DARPA and 100-Year Starships: Not so Fast

Credit: Adrian Mann, who does artwork for Project Icarus!

Recently there was a big flurry of stuff in the news about DARPA commissioning a "100 Year Starship Study." Tossed in amongst this was a variety of other stuff, like microwave beam-powered launch and sending humans on one-way trips to Mars. Naturally the media got this all backward and took it to mean that NASA was planning to send humans to Mars by 2030 - but leave them there. Which is rubbish, as at the moment NASA has no plan and no direction except to visit a NEO in the 2030s. Woo hoo.

The fact of the matter is, as the Tau Zero blog, Centauri Dreams confirms, is that DARPA is merely interested in setting up the business case for an organisation with developing deep-space flight as its goal (and presumably interstellar flight). It recognises that there are huge hurdles to overcome, and that the technological windfall might be very great indeed. Consider hibernation - which would be of enormous benefit in keeping critical patients alive until they can be treated.

Unfortunately, there's not even a hint of anybody starting something up seriously.

As the content of this (poorly maintained) blog attests to, I'm quite interested in interstellar travel and colonisation. I'd recently read Ark by the eminent Stephen Baxter, which dealt with an interstellar mission spurred on by a global flood (deep subterranean aquifers suddenly releasing their contents). I was so inspired by the description of the ship that I went back to the drawing boards of my own designs and started looking up papers on the subject. Now, Faster-Than-Light travel is right out - simply because nobody has any idea on how it might eventually come to light (no pun intended of course). And then there's the problem of how we might be able to power it - something like the total energy output of a galaxy to move one piddly ship? Then there's all the other problems - how do you make the warp bubble, the warp bubble destabilising, etc. etc.

Which brings us back to regular Slower-Than-Light travel, the capabilities of which are not very spectacular. It turns out that to get anywhere at a reasonable pace, heck, even to launch a decent-sized colony ship at Voyager II velocities, a prodigious amount of energy is required. How much?

Marc G. Millis of the Tau Zero Foundation has an interesting article on the arXiv preprint server, "Energy, incessant obsolescence, and the first interstellar missions", is quite revealing - and depressing. It puts into perspective the enormous energy requirements even modest STL requires. It's a lot of energy. Let's put it into perspective how much:

Eq. 1 Source: Marc G. Millis

That little e is the pesky thing that means the faster you want to go (relative to your exhaust velocity), the bigger your fuel load. Let's say you have a space shuttle engine which burns hydrogen and oxygen and gives you, oh, 4.5 kilometres per second (kps). You want to get into Earth orbit, about 9 kps. That 9 kps is your delta v, (the triangle with a v), and you put that over your exhaust velocity (vex) and you get e². Plug that into the calculator and you get 7.389. What this means is that your spacecraft is now 6/7 fuel load and 1/7 everything else. Basically a flying fuel tank. What it also means is that for your spacecraft to go at, say, 3% the speed of light, your exhaust must travel at 3% the speed of light (c). That's hard. Chemical rockets manage something like 0.001% c.

The second side of the equation is where it really stings. See that vex²? Multiply 3% c (9 million metres per second) by 3% c (another 9 million metres per second) and you wind up with energy levels in the range of kilotonnes and megatonnes per kilogramme. So, it pays to go bigger and slower. Doubling your exhaust velocity (and hence top speed) quadruples your energy requirement, whereas doubling your mass only doubles the energy. Putting a satellite in orbit requires something in the range of a WWII conventional bombing raid in terms of energy. Sending a teeny probe to Alpha Centauri at 3% the speed of light requires lots more energy. How much more? OK, let's break into the equation.

1/2m = 500kg (for a 1 tonne probe).
We'll assume the probe's delta V is the same as its exhaust - 2.7. Less the 1 = 1.7.
vex² = 8.1 x 10¹³

Putting it all together:
500 x 1.7 x 8.1 x 10¹³ = 6.885 x 10¹⁷ Joules. About 150 megatonnes yield (metric tonnes). By comparison, the highest nuclear weapon yield is in the region of 5.2 megatonnes per tonne. That's roughly 1000 Hiroshimas to get one tonne to Alpha Centauri in about 135 years. Double the delta v, however, and the energy requirement only goes up by 3.7. (the actual kinetic energy requirement is still the same). So it's somewhat more efficient to have a lower exhaust velocity and more fuel.

Millis compares energy used by space missions today with total world energy output, and compares energy growth with the energy required for an Alpha Centauri mission. It's rather depressing. Only by 2500 are we able to send such a probe to Alpha Centauri. And sending a 25 000 tonne colony ship on a millennia long journey to the stars requires more energy for a long trip than to actually send it on its way! (Best case scenario 2200). All of this dovetails with other authors' projections, economic, spacecraft top speed, etc. which puts the first possible interstellar colony ship in two centuries' time. Bummer. But it at least gives us some other numbers to play with, which I'll (hopefully) blog about over the next couple of weeks.

