The Space Reviewin association with SpaceNews

ISDC 2024

While far too large to be considered a smallsat, the development of Bigelow Aerospace’s Genesis modules benefited from the same design philosophy used for microsats. (credit: Bigelow Aerospace)

Microspace and human spaceflight

Spaceflight has many different communities. Whereas human space activities, both public and private, are often mired in bureaucratic or financial uncertainty—and whereas the global comsat industry continues to function cyclically but smoothly —in a growing corner of the space industry there is a vibrant community doing very exciting work indeed. That industry is the small spacecraft industry; and at the annual AIAA/Utah State University Conference on Small Satellites this week, the achievements and potential of “smallsats”, as well as the design practices underlying their development, will be the topics of discussion.

The smallsat industry—widely driven by what many refer to as the microspace philosophy—represents a fundamentally different way of approaching space missions, and a different way of doing business as a result. The microspace philosophy is predicated on embracing commercial-off-the-shelf (COTS) technologies; aggressive and early prototyping and testing; rapid development schedules; and focused objectives and lean engineering teams. This approach yields fast, inexpensive missions that track modern technology curves much more closely than conventional space programs.

Yet in spite of its successes, microspace has had relatively little overlap with conventional space. And of particular interest to the author, the benefits of microspace have not widely migrated to the arena of human spaceflight. But it may be that the philosophies of small spacecraft development, as well as small spacecraft themselves, can offer important benefits to present and future human activities in space.

A brief overview

Small satellites themselves are of course by no means “new”. Indeed, Sputnik 1—the first artificial satellite—was an 84-kilogram spacecraft that would today qualify as a microsatellite 1. The first communications satellite, SCORE, was a 70-kilogram satellite built in 1958; the first satellite to transmit a television signal across the Atlantic Ocean in 1962, TELSTAR, was a 77-kilogram spacecraft 2.

The smallsat industry—widely driven by what many refer to as the microspace philosophy—represents a fundamentally different way of approaching space missions, and a different way of doing business as a result.

However, it soon became the case that satellites (in particular, communications and remote sensing missions) tended to increase in size to match increasing launch vehicle performance, in order to maximize spacecraft performance versus total system costs 1. With more capable launch vehicles, the high cost of spacecraft, and an increasing reliance on space assets, the aerospace industry tended to develop even more massive and more capable spacecraft in turn. While some organizations (such as AMSAT) forecasted the upward cost spiral that this approach could lead to, the space industry at large did not.

One of the biggest issues in spaceflight is that the rate of development operates on too slow a timescale to track advances in terrestrial technologies. The development of new space projects has been limited by the high investment required for space activities (due in no small part to high launch costs) and by the difficulty of mobilizing such investments. A further burden on space missions is that high costs create a natural reluctance to take risks with technology innovation. As a result, many spacecraft are based on older, “S-Grade” or heritage parts, which are generally expensive, have long lead times, and which have long since been surpassed by terrestrial equivalents. Space programs, therefore, take a schedule hit while procuring their obsolete subsystems—and they get heavier, too.

It has been observed that such mechanisms can lead to a high-cost, positive feedback spiral 3. Initially, if a space program is perceived to have high cost, two things can happen: first, in order to get sufficient funding for the project, many promises must be made to entice and secure stakeholders. Promises made to investors translate to added mission objectives and requirements, which can severely and unnecessarily constrain the program at its earliest stages. The spacecraft becomes “feature-creeped”, and gets more expensive and harder to develop as a result. Second, stakeholders must be assured that there is a high probability that all bloated program objectives can be met, leading to the incorporation of widespread redundancy (which often buys little reliability but much complexity), while simultaneously decreasing the level of acceptable risk. The approach becomes one of risk aversion instead of managed risk, and conservatism pervades the entire design process. Heritage parts are chosen, margins are over-specified, and complexity increases, leading to customer- and management-driven desires for more documentation and design reviews to verify that the whole thing will actually work. And on it goes. This may sound familiar to many throughout the space industry.

What is microspace?

The microspace approach differs markedly from conventional spacecraft development. Microspace fundamentally involves the design of space missions, satellites, and engineering teams that emphasize rapid, incremental advances in technology at relatively low cost. It follows that a key way of achieving such objectives is through the use of multiple, independently launched spacecraft, each using the latest available technology to simplify design and maximize utility, and each of which demonstrates the next incremental improvement in technology 3.

The impact of this approach is significant: first, emphasis on the use of modern COTS technology drives a reduction in spacecraft size at a given level of functionality. New technologies developed in terrestrial markets can be rapidly integrated into spacecraft, reducing cost and increasing capability further. Whereas conventional spacecraft use S-grade parts with lengthy procurement processes, smallsats are often designed using commercially-available, highly integrated components that both closely track terrestrial technology curves and which can often be delivered overnight. And whereas S-grade parts may be so costly as to mitigate extensive testing, COTS components used in smaller spacecraft are often extremely cheap, thereby allowing engineers to compensate for their lack of space heritage by engaging in much more rigorous testing at a much earlier stage in program development 3.

