crew are on a tight schedule set by NASA for development of this latest edition of a series of rocket engines

that once took us to the moon and promises to do so again. I got him on the line from his Southern California office just a few days ago. John, thanks very much for joining us on Planetary Radio, and congratulations to you and Pratt & Whitney Rocketdyne for getting this contract a few months ago that is intended to take humans back to the moon. Yeah, we're proud to get the work, and we're excited about it. Tell us why, first of all, liquid-fueled rockets that really, in their basic design, are not so different from

what Robert Goddard came up with so many years ago. Why are they so good still at getting us into space and then getting us around places once we're up there? Well, there's a couple of features that are nice about them. They give you pretty good performance. For any chemical propulsion, the liquid engines give you better specific impulse or miles per gallon type performance than the solids do. The other thing that's nice about them is you can throttle them and shut them off when you want to. The alternatives generally, like a solid, would require you light them, you stand back, let them run their course, and then they're done when they're done. Was I accurate in what I said that really, if you get down to the basic design,

Was I accurate in what I said that really if you get down to the basic design, they haven't changed that much since Goddard's days, although the technology has gone light years? I think they're analogous to automobile engines. The original early automobile engines were pretty much simple piston internal combustion engines, and since then they've become far more sophisticated, more efficient, more reliable, but they're still the basic cycle. The same is true for these engines. You've got quite a legacy just within this series of engines, the J-2, which took us to the moon before.

Yeah, the J-2 was used on the second and the third stage of the Saturn V launch vehicle. You know, there were five of them on the second stage and then one of them on the third stage, and they were real workhorses for the whole lunar program. Tell us a little bit more about the history of this engine, the J-2 series. It's even, I guess, components of the engine. I mean, I saw that just the turbo pump portion of this engine also saw use elsewhere. Sure. Back in the 60s, while they were doing the lunar missions, the engineers that had developed them were on hand to support the lunar missions.

While they were doing that, they were also working on an upgraded design called J-2S for Simplified. And the J-2S was really a completely different engine. It was more thrust, better performance, and they upgraded everything they learned while they were developing the original J-2. Well, they never upgraded the Saturn V, so the J-2Ss just went into mothballs. In the 90s, when we were working on the X-33 program, we took the turbo pumps from the J-2S and the gas generator from the basic J-2 and married them with an aerospike thrust chamber, which is a really new type of rocket engine design altogether. And the aerospike, I think the big deal about that

is, I mean, it looks very different from the bell-shaped combustion chamber we're all used to with rocket engines, but the hope was that it would be more efficient both in atmosphere and out of it or something like that? Right, because the aerospike, the fire is on the outside of the nozzle, if you will. It can expand or contract depending on the atmospheric back pressure, so it's more efficient along more of the trajectory of the vehicle. And, you know, to kind of picture what they look like, if you ever see the Star Wars movies, the Millennium Falcon on the back end of that, the engine on the back, back is very much like an

aerospike. I never thought of that, that when that thing lights up blue, we're looking at aerospike. I don't know if it was in the future or a galaxy long, long ago, but maybe there were Pratt & Whitney turbopumps in there. Perhaps, but it certainly is an easy way to visualize what an aerospike would look like when it's integrated with the vehicle. Let's talk about the turbopumps, because I mean, I remember reading about these as a kid, reading about the Saturn V, the J-2, and, of course, the mighty F-1 that no rocket engine since has equaled. And really, it seemed that these pumps were the most amazing part of the technology. I don't know. You build them. Do you agree?

Yeah, they're very much the heart of the engine in the sense that they really have a tough job to do. Pumping hydrogen is one of the hardest things that we know how to do because the amount of work that requires to pump hydrogen is more than any other liquid because the density of the liquid that you're talking about requires more work. Hydrogen's very undense, meaning that it's got about half the density of balsa wood. If you were to have a pool of liquid hydrogen throw some balsa wood and it would sink like a rock so it takes up a lot of space and it's very lightweight but pumping it it's like pumping almost like pumping air it's

real tough as a liquid to pump and so they have to get very sophisticated it's also complicated by the fact that it's the second coldest liquid. So the pump end is really contracting, getting cold, while the turbine end is hot. It's hotter than an oven. And so you have to kind of keep the cold end cold and the hot end hot. And a lot going on with all the rotating components that are connected while they're trying to shrink in different directions. How much hydrogen do you need to move through this to have the J2X do what it's supposed to? Well, let me think. It's about 100 pounds per second. And given that it's very non-dense, it really is a lot of volumetric flow rate.

