Tag Archives: science

582. Newtonian Nukes

Everybody who read the last generation of science fiction juveniles before Apollo knew Newton’s third law:

For every action, there is an equal and opposite reaction.

The demonstrations in popular science books of that same era usually went something like this: imagine a person on a frozen pond wearing ice skates, throwing bricks. Every brick he throws will move him backward. If we could ignore the friction of skates on ice, it would be proportional. That is, if a hundred pound man  . . .

Okay, side issue. Most Americans back then, and even today, don’t think in kilograms or kilometers, nor distinguish mass from weight in everyday thought, so . . .

If a hundred pound man throws a one pound brick at ten miles per hour, it will propel him backward at one tenth of a mile per hour. 1 times 10 = 0.1 times 100. We are ignoring friction from the ice, the atmosphere, and probably a bunch of other things.

So, if you want to go faster, throw more bricks, right? If you throw a thousand bricks, you should be able to go pretty fast, right? Wrong, because the first brick your throw in the new scenario will have to move not only the hundred pound man, but also the other 999 pounds of bricks.

Increasing the amount of fuel carried quickly brings about diminishing returns. More fuel alone is not the answer.

In a Newtonian scenario, the faster the propellant leaves the rocket engine, and the more propellant you use, the faster you can go. LOX and LH are probably near the practical  maximum for propellant speed by chemical reaction. The logical next step would be to use a non-chemical energy source to activate our propellants, such as a nuclear powered rocket. Even that won’t get us to the stars, but it makes sense for travel inside the solar system.

Before Apollo, everyone who read science fiction knew that, which is why the Scorpius and her sisters in the Rip Foster book are nuclear powered. So were the ships in Bullard of the Space Patrol, a marvelous fix-up novel by Malcolm Jameson that no one remembers today. So were the ships in the Dig Allen series (1959 – 1962), six great but forgotten novels, and the ships of the Tom Corbett books, which were not so great and are not completely forgotten.

Star Trek put all these early concepts out of business. Warp speed was a necessity for roaming the galaxy, but it made nuclear rockets look old fashioned. I think that’s too bad. There is still room for them in science fiction, and certainly in real life.

I haven’t mentioned Heinlein yet. The Rolling Stone was nuclear, but he quickly moved on to torch ships, which had the capacity of total annihilation of matter. He never explained how that could be done, but the result would be “propellant” moving at essentially lightspeed. You can’t get faster than that without warp drive. His torch ships roamed the solar system and went on to explore nearby stars.

I stole that schtick for my coreships in Cyan, with a twist. See 23. Star Drives.

In a rational world — which we will probably never inhabit, but we can still write stories about — you would might use chemical rockets to get to LEO (low Earth orbit), nuclear powered rockets to zip around the solar system (fission powered if you were writing in the sixties, fusion powered if you were writing today), and “torch ships” to reach nearby stars. Beyond that, you would need FTL (faster than light) vehicles which, by our present understanding of the universe, are impossible.

Too bad about FTL, but why are we still using chemical propellants in the real world fifty years after Apollo? Fear of nukes, of course. There will be more to say about that on Wednesday.

Advertisements

573: Apollo 9: Full and Complete

Apollo 9 was the first mission to fly full and complete: Saturn V booster, CSM, LM, and lunar rated spacesuits. They weren’t going to the moon, but they were checking out all the equipment that would take astronauts there.

Jim McDivitt was Commander, David Scott was the Command Module Pilot, and Rusty Schweickart was Lunar Module Pilot. Those designations are a bit misleading. Flying any part of a mission frequently took all hands. It took two people to land on the moon and the Commander was the lead pilot with the Lunar Module Pilot in something like a co-pilot’s role.

This was to be the first flight by a full fledged LM. (By this time NASA had dropped the acronym LEM because the word excursion seemed frivolous, but civilians and the media still called it the LEM.) A LEM mockup had flown unmanned, but the LM that flew on Apollo 9 had been much updated since then.

