AAWSAP DIRD, Space Access: Where We’ve Been and Where We Could Go, March 2010

This Defense Intelligence Reference Document, dated 8 March 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications Program. It is one of a series of advanced technology reports. It surveys the history of space access concepts, covering hypersonic gliders, air-breathing and rocket propulsion, materials, launch options and operating costs. The report argues that reliable, schedulable access to low Earth orbit is mainly a hardware and organizational problem rather than a technology problem.

From the source:Release of 2026-09-18 Incident: 3/8/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD is a historical and conceptual survey of space access systems, contending that the main barrier to routine access to space is a failure to build durable, reliable, operational hardware and the supporting infrastructure needed for regular service to and from low Earth orbit. The report reviews earlier launch and aerospace concepts, especially reusable and aircraft-like approaches, and suggests that U.S. space access development became too strongly centered on expendable rockets derived from ballistic missiles rather than bespoke systems designed for repeated space access and payload delivery. Its central claim is that meaningful future progress will depend on creating a purpose-built space transportation infrastructure, including frequent round-trip capability and orbital support networks, rather than continuing to rely on one-off launch vehicles. Overall, the document presents a forceful case for infrastructure-first space development, though its characterization of past technological choices is more assertive than a fully neutral account of past U.S. space programming.

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cases, the low-pressure hydrogen exiting the expansion turbines is entered into the
rocket motor at a matching pressure.
LACE Deeply Cooled
--• LOX
Figure 29. Two Rocket Air-Breathing Rocket Cycles to Mach S.S. To the lelt is one employing liquefied air
(LACE cycle) . To the right is one employing high-pressure air cooled to near saturation.
There is always the option of direct
ascent by rocket into a trajectory.
Whether by turbojet or rocket, a million
pounds of thrust is always noisy and
smoke filled . We can thank the Russian
design bureaus for arriving at a concept
that eliminated the noisy, smoky, and
hazardous launches by increasing the
operational flexibility of the British
HOTOL concept . Figure 30 shows the
development of the all-rocket HOTOL
system from the original HOTOL. 23 The
original air-breathing rocket HOTOL,
powered by the Rolls Royce 545 engine
as developed by Alan Bond, essentially
used all hydrogen fuel (except for space
operations). The hydrogen required a
volume about 5 times greater than a 6: 1
LOX/hydrogen propellant for a rocket
engine. The classical aerodynamicist's
approach was to minimize drag and
maximize the L/D ratio. But accelerating
to orbital speed requires a low angle of
attack and minimum drag coefficient at
!ln1 ~h Aemsp,1cc flOTOI
Roll s Roya! 545
lruerun Ba E I IOTOL.
RD0l20
~ gt%'.\ =.b
~ RU5Sumll0TOL
RU 0120
Figure 30. HOTOL Evolution: From Aerodynamic
Optimum Configuration to Practical Launcher
Configuration. The latter was developed through British
Aerospace-Russian cooperation .
zero lift (Coo), not maximum L/D ratio. The simple problem, recognized by Kuchemann,
was that the vehicle was too slender and therefore had a large wetted area compared
with its reference planform area; hence, zero lift drag and structural weight were too
high. Even when the BAE Systems team switched to an all-rocket and compromised
the slenderness, this did not significantly reduce the wetted area. The Russian
approach was to design a stout vehicle with a much lower ratio of wetter area to
reference planform area. 24 The trapezoidal cross section of the FOL- 7/Model 176 yields
a ratio of wetted area to planform area less than the circular cross section of the
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27