How fast is that pump spinning? This pump is designed to spin at about 30,000 revolutions per minute. So one of the challenges is just figuring out how to make it hold together, keep from flying apart. Absolutely. We set some of the thing that limits the velocity in which it rotates is how well the pumping portion can keep from basically exploding due to centrifugal forces. So that's what sets the speed. And then you, of course, size everything around that speed limit. What sets this newest version of the J2 apart from both the original and the J2S, which was already, as you said, an improved version of this engine?

Well, this one does two things. This one gives you 294,000 pounds of thrust. The original J2 gave you 230,000 pounds of thrust, and the J2S was 236,000 pounds of thrust. So at 294, it's a lot of extra thrust, and that allows you to lift a heavier payload given where they light this thing off. The other big improvement is in specific impulse, and that's how many pounds per second of propellant you need to put into an engine to get a pound of thrust. And so when you're talking about an engine like the original J-2, it had a measure of 425. So for every pound per second of propellant you put into it, you got 425 pounds of thrust. Okay, our engine will give you 448 pounds of thrust. And every little bit counts when you're trying to get something out of Earth's gravity well.

Exactly. And it allows the propellant tanks to be a lot smaller for doing the same job. And so this specific impulse that we're getting is really a record for this class of engine, which is a gas generator type engine. That's John Villia, program manager for the J-2X rocket engine. He'll tell us more when Planetary Radio continues. I'm Robert Picardo. I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society

to become part of the real adventure of space exploration. The Society fights for missions that unveil the secrets of the solar system. It searches for other intelligences in the universe, and it built the first solar sail. It also for other intelligences in the universe, and it built the first solar sail. It also shares the wonder through this radio show, its website, and other exciting projects that reach around the globe. I'm proud to be part of this greatest of all voyages,

and I hope you'll consider joining us. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio. Welcome back to Planetary Radio. I'm Matt Kaplan. My guest is John Villia of Pratt & Whitney Rocketdyne, where he is in charge of creating the J-2X rocket engine, a key component in NASA's Constellation system that will take humans back to the Moon. take humans back to the moon. I have to think, without having read this, that in the, well, boy, it's going on 50 years since the J-2 was committed to, that there have also been enormous improvements in material science and maybe also in how you control these engines?

Absolutely. One of the things we've done is we've gotten rid of some of the parts that were tough to work with. Aluminum beryllium was what the turbopump housings were made of. We got rid of the beryllium because whenever you machine that and handle that, you had to do it in a controlled atmosphere because beryllium is toxic. And so we've gone to a non-toxic materials base, which gives a similar strength and reliability. For the electronics, well, they had some awfully primitive electronics. The Moon mission is amazing when you think about it,

because any Palm pilot today has far more computing power than the total lunar mission. And so we're taking advantage of the computing power we have to do better, more precise controls, better health monitoring as we run the engine. Tell us how this engine sort of fits in, if you will, to the Ares vehicles. Yeah, this is actually the second stage of both the Ares I and the Ares V. The Ares I is the crew launch vehicle launcher. Its first stage is a solid propellant rocket motor, very much like they use on the side of the shuttle. They've just lengthened it, and they have a fifth segment. There's four segments on the current shuttle. So that five-segment solid is the first stage. We sit on

a liquid stage on top of that. And then the crew vehicle, which is called Orion, sits on top of the second stage. So it'll look very much like a traditional rocket with a capsule on top. Our J-2 engine is buried at the bottom of that second stage. And so on the Ares V, it's slightly different. There's five liquid engines on the first stage, along with two strap-on solids on the side of that first stage. We're again on that second stage, but we're a larger second stage. Because on the cargo launch vehicle, we fire to get the payload into orbit, and it sits there for a while and waits for the crew to join up with it. When the crew has joined up, everything's checked out, ready to go. Our engine will then fire once