Apollo 9 lifted off on March 3, 1969 into low earth orbit. The Saturn third stage and attached CSM and LM were then moved into a slightly higher orbit, where the CSM separated, reversed and performed its first docking. The multipart cone which covered the LM was jettisoned at this time. (See 569, and animation in the film Apollo 13). The Saturn V third stage separated at this time and the combined CSM and LM moved away.

The Saturn V third stage had it’s own work to do. It’s engines were fired again to change the orbit’s apogee (high point). Once apogee was reached, the engines fired again to achieve a solar orbit. This firing did not achieve its proper objective, so a third firing took place later. Practically speaking, this merely got the third stage out of the way, but it also gave NASA a chance to once again check the flight characteristics of the Saturn stage which would, on subsequent missions, place the Apollo mission on orbit to the moon.

Aside: if you plan to read more on these subjects you will run into the terms S-IVB, which is the designation for a Saturn V third stage, and SPS, which is the designation for the rocket engine in the Service Module.

Now the CSM was flying backward in orbit attached to the LM, and the LM had opened its struts to a landing stance. The CSM fired it’s rocket for the first time (docking had been done on maneuvering thrusters), raising the orbit and providing the first test for the main engine.

Aside again: this mission should have happened before sending a crew around the moon. Although most of the events of Apollo 9 were firsts, a few things like firing the CSM’s main rocket had already been done on Apollo 8. However, the ability of the linked-up CSM and LM to fly under power had not been tested before.

The next day, the CSM/LM made three more burns, changing orbits and testing the integrity of the CSM/LM connection.

On the third flight day, McDivitt and Schweickart (with backpacks) transferred from the CM to the LM by way of the tunnel between hatches. The day was spent testing out the LM, including a six minute burn of the descent stage engine. McDivitt controlled the last minute manually, throttling up and down and shutting off the engine, just as astronauts would do on a actual moon landing. All this was performed while CSM and LM remained linked-up.

The fourth day of the flight, McDivitt and Schweickart returned to the LM. Schweickart spent thirty-eight minutes testing his spacesuit outside the vehicle. He had also been scheduled to crawl over to the CM to demonstrate how astronauts could be rescued after returning from a moon landing, should the two craft be able to rendezvous, but not dock. Space sickness made this maneuver impossible, but everything in the hardware itself checked out.

On the fifth day of the flight, McDivitt and Schweickart entered the LM for the third and last time, and separated from the CSM.

That is fifty years to the minute before this was supposed to be posted, assuming that my math and data from several different sources were all correct. Great plan, but my internet went down for three days. If fact, this post is coming out about three hours late, but at least I made it before Friday slipped away.

The major test of the LM descent stage engine had already taken place on day three. Now, it fired twice, first to raise the LM’s orbit and then to make it more circular. This was done to separate adequately from the CSM.

The descent stage of the LM was now jettisoned and the ascent stage engine was fired for the first time. This burn moved the LM ascent stage to 75 miles behind and 10 miles below the CSM. Over the next six hours, the LM ascent stage achieved rendezvous and docking. The astronauts moved back into the CSM, and the ascent stage was released. By remote control, it was ordered to fire its engines one last time and burned up in the atmosphere. The descent stage remained in orbit until 1981.

The remainder of the flight was uneventful. The CM splashed down north of Puerto Rico. The SM burned up on reentry, as would all subsequent SMs.

Almost no one remembers Apollo 9. It wasn’t the first Apollo into Earth orbit and it never went near the moon. It was a working astronaut’s flight, one more incremental testing of equipment. But when it was over, everything was ready for the moon landing.

Well, almost everything. There was still the matter of maneuvering the LM downward into a gravity well and out again, and the matter of getting good enough close-up views of the moon’s surface to be sure a landing could be done. Those would be the task of Apollo 10, in May.

One last aside: The April issue of the magazine Astronomy has interviews by the astronauts of Apollo 9. It just came out and I didn’t have time to read it before posting this.

550. CSM and Friends

The moon bound Apollo missions sent three things along, a LEM, a Command Module, and a Support Module. Apollo 8 was the only moon bound launch that didn’t carry a LEM, so we will save it for later. CSM was the common abbreviation for the linked Command Module and Support Module. The photo at the top of this post is a CSM.

