- Status Report
- Jan 27, 2023
Statement of Mitchell Burnside Clapp before the House Science Committee, Space and Aeronautics Subcommittee
The X-37 is a program that stands a decent chance of providing a significant benefit to future space systems. Although it is frequently advocated as a test bed
for advanced technologies, this is not its principal utility. In my view, the critical need we face is a lack of experience in operating reusable systems that travel in
space, to space, and through space. There is no particular technology the lack of which makes a capability for routine in space operations unrealistic. Rather, it is
the lack of a platform that can be used to develop operational experience that unnecessarily restricts the development of capabilities in this area. X-37 is exactly
that kind of operational testbed.
Some examples from the recent past are instructive. Consider in 1993 the example of the DC-X. By any reasonable standard the performance of the vehicle
was totally unimpressive. Earlier in the year during which I was trained to fly the DC-X from a trailer three miles away, I flew a DeHavilland Tiger Moth,
designed during the 1920s, and I went higher, farther, faster, and on less gas. Performance, however, wasn’t the point. DC-X was the first rocket powered vehicle
that was designed with operations in mind. Unlike the ten thousand or so people necessary to operate the shuttle or the several hundred needed for an expendable
launch vehicle, the DC-X only took about two dozen. The higher performance of the shuttle certainly requires a few more people to look after some of the
systems, but it’s hard to believe that the additional 9,988 souls are all necessary.
Farther back, the aircraft carrier is a good example of the critical importance of operational practice on actual utility as opposed to technological sophistication.
Nothing on an aircraft carrier is especially sophisticated technologically, except some of the landing systems such as ACLS. The steam catapult is technology that
the Victorians would have understood perfectly. The thing that makes an aircraft carrier a combat effective weapon is not the technology of the aircraft or the ship,
but the years of operational procedure and experience, developed beginning after World War I. Every person on a carrier deck knows where to stand, what color
shirt to wear, whom to listen to, which hand to pick up what tool Ð everything to keep each aircraft coming off that deck every one hour and 45 minutes.
We don’t have anything like that in space systems yet. Indeed, what we have instead is systems that are sold as Òtechnology testbeds” without a clear cut
rationale for which technologies are applied to which systems. Newer technologies can be powerfully enhancing, but without operational experience to inform
which technologies are most critical to enhance utility, we’re going about the problem far less systematically than we could be.
X-37 has been described, and I’m quoting from Marshall Space Flight Center’s fact sheet here, as Òa reusable launch vehicle,” and a testbed for advanced launch
vehicle technologies. It isn’t. X-37 is the first serious attempt at a reusable satellite and needs to be understood and appreciated in that sense.
Currently, satellites are just as expendable as launch vehicles, and they cost far more than launch vehicles on a per-pound basis. For commercial satellite
operations, even a very technologically mature GEO communications satellite still consumes about fifty percent of the total program costs. For LEO
communications satellites in constellations, the costs are far higher. As an aside Ð this is in my view the principal reason that the LEO comsat programs of a few
years ago didn’t spur development of a large number of new launch vehicles. The proportion of total program cost consumed by satellite launch is about 15% for a
LEO comsat program. The maximum credible savings a company like Pioneer Rocketplane could offer is less than the uncertainty in the other cost elements.
So X-37 is an attempt at a reusable satellite. It permits the designer of the cargo to concentrate on the optics, sensors, or details of what a satellite designer
calls the payload, not what the launch vehicle provider calls the payload, and leaves the provision of electrical power, cooling, a pointing system, and so on to the
X-37. The cargo carried by the X-37 is unimpressive Ð possibly twelve hundred pounds, but this is twelve hundred pounds exclusive of the support systems,
which the X-37 provides. It’s equivalent to a free flying satellite of perhaps 5,000 pounds total mass. And because that twelve hundred pounds can be recovered,
changed, upgraded, and so forth, there is an opportunity to demonstrate a great degree of flexibility.
DARPA and other agencies now are working on programs to be able to make satellites modular and reconfigure them after they are in orbit. X-37 offers the
possibility of being able to do that on the ground, where labor is more affordable and problems can be worked out more easily
The idea of a space architecture based on reusable satellites, which can be stored on the ground, deployed on demand, upgraded with cargos that are specific to
the mission needs, and so on, offers not only enormous savings in cost, but also the provision of entirely new capabilities that don’t exist today. A military
analogy is mooring an aircraft carrier off the shores of a potential adversary rather than deploying the carrier when the need arises. If the ship is off shore all the
time, the opponent will react, but if the situation is more uncertain, the opponent’s planning is much more complicated.
Even if reusable launch vehicles take another twenty years to become a reality, the X-37 can allow a near term demonstration of an architecture that applies to
them. Already, war games and military modeling and simulation exercises have attempted to incorporate systems like X-37. But we can’t really incorporate the
modeling and simulation results into planning until there is a baseline of experience with reusable satellite systems that can provide a real world input and
correction to those results, any more than a cavalry troop can apply the Gatling gun or a battleship navy can apply the aircraft carrier effectively.
The discussion of which technologies are to be demonstrated in the X-37, like thermal protection or automatic landing, are really not that relevant to the
discussion of why such a system needs to be explored. The problem is not that we don’t have any particular magic bullet technology, but that we don’t have
designs that apply and integrate the technology we do have. It’s not the shoes, it’s the choreography. I’m sure we’ll learn many valuable things about maintaining
thermal protection systems from the X-37 but we could do that on the Space Shuttle, too. I’m equally sure that we’ll learn things from the cargoes carried by the
X-37 that will be of military, commercial, and civil utility and may even help out in a crisis the way that the still-developmental JSTARS system did during Desert
Storm. The idea of a real world system like the X-37 isn’t that it gives you the opportunity to test, but that it gives you the opportunity to debug. And that’s
why it’s a program worth supporting.