Every now and then you stumble across something that provides tantalizing yet nonchalant hints to something amazing. Recently this occurred while perusing a Boeing report on closed life support systems for spacecraft. One concept mentioned and minimally described was a previous 1981 study of a spacecraft meant to transport crew to the asteroid belt for the purpose of mining asteroids for their resources. Just the basic concept was fairly amazing on its own, especially all the way back in 1981. Second: the propulsion system was vaguely described as a nuclear fusion system. Third: well, here’s the disappointingly small diagram that was included for illustration purposes. See if you can see what makes the design especially interesting…
What can be seen: three arms that rotate for artificial gravity; three vast radiator fins and a relatively tiny fusion engine in the tail. But what makes the design amazing: just in front of the spacecraft is a Space Shuttle Orbiter, giving a sense of scale to the vehicle. It’s *vast.* And it would have to be… the cargo transported to the asteroid was 150 metric tons. Plus the passengers, all 1,250 of them. All ONE THOUSAND TWO HUNDRED AND FIFTY of them.
The vehicle massed 10,000 tons; the powerplant (two 6 GW fusion reactors, spitting out 4.8 GW of thrust power, 2.8 GW of heat needing radiating and 4.4 GW of high energy neutron) massed 2000 tons; 4000 tons of hydrogen fuel; and 4000 tons of spacecraft/payload/passengers. The vehicle would boost for 11 days, coast for 226 days and brake for 13 days to rendezvous.
That, sadly, is all that’s available in the report I have. A FOIA request has been made for the reference that *seems* like might describe this further.
I hope to be able to define this vehicle further. As it is I can only guesstimate sizes; the habitation modules at the ends of the arms appear to be repurposed Shuttle External Tanks. But even nine of them would seem to be kinda cramped for 1250 people for two-thirds of a year… nearly 140 passengers per tank.
What a sexy ship!
If it was using deuterium-deuterium fusion with an exhaust velocity of 4.2c, my slide rule says the ship would have a delta V of around 100 km/s. Which is quite impressive, actually.
The heat radiators are triangular in order to keep them inside the shadow cast by the anti-radiation shadow shield on top of the engine. Otherwise the bits extending into the radiation zone would be prone to neutron activation, neutron embrittlement, and scattering deadly radiation onto the habitat modules.
The centrifugal gravity arms are quite long, but you need that to reduce the required RPMs to a low enough value. Above 3 RPMs or so some crew would be subject to spin nausea.
“…all the way back in 1981.”
As far as I know, the earliest reference to the idea of asteroid mining occurred in 1898 in ‘Edison’s Conquest of Mars’ by Garrett P. Serviss:
“I shall never forget the sight, nor the exclamations of wonder that broke forth from all of us standing around, when the yellow gleam of the precious metal appeared under the “star dust.” Collected in huge masses it reflected the light of the sun from its hiding place.
“Evidently the planet was not a solid ball of gold, formed like a bullet run in a mould, but was composed of nuggets of various sizes, which had come together here under the influence of their mutual gravitation, and formed a little metallic planet.
“Judging by the test of weight which we had already tried, and which had led to the discovery of the gold, the composition of the asteroid must be the same to its very centre.”
An exhaust velocity of 4.2c, Win? Seems a bit extreme.
Remember, this design was from 1981. The high value of 4.2c is a result of compound interest and inflation.
Probably.
4.2 c is the theoretical maximum for D-D fusion, when the exhaust is strictly composed of fusion reaction products.
This means if you are using fusion to heat hydrogen reaction mass the exhaust velocity will be orders of magnitude less.
And if you are using fusion reaction products, you will get that exhaust velocity, but the propellant mass flow will be so microscopic that the thrust will be measured in singled-digit Newtons.
…the data for which I probably obtained from reading one of Dr. Crowl’s blog posts.
> 4.2 c is the theoretical maximum for D-D fusion
Can’t say as I agree with your detective work there Lou. I’d suggest that it’d be more like 0.042 c, rather than more than four times the speed of light.
(Homer Simpson) “D’OH!!” smacks forehead
You are absolutely correct.
I’m a fumble-fingered typo-maker who needs new glasses. You can just ignore anything I post.
I meant to type 4.2% c
If the jet-power is 4.8 GW and the mass-ratio is 5/3 for a return to Earth mission, then an exhaust velocity of ~100 km/s and a total delta-vee of 51 km/s. That means a mass-flow rate of 0.96 kg/s.
BTW the CELSS paper which references the BIG asteroid crew transport is available here: Controlled ecological life support system
Interesting paper. It covers the use of CELSS in several different scenarios, the Ceres base mission being the most futuristic. The asteroid transport is assumed to be part of a quite elaborate transportation network in 2050 i.e. ~70 years ‘from now’ (c.1980). The ‘shuttle’ in the illustration is the orbiter part of a two-stage HLLV capable of orbiting ~490 klbs a throw. The first stage of the HLLV is a beefy flying fuel tank, using 13 CH4+LOX engines for lift-off. There’s 8 SSMEs on the orbiter. Thus the habitats on the arms of the transport aren’t repurposed STS ETs – and can be whatever size they need to be. LEO to GEO transport is via an SEP freighter with a 500 klb payload. The fusion transport leaves from GEO. The assumed crew at Ceres is 5,000 persons. The paper also mentions an assumed transport cost to Ceres of $462/kg (1982$ presumably.)
> The ‘shuttle’ in the illustration is the orbiter part of a two-stage HLLV
Maybe. Unless you see something that says explicitly that, the “shuttle” is drawn too small to be sure just what it is.
And this one is Reference 91 of the CELSS study, detailing the LEO/GEO access architecture: Technology Requirements for Future Earth-to-Geosynchronous Orbit Transportation Systems
I did some pointless 3D sketching with the tiny smudged drawing from the report, I figure the spacecraft is about 500 meters long, give or take an order of magnitude.
http://nyrathwiz.deviantart.com/art/AsteroidMiningCrewTransport-526559658
Hey Scott, have you heard any more about the paper? I’ve scoured the Net, with no luck. I did think to ask Dana Andrews if he still had a copy, but papers from the early 80s tend to end up “archived” into inaccessibility. I’ve asked Alan Bond and Greg Matloff for old papers in the past, with the same outcome. A filing black-hole tends to eat anything over 20 years old…
Sadly nothing useful to add. I managed to get hold of the reports referenced in the original… and they had nothing to say about this ship or the larger mission. Either this stuff was taken from a report that *wasn’t* called out in the references, or it came from something unpublished. Neither would surprise me. Reports would often be slapped together using bits from fifty other reports, but only twenty of ’em would get referenced. The other thirty would just seem redundant, or sometimes the authors might not even know what they were (because the copy the author had was incomplete, missing the title page… the authors would want to use the data anyway, but since they couldn’t actually say where it came from, they just glossed over that bit).
The annoying thing about that fusion engine image is that it looks elusively familiar, but I can’t remember the other paper I saw it in. So you managed to get a hold of the Boeing report edited by Dana Andrews?