In the original Mercury spacecraft, (shown here) the single occupant was in a closed space with all his supplies of air and, on longer flights, water and food. Flights were short and maneuverability was minimal. There was no need to store large quantities of fuel or oxygen. The retrorockets which burned to return the craft to earth were outside the vehicle and behind the heat shield; this was also true on the Gemini craft.

On Gemini flights, the ability to maneuver was critical. Gemini was the program in which astronauts learned how to rendezvous and dock and how to perform space walks. (EVAs; extra-vehicular activities) Gemini was also designed to test the effects of long term weightlessness. There was a need to store large quantities of fuel and oxygen, so a section was added between the crew cabin and the heat shield. It was not accessible from the crew space. You can see it in the silhouette of the Gemini spacecraft shown here.

Gemini could not contain both enough oxygen for very long missions and enough fuel for major maneuvering. Long missions were loaded up with oxygen, but little fuel. Rendezvous and docking missions were shorter and loaded up with fuel.

The trip to the moon would take plenty of breathing oxygen and maneuvering fuel, and a lot more besides. All this, and fuel cells for electricity, were crammed into the Support Module. It also had to act as another stage in the Saturn rocket. It had to have a large engine and fuel supply to use while entering lunar orbit, and when exiting lunar orbit to return to Earth. A comparison of the three photos will show that Mercury and Gemini had only retrorockets for return, strapped outside the heat shield, along with maneuvering thrusters you can’t see in the pictures. The bell of the CSM’s large rocket is clearly visible.

With Apollo, the heat shield was moved back to the base of the crew space. The Command and Support Modules were designed to be separated just before reentry. The Support Module burned up in the atmosphere while the Command Module was slowed by its heat shield before landing by parachutes.

This poster from NASA shows all three spacecraft side by side, at scale, with the LEM thrown in as a bonus.

We’ll look at the Apollo 8 mission itself on Wednesday.

495. Everybody, Two Jobs

Everything about Cyan was designed to give a picture of what might actually happen in the early days of extra-solar exploration. No ray guns, no hovercraft of the Marty McFly type, but hovercraft in the sense of ground-effect machines instead. Some of the technology I chose to give my people was not too far advanced over what we have here, early in the millennium. Why? Because if you are light years from home, you want your gear to work. It is not particularly important that it be up to date, but it needs to be indestructible. (see 253. Handgun Accuracy)

They walked a lot on Cyan. Feet don’t need new batteries.

In real exploration, you can’t expect everybody to survive. That means that you don’t want just one medic, or pilot. Someone has to be ready to step up in case of tragedy, and that needs to be planned in advance.

Which brings us to today . . . I mentioned last week that I have been cleaning out a house I used to live in. Today (May 11, actually, since I write these things ahead) I found an old ms. of Cyan with some notes I hadn’t seen in years.

I wrote the first half of Cyan on a typewriter. Go google it; it’s a crude instrument from ancient days. You actually had to spell words right without spell check, and if you lost something, it stayed lost.

That is why I am posting this now. I had intended to talk about this during the run-up to the publication of Cyan, but I didn’t want to trust my memory for details. Now I have the details right in front of me on a sheet of paper I typed up decades ago.

Except for Keir, everybody on the roster of the starship Darwin had a specialty, and one or more back-up specialties. Here is the list, alphabetically.

        Stephan Andrax    captain (spaceside) – astrophysicist
        Debra Bruner        microbiologist – astronomer – medic
        Petra Crowley       geologist – soils scientist
        Keir Delacroix       groundside crew leader – generalist
        Viki Johanssen      anthropologist – paleontologist
        Gus Leinhoff         zoologist – biochemist – medic
        Leia Polanyi          paleontologist – geologist
        Ramananda Rao  meteorologist – cartographer – geologist
        Tasmeen Rao       first officer (spaceside) – pilot (starship and landing craft) – engineer
        Uke Tomiki           botanist – biochemist – medic

In fact, only weeks into their exploration, a tragedy forces two of the crew to take on the job of one who has died, with unforeseen consequences. You know what I’m talking about, or you will as soon as you download Cyan from Amazon.

