Ponder this. What exactly do we need for an all-purpose spacecraft to ferry crew and supplies back and forth to low-Earth orbit and the ISS?

From the Encyclopedia Astronautica, see link to the right and look up "Apollo CSM":

Spacecraft Module: Apollo CM. Other Designations: Command Module. Class: Manned. Type: Spacecraft Module.

Crew Size: 3. Length: 3.47 m. Basic Diameter: 3.90 m. Maximum Diameter: 3.90 m. Habitable Volume: 6.17 m3. Mass: 5,806 kg. Structure Mass: 1,567 kg. Heat Shield Mass: 848 kg. Reaction Control System: 400 kg. Recovery Equipment: 245 kg. Navigation Equipment: 505 kg. Telemetry Equipment: 200 kg. Electrical Equipment: 700 kg. Communications Systems: 100 kg. Crew Seats and Provisions: 550 kg. Crew mass: 216 kg. Miscellaneous Contingency: 200 kg. Environmental Control System: 200 kg. RCS Coarse No x Thrust: 12 x42kgf. RCS Propellants: N2O4/UDMH. RCS Isp: 290 sec. RCS Impulse: 26,178.00 kgf-sec. Main Engine Propellants: n/a. Main Engine Propellants: 75 kg. L/D Hypersonic: .3. Electrical System: Batteries. Electric System: 20.0 kWh. Battery: 1,000.0 Ah

Spacecraft Module: Apollo SM. Other Designations: Service Module. Class: Manned. Type: Spacecraft Module.

Length: 7.56 m. Basic Diameter: 3.90 m. Maximum Diameter: 3.90 m. Mass: 24,523 kg. Structure Mass: 1,910 kg. Electrical Equipment: 1,200 kg. RCS Coarse No x Thrust: 16 x45kgf. RCS Propellants: N2O4/UDMH. RCS Isp: 290 sec. RCS Impulse: 358,682.12 kgf-sec. Main Engine: 3,000 kg. Main Engine Thrust: 9,979 kgf. Main Engine Propellants: N2O4/UDMH. Main Engine Propellants: 18,413 kg. Main Engine Isp: 314 sec. Spacecraft delta v: 2,804 m/s. Electrical System: Fuel Cells. Electric System: 6.30 average kW. Electric System: 670.0 kWh.


These are the specifications for the Apollo Command Module and the service module, respectively. The Command Modules were the gumdrop-shaped capsules, the service modules were the extensions on the back end with the engines, directional control thrusters, equipment, etc., that the astronauts needed to get to the Moon.

Okay, leave the CM exactly as written. Mass would then be 5,806 kg for the CM, although given these specifications are from the 1960's technology it will probably be considerably less since we have better and lighter materials, smaller computers and electronics, etc.

The SM -- We're only going up to the ISS at most, so let us rearrange matters. You are not going to need the engine, it's for the translunar injection manuever to put the CSM on course for the Moon. Take out the main engine and its propellant. That's 21,413 kg of mass you've removed. (Leave the directionals, you're going to need those.) You've just given yourself that much mass and space in which to put cargo or people. In fact you don't even have to use all that mass/space. Also, again, these are 1960's numbers. With 21st century materials and electronics, you're talking smaller mass numbers.

Just a random fact thrown in here -- Discovery just took up 15 tons of cargo for the ISS (figure from a news report on Yahoo today). They'll also be returning with 13 tons of ISS garbage, making Cmdr. Collins and crew the highest paid sanitation workers on the planet with the snazziest garbage truck this side of the Oort cloud. But I digress.

Now then. For this next part, see the Boeing Delta launch vehicle site to see the info. Look under the Delta IV category, the Product Cards ~ Technical Summary .pdf file.

Boeing's Delta IV Medium Plus (main booster core, 4 strap-on graphite-exoxy motors) will carry almost 13,000 kg into the proper orbit to get to the ISS. Payload fairing is 5 meters diameter and 14.3 meters length. As you see above, the CM and SM are 3.9 meters diameter, so no problems there. The CM will fit nicely, and with some redesign the SM could be configured for just about anything. Given the lighter materials and electronics and modular design, you could have an SM that could carry cargo, people, science packages, anything. Build them with airlocks on both ends that could fit on the ISS and to each other, and you could have small station modules. We built Skylab that way.

And the Delta IV Medium is not the biggest booster they have. The Delta IV Heavy will carry almost 22,000 kg to ISS orbit.

They're completely expendable (though I don't see why you couldn't replace the Heavy's two extra boosters with the Shuttle's SRBs if you really wanted to see how hard the mule could kick). The Apollo Block 2 command modules went to the Moon and back 8 times. They built and ferried to Skylab. They're a proven, robust technology. Their heat-shields are considerably less prone to getting dinged up (got any Corningware casserole dishes? That's what they're made of). The Russians have been doing things like this all along, and the Soyuz has a better than 99% success rate.

We could do this. We've got all the parts, and what we don't have we could design and build in relatively short order. Compared to the Shuttles the Apollo era stuff is simple. We've got the boosters, Boeing builds those, all we need to do is build the CMs and SMs. We don't need any big new facilities. We could build it all at Marshall. They build the ISS modules there, and these would be smaller and probably very similar to build.

Why aren't we doing this?

I just don't get it.