What it does show, though, is that big generation ships are likely to be available earlier than unmanned probes. And that a "space ark" is possible perhaps in one or two hundred years, if we throw enough money at it (which may only happen in case of impending global disaster). The (somewhat) silvery lining is that Millis considered the proportion of energy spent on spaceflight as a constant. With mass commercialisation, that number may well go up as a percentage. Much the way the energy spent on flight has gone from zero to becoming a major global warming problem...

1 point 3 BILLION internet users...

International companies have this going through their heads whenever they think of China: 1.3 BILLION customers, probably in a Dr. Evil voice.

From the outside, it looks fairly straightforward. But let's not make the mistake of thinking China is going to become a country of 1.3 billion Americans overnight. The average Chinese person in the city is making less than the South African minimum wage - about US$300 compared to US$400, and that's for a 40 hour week. Oh, there are plenty of white collar staff earning pretty well, but still below what South African equivalents are earning. They make up for this low wage situation with dirrrrt cheap products. Now, how is your average factory worker going to afford a PC which will cost one or two month's wages, even in dirt cheap China (even if you can buy a pirated copy of Windows 7 for 5 yuan)? Sure, you can use an internet cafe if you want.

Yet China has some 384 million internet users. This doesn't mean that 384 million people have computers and an ISP. In fact, in 2008, "only" 32 million PCs were sold. 102 million computers were in use, compared to 274 million in the US. That's 1 computer for every 13 people, compared to roughly 1:1 in the US. Then, you have to actually wonder - just how much money are these users generating? A fairly large chunk of these PCs were bought with totally pirated OS and software. Baidu, China's "answer" to Google is in fact more like China's Pirate Bay - its success is through hosting pirated media! And, even with the lion's share of 384 million users, its turnover was less than $3 billion in 2009, an eighth of Google which has over a billion users.

Sure, the penetration is going to increase, and maybe someday we can expect 1.3 billion computers (or their future equivalents) in use. But for that to happen, we will also have to see dirt poor rural farmers lifted to the equivalent salary of the average American "poor." To match the US now, China "merely" has to maintain wages grow at 10% for the next 25 years or so. To overtake the US, it has to maintain this growth rate for about 50 years. Can it? It's doubtful, heck, downright impossible. If you really want an idea of the growth of the Chinese internet, follow Baidu.

Obama Bowls Us A Six

Hi folks in the blogoverse,

Last December I wrote about the fate of the ISS and what might happen to it, for my IEMBA Seminar at Temple University. I predicted that the ISS might be wiggled an extension, but I certainly wasn't prepared (along with most of the space community) for Obama's doozy of a budget that he dropped on us in February. It was very interesting for me though, as I was just studying an introductory accounting & finance course (yay, I now know what a debenture is!). ISS extension to 2020... great! ISS budget boost, wow, even greater! But nobody was prepared for the outright cancellation of Ares V (not gonna happen), Ares I (lame duck, doomed to be Xmas dinner) and Orion. And now the US was supposed to pay the Russians a whopping $100 million per Soyuz seat. Uh oh. I said the Japanese were not going to trust the Russians, and those guys have learned the art of capitalism. No disrespect to Roskosmos, but wow! $100 million? And, dear readers, NASA is having to rely exclusively on private transport to ISS, which, though good and cheap, is not going to be soon. And last of all, no clue as to NASA's destination, no timetable, just a vague promise to be "somewhere, sometime." Urgh. Administrator Bolden did his best to field the blame like the good soldier he is, but man this is turning out ugly.

Well, the Congressmen are lining up for a fight because they don't want to see all those shuttle layoffs in their districts, nor are the big space companies wanting to give up their juicy contracts. Optimists are predicting a sensible compromise (perhaps with DIRECT - yay!) Pessimists see an even more botched budget and space plan. As for yours truly? I'm somewhat ambivalent. I favour a space shuttle extension to 2015, with two flights a year on a lean budget to service the station properly. A lot of knowledgeable folks who work on or near the shuttle have said that the ISS is not really meant to be run on the meager offerings of Progress, ATV, HTV and the COTS suppliers - SpaceX and Orbital. No offense to those guys but it is a matter of tonneage, and also seats. Shuttle extension also preserves the vital elements for a heavy lift booster - like DIRECT or Ares-V Lite as some call it. SSME, External Tank, Solid Rocket Boosters. This way money is pooled between the two programs, there's a smooth transition and all those skilled workers aren't lost to second-hand car dealerships.