In the original iteration of Cyan, the expedition was from a united Earth with crew members from many nations. Stephan and Viki were Scandinavian, Petra was Greek, Keir was French, Gus was German, Debra and Leia were American, Ram and Tasmeen were from Trinidad, and Uke was Japanese. That hopeful future died along the way. In the world that Cyan eventually came to represent, the ever voracious United States, following a world wide financial crisis, gobbled up Canada, Mexico and the Caribbean. The crew members were now all from the United States of North America, but with their various ethnic backgrounds intact.

I like the idea of a peaceful, united world, but even when I began Cyan, America looked hungry. Today — well let’s not open that can of worms. Let’s just say that the less than peaceful Earth that ended up in the novel Cyan represents another attempt at realism.

481. Asimov’s Good Life

I couldn’t sleep last night so I lay awake thinking of an article to write and I’d think and think and cry at the sad parts. I had a wonderful night.
                         Asimov, from It’s Been a Good Life, p. 157

When I was new to reading science fiction in the early sixties, Clarke, Heinlein, and Asimov were everybody’s big three. Bradbury was in the next rank, but not for me. I found him unreadable. Andre Norton was still out in the cold for most people, but she, Clarke, and Heinlein were my personal big three. Asimov didn’t make the cut. I read a few of his novels, didn’t like them, and moved on.

Recently I ran across his summary autobiography, It’s Been a Good Life, edited by Janet Jeppson Asimov. It reminded me that I knew very little about the man, so I took it home.

Asimov has three full autobiographies, and a list of publications that goes on for eighteen closely packed pages. After his death, Janet Asimov published autobigaphical excerpts under the title It’s Been a Good Life. At 238 sprightly pages, 98 percent by Asimov himself, it was just right for someone who wanted to be fair to an author who is an acknowledged master.

Searching my memory and his bibliography, I found that I had read four of his novels: Lucky Starr and the Moons of Jupiter, The Stars Like Dust, and a couple of his early robot novels, each only a few years after they were published. I thought the first two were just adequate and the robot novels were dull. By the time I got to Foundation, I decided to skip it, along with anything else he might write. My local county library was full of science fiction I enjoyed, so why bother with Asimov.

It occurs to me now that might have been an error.

Asimov says (p. 143) The 1950’s [were] the decade of my greatest science-fiction triumphs, [but as] the 1950’s ended, I [ended] most of my involvement with the field. (see below)

From 1960 onward, Asimov wrote everything on every subject. It seemed to me that he had written every third book in the library. I dived into one or another from time to time doing research for my own writing. They were accurate, easy to read, and cursory, which is exactly what they were supposed to be.

When the novel The Gods Themselves came out in 1972 it was his first SF novel in fourteen years. (Not counting one novelization of a movie.) He had gone from SF novels, to non-fiction, then back to SF novels as a more mature writer. That was a biographical arc I couldn’t appreciate when I was first reading him as a teenager, for the simple reason that it had not happened yet. When it did, I had already lost interest. Not trying his new works, given his reputation, was certainly my mistake

By the eighties he was writing SF novels and winning awards once again. In 1989, he wrote Nemesis. He said this about it, “My protagonist was a teenaged girl and I also had two strong adult women characters. I placed considerably more emotion in the novel than was customary for me.” That sounds more my style, since lack of emotion was my complaint about his early work. I think I’ll check it out.

One last note for writers and would-be writers: This book is a treasure trove. I agree with pretty much everything he says about writing, but go read it from a man with far more credentials than I have.

=======

The brackets in the quotation are from Janet Asimov. She uses them to give context and continuity to excerpts which would otherwise be unintelligible. It is competently and smoothly done.

=======

Full disclosure time: After completing this post, I obtained a copy and read the first few pages of Nemesis. Sorry, I still don’t like Asimov’s writing style, but that’s all right. Not everybody likes Shakespeare, either.

