Exploratory Engineering:
Applying the predictive power of science
to future technologies

by Eric Drexler on 2009/06/26

While I’m on the subject of foundational concepts in the relationship between science and engineering, here’s the outline of a methodology for applying current science to assess lower bounds on the capabilities of a select subset of future technologies. (As many of you know, some of those lower bounds are startlingly high.)

A subset of the potential capabilities of future levels of technology can be understood by means of a design process that can be described as exploratory engineering. This process resembles the first phase of standard design engineering (termed conceptual engineering, or conceptual design), but it serves a different purpose:

  • In standard engineering, design leads to the manufacturing of a product.
  • In exploratory engineering, design leads to understanding of what a future manufacturing process could produce.

Because of this difference in objective (products vs. knowledge) conceptual engineering and exploratory engineering have both similarities and differences:


Conceptual engineering

Exploratory engineering


Create and evaluate system-level designs (typically parameterized)

 — Same —

Enabling technology

Current fabrication technologies

Prospective fabrication technologies

Process of analysis

Specify a system-level design, describe the necessary subsystems and components, calculate their required performance parameters

 — Same —

Basis of design calculations

Known performance of specific classes of existing materials and components
(Designs may exploit poorly understood phenomena)

Physics-based, lower-bound estimates of the performance of specific classes of potential materials and components
(Designs must exclude poorly understood phenomena)

of design calculations

Estimates of the performance of fully refined, system-level designs

Lower-bound estimates of the performance of fully refined, system-level designs

Production and performance

Product is intended to be manufacturable in the near future and competitive with well-designed products based on the same technologies

Product is not intended to be manufacturable in the near future, and need not be competitive with well-designed products based on the same technologies

Implications for design criteria

Seek to maximize performance and minimize cost of production, while ensuring that the product will be reliable

Seek to minimize the cost of design and analysis, while ensuring that lower-bound estimates of performance will be reliable

Implications for design choices

Seek efficient designs with adequate but not excessive design margins, aiming to produce a good estimate of the expected performance of a detailed, fully optimized version of that design.

Seek simple designs with generous design margins, aiming to produce a reliable estimate of the minimal performance of a detailed, fully optimized version of design of the same general kind.

Results of the design process

A system-level design concept, intended to guide decisions regarding engineering and production

Estimates of the capabilities of the potential products of future fabrication technologies, intended to guide evaluation of research and policy options

In the early 20th century, a missing fabrication technology was the combination of engineering expertise and metalworking techniques (among others) that were required to build large aerospace vehicles. The physics of rocket propulsion, however, were well understood, and the strength and weight of large, well-made aluminum structures could be estimated with reasonable accuracy.

On the basis of exploratory engineering applied to this kind of knowledge, engineers who studied the matter were confident that orbital flight could be achieved by means of multistage chemically fueled rockets. By the 1940s, a study by the British Interplanetary Society had filled in considerable detail and given a good estimate of the size of a vehicle that could reach the Moon.

Those who hadn’t studied the matter were sometimes confident of the opposite.

Astronomers who knew the daunting speed of orbiting objects (but didn’t trouble to examine the exploratory engineering analysis) sometimes called spaceflight absurd. In a characteristic move, a Professor of Physics and Chemistry, one A. W. Bickerton, demonstrated the impossibility of something irrelevant, then generalized it: He did a silly calculation that implicitly assumed that a rocket must put its fuel into orbit (and a bad fuel, at that), then announced that spaceflight was simply impossible.

Reasoning from the unworkability of a bad idea to the impossibility of a well-researched engineering concept is a repeated theme of interactions at the interface between science and engineering. (Engineers ignoring a crucial scientific fact is, of course, another.)

Here’s an entertaining list of quotations from the history and prehistory of flight, and spaceflight.

See also:

{ 2 comments… read them below or add one }

Jeffrey Soreff August 29, 2009 at 5:33 pm UTC

Would you consider “Heteroaromatic Rings of the Future” (William R. Pitt*, David M. Parry†, Benjamin G. Perry‡ and Colin R. Groom, J. Med. Chem., 2009, 52 (9), pp 2952–2963
DOI: 10.1021/jm801513z) to be exploratory engineering? They aren’t specifying the fabrication technology in detail, but do select a large subset of the skeletons as synthetically tractable. In the application to medicinal chemistry, simply increasing the number of viable alternatives is a help, so in
that sense they are improving a lower bound on performance.

Eric Drexler October 31, 2009 at 8:35 pm UTC

Yes, of a sort — but a rather unusual sort.

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