Some 15mm SF I'm Working On

Some 15mm SF that I've been working on. All three models are from Ground Zero Games. On the left is an armed civilian, middle is from their Alien Mercs line and on the right is a Crusty (not-District-9-Prawn). All of them have amazing detail. The green fellow in particular was a pleasure to paint, brown, green skin and rusty weapon. I painted him in Warhammer 40K style as one of their Orks. Maybe I can tempt some of that crowd into discovering that there are actually other games out there! (I wonder if you asked them if they had heard of Napoleonics, what they would say...)


Next up is an APC from Old Crow. I try to keep all my vehicles as non-metal because I'll be moving back to SA from Japan very soon, and the weight of all that lead will soon add up. It can double as an SADF Ratel or any one of the other modern APCS, as well as an SF one. Painted it desert camo, as SA military hardware is usually this drab brown and it's fairly universal as far as modern conflicts go. I also figure habitable exoplanets will usually be dry and desert-y too.

Figures are: the Alien Merc, an Old Crow trooper, GZG NAC Marine, GZG Ravager, GZG Crusty, another GZG NAC Marine. As you can see, the Old Crow guys are very short and skinny compared to everybody else. That's fine, I'll probably make them Chinese or Japanese troops and not mix them in with other figs. One grumble I have with Old Crow is that there's no SAW- or LMG-equipped troopers. GZG figs all have fantastic detail, although the NAC guys look like they've been chomping on the McStarBurgers when held next to the Old Crow. Maybe I'll paint them in nice slimming colours...

Not sure what I'll do with them yet. I have painted up about 20 Crusties and 40 Old Crow so I could do a humans vs. aliens slugfest, but I'd also like to do some post-apocalyptic scenarios, getting friends to role play as themselves with the armed civvies.

The People Demand Free Rocket Engines!

I'm wondering how much it costs to ship 4-odd tonnes of space shuttle engine to South Africa. The reason I say this is because NASA is giving away worn-out space shuttle engines for FREE!!!! plus of course shipping and handling costs. The SSMEs as they're refered to by jargon-loving NASA (and me) are good for several missions before they wear out and need replacement. Brand new, they cost something on the order of $50 million apiece, so that is some serious discounting going on. What I love about these things is the way they look so dirty and scruffy now, just like the space shuttles, having been reused over and over again. Sadly after 2010, we're looking at the end of the Space Shuttle Program. Sniff. A possible 3-flight extension is being looked at up to 2012, to continue servicing the ISS (after NASA seriously screwed up the shuttle replacement).

The New York Times Article

Oh, and the shuttles themselves are up for grabs, although they are a bit more pricey at $30-odd million each. Mark Shuttleworth, care to give me a loan? But, the good news is that the shuttle is not dead. The SSME, the trademark orange external fuel tank and the white solid rocket boosters on the side will live on. Latest rumblings are that NASA's new administrator, Charlie Bolden, will adopt a new launcher design, based closely on the space shuttle hardware. The current (old) design, Ares V and its smaller counterpart Ares I, suck in many ways which I won't bother going into here, but safety is one of them.


This new launcher is based on an old NASA study about making a big heavy lifter using shuttle components. A group of space enthusiasts and engineers inside NASA resurrected and refined the idea, risking getting fired in the process (can you believe that!?) Called Team DIRECT, they've been championing the launcher design for years now. I'm proud to have offered some (incredibly minor) support to their cause. So, instead of outright cancellation when Ares I and V became engineering and budget nightmares, we have the good old space shuttle once again. No wings, but you don't need those out there, in the black...

Visit the team's website...

Shattered Horizon - Which Way Is Up?

I've been playing with a game I got for a steal on Steam - Shattered Horizon (75% off - $5!!!). Basically, it's a First Person Shooter in space. Pretty much like the battle in Moonraker. This especially brings back memories of Descent on my old computer. But what it most of all feels like to me is Ender's Game - the enemy's gate is down (I'll have to explain this bit a little later)!!

A bit of comment on the game. It's set in the 2040s, and a "mining accident" has resulted in a large chunk of the moon being blown off and the debris orbiting the Earth in a deadly ring of boulders. The International Space Agency (ISA) and the Moon Mining Corporation (MMC) are both trapped in orbit, and supplies are hard to get through. The ISA blames the MMC for the "accident" and wants to bring them to book. The MMC of course don't want to go to jail and don't want to suffocate / starve so they wind up raiding supplies sent to the ISA. Pretty straightforward and kind of original plot - not that it really matters, as Shattered Horizon is a multiplayer-only game.

The game is not entirely ruled by the laws of Newton - there are maximum velocities but you do keep drifting once you fire your thrusters. Stopping dead is heard unless you anchor onto something with your boots. Aiming is harder when not anchored, so this is the better option for shooting. It also gives you better cover. Your weapon is a standard assault rifle, with some utility grenades - EMP to short out other players' suits and slow them down temporarily, a concussion warhead to knock other players away and ice clouds to hide behind or in. And a bayonet to slice suits open. Despite the single weapon choice, and the fact that there are only 4 maps availabe (one being a privatised ISS - pretty much like my previous posts' idea!), the game is lots of fun and has a dedicated following. The devs are also responsive to requests and feedback, and can incorporate ideas brought up in forums to updates. They also give clear Yes/No responses as to what they are going to do. For example, some players wanted blood squirts etc. and the devs responded No, because that would alter the game's rating to a more mature rating. Personally I think this is a good idea - plenty enough games have blood and guts already. The only thing really lacking is a solid single player experience, but with bots that may come in time.