477. They Never Flew (2)

 

NASP

Continuing from 472. Teaching Space and 474. They Never Flew (1), this post will discuss three manned space programs that never happened.

Eisenhower, Kennedy, Johnson, and Nixon were the presidents who took us into space. Whatever you think of any of them, they will always have that marked down on the positive side of their ledger.

Other presidents aspired to join them. How much of their thinking was patriotic for America, patriotic for all of mankind, or pure political calculation, is way outside the realm of my knowledge. I’m going to give them all benefit of the doubt and just talk about the programs themselves. You can spin motives any way that suits you.

Regan proposed NASP, the National AeroSpace Plane, also called the X-30. In his 1986 State of the Union, he said that we should produce a vehicle which would be “a new Orient Express that could, by the end of the next decade, take off from Dulles Airport and accelerate up to twenty-five times the speed of sound, attaining low earth orbit or flying to Tokyo within two hours.” It was an exciting idea, coming out of DARPA where it had begun as a black project.

NASP was supposed to produce two prototype planes, but neither was ever built. That doesn’t mean that it was a political scam. The technological difficulties of the project were staggering.

In detail, NASP was cutting edge. As an idea, the horizontal launch of a spacecraft was old in science fiction. There it was usually accomplished by electromagnetic technology, with ground based and powered launchers and only maneuvering fuel on the vehicle itself. See many early Heinleins, especially Starman Jones and The Moon is a Harsh Mistress.

One reason rockets take off vertically is to get mostly out of the atmosphere before achieving speed. That way, massive friction is only a reentry issue, when it can be used to advantage.

NASP was a jet, not a rocket. It had to operate primarily inside the atmosphere. This has the advantage of avoiding carrying oxidizer, but has a series of disadvantages. Friction heating is an obvious one. In addition, its engine would have to operate in three modes — as a relatively conventional jet at takeoff, as a ramjet once sufficient speed had been achieved, then as a scramjet (supersonic ramjet) once it passed the speed of sound.

At that time, no one had successfully built a scramjet, and NASP didn’t make it happen. The first scramjet, the X-43, made a brief flight in 2001, eight years after NASP was cancelled.

No one has successfully built a skin that can withstand reentry level heating on a continuous basis, either. NASP was too far ahead of its time. I spent a few years explaining to my kids how it was supposed to work — before it didn’t work, and silently crept away.

Then came Venturestar, which, if it had been successfully completed, would have done what the Space Shuttle was originally designed to do. It was to be a vertically launched, completely reusable, single stage to orbit vehicle with a wider and more efficient lifting body that would have allowed it to land, in emergencies, on shorter runways than the Space Shuttle.

To do all this, it would require new and untested technologies, including composite material LH tanks, a new tile-free heat resistant skin, and an aerospike engine. The project was divided into two parts. To demonstrate the feasibility of the new technologies, a one-third size, unmanned model of the VentureStar, called the X-33 was to be built and tested, and only then was a full sized VentureStar to be constructed.

Things did not go well. When the X-33 was partially completed a version of its composite LH tank was tested and failed to hold pressure. Alternatives existed, but the decision was made to cancel the project. The funding for the X-33 was a complex mixture of commercial and governmental funds, and continuation depended on all parties agreeing. That didn’t happen. The Air Force was still part of the mix, as with MISS and the Dyna-Soar, as with the black missions by the Space Shuttle, but their request for continued funding was denied. The Air Force eventually got the X-37b instead. The X-33, and with it the VentureStar, disappeared. For a view that the cancellation should not have happened, click this link.

From the perspective of a science teacher, VentureStar had been a godsend, full of all the excitement the Shuttle and NASP had lacked. Once it failed, my kids had no future in space that they could personally dream about.

Then came Project Constellation. By that time, my days as a teacher were coming to a close, so I did not have to face the daunting task of generating enthusiasm for a cobbled up rerun. Ares I, the small booster, was built out of Space Shuttle leftovers and Ares V, the large booster looked suspiciously like a Saturn V reboot. The Orion Crew Exploration Vehicle was an oversized Apollo capsule and the Altair moon lander was a LEM on steroids. Not only was Project Constellation going to do again what had been done forty years earlier, it was going to use essentially the same hardware.

