Common Sense

(Ed. note: Doc Johnson sent me this the other day after our conversation about the space program. I am the young friend he mentions. I want to state that until I get my moon base and my death ray with which I plan to hold the earth hostage, I am firmly against the space program.)

Why space at all

A young friend asked me why there should be a space program at all, when there is so much to do at home. She wants to be an oceanographer, and thought we should explore the oceans first.

My answer had two parts: (1) parallel vs serial exploration, and (2) the unpredictable benefits of human exploration.

If we explore things one after the other, there is little opportunity to compare and contrast ideas. Because we are human, entrenched theories are hard to overturn later when more data are available.

The unpredictable benefits of human exploration are something we have not seen since the moon landings. The last one was in 1972.

Only our robots have gone exploring since then. But it takes the human touch to uncover those unpredictable benefits.

President Bush’s “Vision for Space Exploration” is the first directive since Kennedy’s to explicitly call for human exploration: going back to the moon, then on to Mars.

All these years in earth orbit with the Shuttle and the Space Station were not wasted, as long as we understand the mistakes we made before, and do not repeat them.

The worst mistake was a NASA too driven by Congressional budget politics. This drove the versatile Shuttle’s design to something inherently dangerous to fly.

My opinions about the new program follow, in good news / bad news format:

Good: CEV will replace Shuttle, scheduled to retire in 2010. Bad: the minimum four year gap between them risks ending manned flight; are we retiring Shuttle too soon ?

Good: the “Apollo-on-steroids” CEV makes best use of existing technologies. Bad: CEV will take twice as long to fly as did Apollo (none of the “old hands” are left, and the organization is no longer small and lean).

Good: CEV will supply the space station. Bad: station science is being abandoned for budget reasons (that old worst mistake again).

Good: CEV goes to the moon and eventually Mars. Bad: more space station science is needed to figure out whether long stays on moon or long trips to Mars are survivable.

Good: we’re going back to the moon. Bad: the best reason to go is not included (the moon is a safe place for nuclear rocket engine¹ development, in turn making cheaper, faster space travel possible).

Good: we’re going on to Mars. Bad: we’re abandoning the space station prematurely to do this “within budget” (that old worst mistake again).

Good: we have a station to which we could add appropriate infrastructure (space tug², fuel dump³, inflatable workshop⁴) to help us go to the moon and Mars, and other useful jobs as well. Bad: there’s no plan to do this.

We are at war, which must take precedence in terms of schedule and money, and pay-as-you-go is the right idea. Yet we went to the moon while embroiled in Vietnam, so I know this is possible.

Let’s not screw this up with that same old worst mistake, or by leaving out the missing pieces.

Footnotes for details not included in the original column submittal:

Nuclear rocket engines – these would include both gaseous-core fission devices, and nuclear explosion drives. Both offer high impulse and high thrust simultaneously, unlike any other now-known concepts. Only those two factors together can offer fast travel.

Space tug – this would be a piloted vehicle kept permanently at the space station, fueled from a supply dump near the space station, and used for a variety of tasks. It might be a version of the CEV, and it might not be, but it needs the capability of moving massive objects from any orbit (including geosynchronous) to the station. It also would be used to retrieve, maneuver, and dock items sent up from earth, so that the expense and risks of automated docking on every single mission can be avoided. These operations support on-orbit assembly of moon and Mars vehicles, and repair and maintenance of satellites.

Fuel dump – any upper stages and fuel tanks currently deorbited should instead be carried all the way to stable orbit. These would be retrieved by the space tug, usually most economically as a part of some other mission, and tied together in a cluster near the station, with vents open to clean residuals by vacuum-boiling. A suitable subset of these could be manifolded together as tankage able to receive fuel shipments sent up from earth. In this way, large fuel supplies could be gradually accumulated from small shipments for missions away from earth, and for the tug itself. For safety’s sake, this fuel dump should not be located at the station, just near enough for a short hop in the tug.

Inflatable workshop – the feasibility of this kind of structure is being demonstrated by the Bigelow orbital hotel project. The attractiveness of this approach is that the deflated, folded-up structure is small enough to use smaller launch vehicles. A workshop designed for addition as a station module would need large size and a large doorway, and would need to hold its installed shape even when depressurized. The tug brings items into and out of this module. With the door sealed, the workshop can be pressurized. While still zero-gee, the environment would be shirtsleeve. Being able to dispense with bulky spacesuits would greatly facilitate on-orbit assembly, repair, and maintenance activities.