more and lob everything towards the moon. You know, what's interesting about that model, I remember again as a kid giving away my age, reading books by some of the early engineers, rocket engineers, von Braun and others, where they used exactly this kind of model, a heavy lift vehicle that put a whole bunch of stuff up there, and then you boosted the humans up to take their place and go to the moon or beyond. Yeah, it's really a safer way to go because you can put the payload into orbit, check it out remotely before you risk people on a launch, and then once everything is good to go, then of course you put people into

orbit, rendezvous, and off you go. Do I have it right, the first stage of the Ares V vehicle, is that still slated to use the Space Shuttle main engine derivative? No, actually the first stage of the Ares V will now use the RS-68 engine, which is used on the Delta IV launch vehicle. And so the Space Shuttle main engine, which is still, oh, what, I guess about not quite a third more powerful than the J-2X, which is also built, I believe, by Pratt & Whitney Rocketdyne, that one is no longer part of the program. No, it's not. It's been replaced by the RS-68, which we build as well.

And it's 650,000 pounds of thrust. The shuttle is about 425,000 pounds of thrust, depending on its throttle setting. But the RS-68 is 50% more thrust than on a first-stage booster. That extra thrust is a big deal because it lifts a lot more per engine. With five RS-68s on the bottom of that and then two five-segment solids, that's really quite a brute. It can put a lot into orbit. So where are you now in this program? Are things on track?

And does it look like, at least as far as the Rocketdyne contribution, that we're on track for the moon? We are on track. It's surprising. We've been working on this engine for coming up on two years under various contractual mechanisms. We're actually still on schedule to get our first engine in a test stand when we first predicted we would. And that'll be sometime at the beginning of

2010. So really, we're right on top of it. And I'm thinking that it might be kind of fun to pick up some audio from that. Will there be press coverage of that event? Yes, there will be. And where is it going to take place? I know that really a big part of the history of Southern California, or at least the space program in Southern California, was the testing of these engines up in the hills behind Los Angeles. That's where I started my career up at Santa Susana. That was a fun time. But we'll be doing our testing at the Stennis Space Center in Mississippi. We have most of the active test stands in the nation going on there right now. And we've already taken over the A1 test complex. We did that about a year ago.

We've refurbished it. We've installed this power pack into there, and the testing is getting ready to go forward. We're about to start testing the power pack portion of our engine. That's coming up here later in November, so we're looking forward to that. You've been in this game for quite a while, the purest form of rocket science, I suppose. I've been at this for about 25 years now, and this is a great job. I can't imagine having more fun at work than this job.

So is the J-2X an engine that you foresee serving the needs of the United States, the space needs of the United States, for a long time to come? Absolutely. It's going to be the workhorse for a long time to come. And one of the reasons why they selected it for both the Ares I and the Ares V is it's one of the few engines that can do the whole mission. It's going to be the workhorse for exploration. We're told we're on the critical path now for getting humans back into space on the Orion. And so we're working to make sure that our schedule never slips. And it's kind of a pressure cooker situation. And it's kind of a nice place to be because we do get all the attention

and all the help we need when we need it. But so far, the engine's looking like it's really going to be a workhorse for decades to come. With luck, in a few years, you're going to be in a place where you've been before, and that is watching humans basically sitting on top of your engines on top of a brand-new vehicle. That has to be some nail-biting there, but it has to be enormously rewarding as well. It is, and I think that we're making sure that we do all the right things right now because you can't fix it later. You've got to put the fixes in right now. And so everyone's being reminded of that.

We have astronauts working with us on the program, and they're constantly here to make it clear to us that there are people whose lives depend on this. John, we're out of time. Thanks very much for joining us. And good luck with that test firing and everything that still is ahead of us for the J-2X program. Thank you very much. that still is ahead of us for the J-2X program. Thank you very much.