I didn’t buy it. I didn’t try to sell it to my kids. It died four years after it was floated.

The future isn’t dead. The Space Launch System continues where Constellation failed and private enterprise has more strongly entered the mix. Today’s science teachers should be able to say, “You might be the first person on Mars,” with a straight face. I continue to hope.

474. They Never Flew (1)

Continuing from 472. Teaching Space, this and the upcoming April 5 post will discuss the manned space programs that never happened.

Wikipedia lists seven manned pace programs which were canceled before they were launched, but this list is only technically accurate.

MISS, Man in Space Soonest, was a project from the early days when the Air Force planned to dominate space. The preliminary work was transferred to NASA when it was formed and became Project Mercury. Technically, MISS never flew; looked at more reasonably, MISS became Mercury, which was quite successful.

Dyan-Soar was a follow up Air Force project which planned to put a winged craft into low earth orbit, and subsequently turn that into an ultra-long range space bomber. It was contemporary to Project Mercury. There was not enough money or will to keep them both, so Dyna-Soar was cancelled, only to be reborn, in a manner of speaking, as the Space Shuttle. For details see 342. Dyna-Soar.

The Manned Orbital Development System, Blue Gemini, and the Manned Orbital Laboratory were successive names for the same secret project, designed to use modified Gemini craft to service an early one-use space station as an orbital observation post. It got to the point of one unmanned launch before being cancelled. It was made obsolete before it went into service by advances in unmanned reconnaissance satellites. For details see 256. The Space Station that Never Was.

By the time I started teaching, the era of manned space exploration was over, but there were plenty of manned space flights. The shuttle had 135 manned missions; Mercury, Gemini, Apollo, Skylab, and Apollo-Soyuz combined had only flown 35 manned mission. However, none of the Shuttle flights were explorations.

The early Shuttle flights were exciting and technologically innovative, but they only went where Mercury had gone two decades earlier. The flights quickly became routine. They were dangerous — Challenger and Columbia proved that — but danger alone does not bring excitement. Commuting on a freeway is dangerous, but only exciting during moments of imminent disaster.

The Space Shuttle was supposed to be a cost saving way to space, but it proved quite expensive. It was supposed to be reusable, but that turned out to be only partially true. It was supposed to be single stage to orbit, but it never was. Each launch had four components, not one. The fuel tank was only used once. The two solid fuel boosters had to be recovered from the ocean and refurbished each time. Only the orbiter was fully reusable, and it had massive problems with failing tiles.

A vast number of its flights were spent building and maintaining the International Space Station. Many scientists tried to stop the construction of the ISS, claiming that not much science would be done there, but the cost would cripple other exploration. They were not listened to. Politically, the ISS was a demonstration that the cold war was over and the US and Russia were now pals. You know how well that turned out.

From the viewpoint of science, plenty of exploration was going on in my kids’ era, but it all involved unmanned craft. From the viewpoint of a teacher trying to excite middle school kids, a Mars rover landing was great, but if it couldn’t be followed up by a statement like, “You may go there someday,” if fell relatively flat. None of the kids I taught in the eighties are going to Mars; by the time anyone gets there, those kids will be retired, and they knew it at the time.

The only manned space craft of my kids’ generation was the Space Shuttle, and it was only flying to low earth orbit. A lot of good science got done by the shuttle (and a lot of political nonsense) but it wasn’t the same. Mercury, Gemini, and Apollo were like going down the Amazon in a dugout canoe, with adventure around every corner. The shuttle was like driving to Sacramento on Highway 99. Dangerous, yes, but not exciting.

But every year there was hope. New manned space projects kept being proposed, and I studied all of them so I could teach my kids something that would excite them.

Regan had NASP; Clinton had VentureStar; Bush Two had Project Constellation. We’ll look at all three on April 5, and try to recapture the genuine excitement they generated, before they faded into history