The game is produced by Futuremark, those guys who build software to test the speed of your system, and this is a pretty demanding game. You wouldn't think it, but the shaders required to make the rocks look rocky chews up a lot of system power. There are LOTS of objects being rendered as well, unlike games set indoors with few visible objects. My laptop runs an ATI Radeon 4570, a sort of low-middle end card that will handle older DX9 games like Fallout 3 fairly well, but Shattered Horizon is DX10 only and really takes it through the wringer. After turning graphics way down, turning off Windows Aero and installing the latest video drivers, I managed to get the game running smoothly at about 20-25 fps (frames per second), which is the minimum for shooter games if you don't want to get shot every single time (movies typically run at 24 fps).

In terms of realism, this game is both quite realistic and gratifyingly fun. There's only a single multipurpose rifle, as I mentioned, as you don't want to fiddle with other weapons in zero G. "Sounds" in space are handled as being part of a situational awareness suite, which makes sense to me. Make gunfire sound like gunfire, and humans will react accordingly. Get your suit knocked out by EMP or power the suit down for stealth, and the sounds go away. You hear muffled sounds transmitted by anything you are in contact with, but that's it. Really atmospheric.

As for the Ender's game reference, the book basically involved young child cadets fighting with laser tag guns in a zero-G battle room. Ender, the main character of the book, revolutionised thinking by telling his posse to think of the enemy's gate as being down. In other words, to advance feet first because that made you a smaller target and forced you to think in 3 dimensions. The ISS level in Shattered Horizons makes me think of this quite often. I find it refreshingly mind expanding to pop up from a rock, hanging upside down and shoot somebody in the top of the helmet. It's also quite funny to get shot in a completely random direction. Watching other players' creative tactics is quite rewarding, especially when friends work in teams.

Overall, the game is pretty darned original and fun, and considering the price I got it for, is really worth it. Good for just mucking around in between working or hours of red-eye LAN gaming. Also a very good example of how a small company can produce a really quality product and stay in touch with their consumer base. Other games devs should take notice, in amidst this sea of World War II shoot-em-ups and Half-Life 2 wannabees.

Avatar and Lithium

Avatar and Lithium. What the heck does a movie and an element used to treat bipolar disorder have in common? The answer is planets. But first, let's talk about Avatar, a most pleasant surprise for this SF bunny. Yes, this review is kinda late but it's not like a lot of people read this blog anyway.

I had the opportunity to watch it in 3D at IMAX, which was terrific. As it was subtitled, I had Japanese floating in front of me and when the Nav'Ri spoke I had to struggle to read the kanji to figure out what they were saying. Mostly guesswork. I'll have to wait for the DVD.

The arrival sequence at Pandora was most gratifying, because the interstellar transport was actually a well-designed vessel, not something created by a 7-Up gulping graphic designer with no understanding of engineering and far too much Gundam influence.

You can read Winchell Chung's rave review here.

Pandora itself is a fascinating planet, or rather, moon. It orbits a gas giant around Alpha Centauri B, although the interesting thing is that astronomers have watched the Alpha Centauri system and are pretty sure that there are no gas giants in orbit around either. Theory says that there may be some planets tucked in there, and the two stars are far apart that planets in the "Goldilocks" zone won't get ejected by the stars' gravitational tug.

Now here's the interesting part. We know that stars that have planets appear to be depleted in lithium, including, of course, our sun. How lithium depletion relates to all this, we're not sure. th Alpha Centauri A and B have high levels of lithium depletion. There are two interesting possibilities here:

First, about a third of all stars seem to have lithium depletion. So as many as 1 in 3 stars may have planets. Of course, so far this means planets we can detect, not terrestrial-sized planets. Normal (lithium-rich) stars may be swarming with asteroids and terrestrial planets, which we can't we can't yet detect.

Second, Alpha Centauri A and B may well harbour small rocky planets. Maybe quite a few, since they are both heavily depleted compared to our own sun. But that remains to be seen, since there are so many other factors that could influence planet formation. For all we know, the planets may have been ejected into space by tidal forces long ago. It seems likely that a giant planet did not form close in and gobble up all the newly formed planets, because that giant planet would have wound up dumping its lithium back into its parent star as it continued inwards on its death spiral (computer simulations of "hot jupiters" indicate that they are so big that drag from solar wind decays their orbits and dumps them into their star).