John Villia is the program manager for the J-2X rocket engine program that will be on the bottom of, as you heard, some of the stages of those Ares vehicles that will take us back to the moon and, with luck, beyond. He is at Pratt & Whitney Rocketdyne, the company that has built so many of the engines that have powered this nation's effort to explore space. We'll do a little exploring of space of our own as we do every week with Bruce Betts in this week's edition of What's Up.

That's right after a return visit from Emily. I'm Emily Lakdawalla, back with Q&A. We don't currently know if any of the thousands of asteroids that we have discovered is on a collision course for Mars. Pretty soon, a new generation of asteroid-hunting telescopes will start operating, which should yield the discoveries of many thousands more Mars-crossing asteroids, and scientists will probably start checking to see if any of them is likely to hit the red planet any time soon. We do know that asteroids strike Mars from time to time because Mars Global Surveyor discovered at least 20 new craters on Mars during its nine years of operation in images

covering only 30% of the surface. In the future, if there are permanent human bases on Mars, it will become very important to understand the Mars crossing asteroid population. In fact, future Mars residents face a much larger threat from asteroids than Earth residents do, because Mars's thin atmosphere is not nearly as good a shield against small asteroids as Earth's is, and there are a great many more small asteroids than there are large ones. Future Martian bases may have to be sited in tunnels or caves underground to avoid the threat of rocks falling from the skies.

Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. From Studio B at the Planetary Society and not quite live, this is What's Up with the Director of Projects for the Planetary Society, Dr. Bruce Betts. Studio B, that being Emily's office because she's not here today. Yeah, I got kicked out of Studio A because Lou's being interviewed by Croatian TV. Tell us what's up. But we have good stuff.

We have better stuff. First, we have to... I can't say that. First, we talk about that comment you brought up last week. I was blitzed from travel. I hadn't seen anything. Didn't know it was out there. And so, basically, I was a raving lunatic.

I did tell people about a real comment that was out there. Elementary, my dear. I did not tell them about the one you were talking about, apparently. I told them about Elonio's comet that indeed is visible in binoculars, but of course, now I know and many others and you with your pulse on the finger of observational astronomy knew that there has been a naked eye outburst which sounds, god that sounds painful, of Comet Holmes. A million times as bright as it was before the outburst. It was a freaky little thing.

It was a dim telescope object and then had this massive outburst, shed a whole bunch of stuff, that's the technical term, and it's been shining as brightly as uh like magnitude three or a little brighter magnitude two and a half not bad naked eye theoretically for a for a point object is magnitude six in a dark sky two and a half for a comet still may be tough naked eye in a lot of places because it's a fuzzball but you can go out there it is in uh perseus the best uh best way to do it is probably search Comet Holmes finder chart out on the web. Really freaky object.

Not a lot of precedence for this. Comets do outburst, but this visibility change is truly unusual. Well, Mercury is making a sad little showing these days. days in the glow of sunrise in the pre-dawn. You can look for it about 30 minutes before sunrise, just above the east horizon. And it's far to the lower left, a much brighter Venus, which you can't miss still in the pre-dawn, brightest star-like object. And then look above Venus and the brightest star-like object above that, which is much dimmer than Venus, is indeed Saturn. So a big party in the pre-dawn sky. You've got Mars in the evening sky.

I checked it out the other night, looking quite bright. Not Venus-like, but almost as bright as the brightest star in the sky. Not quite there. Rising in the mid-evening in the east, it's the reddish-looking thing. And we'll be high, high overhead before dawn. And we've still got Jupiter hanging out, getting very low in the southwest, west, just after sunset. Brightest star-like object there. So that's the planet roundup. We move on to random space fact.

I like the little chair squeak in the middle of that. I think you should keep that. Thanks. Oh, now it won't squeak for me. Mercury, of course, the speediest planet in our solar system, zipping around. And at its fastest, it goes around the sun at nearly 60 kilometers per second. Ooh, that's very fast, yeah. Zippy, I tell you.

I'd like to go that fast. Okay. Well, you're going, you know, a good fraction of that on Earth. Let's move on to the trivia contest. We asked you about Sputnik. What was the rocket? What kind of rocket launched Sputnik into orbit? How did we do?

Wow. What's really significant here is that people have caught on. They know that by entering during this period, including this, this is the very first contest, weekly contest, that makes the entrance also eligible for our fifth anniversary prizes. And sure enough, we have like tripled the number of entries. Pretty impressive. Getting hard to get through my inbox. But here you go. First time winner.

Interesting. Has been trying for a you go. First time winner. Interesting. Has been trying for a long time. Candace Murray. Candace Murray said it was the R-7 Semyorka, a NASA name SS-6 Sapwood. They come up with all these faintly insulting names for old Soviet rockets, of course. Soviet Union name 8K71. But basically, R7 is what virtually everybody came up with. Candice, you came through. We're going to send you a Planetary Radio t-shirt. Thanks very much. Indeed, the R7. You can actually trace the heritage of the Soyuz very directly, all the way back to that. When they find something that works, they stick with it. Yeah, yeah. They're still going. They're still launching them.

It's great. Somebody said one's going to launch down in Guyana. They're going to start putting them up from where they launch Arians. This is correct. Let's go on to the next trivia question because I know you have some more things to share with us. You betcha. What is the escape velocity from Jupiter? For Earth, it's about 11 kilometers per second to escape the

gravitational pull of the Earth. What is it for Jupiter? The nearest kilometer per second, let's say. Go to planetary.org slash radio to find out how to enter. And what else are they competing for? By entering this contest, they'll enter for a t-shirt. But what else? Oh, so much more. Because we are in the middle of taking entries that will also be up for that fifth anniversary contest that we're running. If you enter in this one, you will have that many more chances, one more chance, when we do our big drawing. I think it's the November 26th show, Monday the 26th, the show that begins to air that date. We already have told people that somebody out there is going to win a grand prize of a Mars meteorite fragment. It came today.

It's here. I saw it. Now, it's small because what do you want? It's a Mars meteorite fragment. We only have 30 small rocks from Mars in total. So if you get any piece, the profound thing is it's a piece of rock that came from Mars. Hello. It's a piece of Mars. It's a piece of Mars.

It's a piece of Mars. We already had one listener say that if he wins, he promises not to eat it. But you know what else I'm happy to say? Well, first of all, let's credit SpaceFlory.com. And our good friend Florian Knoller, who donated this, made it available for us to give away to you. If you check his website, you'll find that he has other stuff like this and all kinds of space memorabilia signed by astronauts and others.

But you know what also happened today? We have to also credit Vision Video Games because they have donated two copies of Space Station Sim 2.0. This is a sim game, a simulation game that lets you run your own space station. That's cool. Extremely cool. Space Review said

one of the best contemporary space program themed games I have ever seen and most importantly, it's fun. All credit to Space Station Sim at Vision Video Games. You can find them at vision- or vision-play.com

or just Google Space Station Sim if you're interested in looking this up. I have to read you this line from the back of the box for the game. It has all kinds of cool stuff that it talks about. It says, you can then create up to six crew members to perform experiments, repair equipment, and live

and love at 17,500 miles per hour. Emphasis mine. I have no idea. I haven't played it yet. It just came today. Rated E for everyone. That's right.

It's rated E for everyone, 10 plus. Lest you think otherwise. I don't think it gets into. It's because you focus on it. Right. All right. It's just my dirty mind. Yeah, okay.

But it really does look incredibly cool, and I'll have a better report next week. Okay, you come back with your review after doing your professional duty of playing the video game. You betcha. But we have two of these to give away to two of our lucky fifth anniversary winners. Faboo! Okay. Oh, by the way, you want to answer that question that Bruce just threw out there. By the 12th of November, Monday the 12th, at 2 p.m. Pacific. Now we're done. All right, everybody, go out there, look up at the night sky.

Think about Venetian blinds. Open or closed? Thank you. Good night. Someday I'll tell you about the concept I came up with with a friend in college. Venetian geese. But I'm not going to describe it on air. People will have to write.

He's Bruce Betts, the director of projects for the Planetary Society. He blinds us with science every week here on What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week..