The microspace philosophy is predicated on the notion that faster and cheaper missions result in more accomplishments in space, which drives both confidence and demand for space missions as well as their level of technological advance.

Another major benefit of the microspace approach is that spacecraft engineers gain experience in actually flying real spacecraft. They get to do it often, and learn to embrace new technologies. A small satellite engineer may see his or her work reach space annually, as opposed to every decade, if ever. Tight schedules drive innovation, and the lean nature of smallsat teams allows engineers to solve problems cooperatively, quickly, and with a minimum of red tape. Many engineers quickly gain a system-level (i.e. big-picture) perspective, and the conventional requirements-driven approach to spacecraft development becomes tempered by capabilities-driven, “bottom-up” thinking. Simplicity and carefully considered requirements are strongly emphasized, and feature-creep is avoided with what has been referred to as “ruthless minimalism”. Standard analyses used in larger programs can often be truncated or avoided entirely with careful thinking upfront. Many small spacecraft are subjected to no further failure analyses than a so-called “death modes” analysis, performed to ensure that under no circumstances can the spacecraft find a way to kill itself or fail to complete its mission, while still accepting the reality of inevitable failures. Good design is emphasized over un-needed, un-thinking redundancy, and risk-taking is accepted and managed.

In summary: the microspace philosophy is predicated on the notion that faster and cheaper missions result in more accomplishments in space, which drives both confidence and demand for space missions as well as their level of technological advance. As more missions are flown, more COTS technologies gain space heritage; more ambitious missions are enabled; and more engineers gain experience in aggressive development programs. The small spacecraft community builds fast, tests aggressively, and focuses on consistent improvements in technology. And thus, it is of interest to some that the benefits of this approach be transferred, if possible, to larger programs.

Making microspace bigger

The direct benefits and potential of small spacecraft—that is to say, the missions they can actually accomplish—have been widely discussed. Wertz previously reviewed several of the benefits of small spacecraft (with the emphasis on operationally responsive space, ORS), which included:

  • Surveillance and Reconnaissance;
  • Communications;
  • Weather; and
  • Space Situational Awareness

(See “It’s time to get our ORS in gear”, The Space Review, January 7, 2008) To this list I’ll add applications in my experience, such as ship traffic monitoring; astronomy; space environment experiments; remote sensing; store-and-forward messaging; technology demonstrations; and potential planetary exploration missions. Ambitious technology demonstrators, such as solar sail missions and experimental de-orbiting techniques, represent some of the exciting near-term missions that can be accomplished at the nanosatellite scale. Much like private space activities, there doesn’t yet seem to be a single “killer app” for small satellites—instead, there are a large number of good ideas that combine to keep smallsat endeavors healthy.

Yet while applications for small spacecraft currently abound, neither the microspace philosophy, nor direct contributions of small spacecraft, have migrated in any appreciable way to human space activities. There have been some notable crossovers, however, which by themselves suggest ways in which microspace might contribute to larger activities.

Indirect contributions

Perhaps the most noteworthy example of microspace crossover into the human spaceflight world (at least to NewSpace supporters such as myself) was in the development of the Bigelow space hotel prototypes Genesis 1 and Genesis 2, which “likely represented the lowest-cost mission of its kind in the history of aerospace, including spacecraft fabrication and the launch itself”. The avionics of Genesis 1 and Genesis 2 were largely developed by teams with little-to-no experience in human spaceflight, but who brought considerable microsatellite and nanosatellite expertise to bear on the project. With a lean and focused development effort characteristic of microspace programs, Genesis 1 went “from paper to orbit in 15 months”, using largely COTS components in its development. In an industry where every kilogram adds enormous expense, microspace-style development using modern systems can offer significant cost savings, allowing large fractions of spacecraft functionality to be pushed into software on embedded systems. The general willingness to look outside the realm of traditional aerospace suppliers for components, and to accept already-available commercial solutions rather than insisting on re-inventing proven terrestrial systems, are among the core competencies of the smallsat community. In addition, operations simplicity—in which missions are run from distributed commercial laptops and smartphones instead of large custom infrastructure—can also considerably reduce cost and complexity and increase reliability.

In addition to the transfer of expertise, experience and design philosophy, small spacecraft can also benefit human spaceflight directly.

The Genesis 1 and 2 development program demonstrated an important contribution that smallsat expertise can make to emerging NewSpace efforts, which usually don’t have the fiscal resources to do things conventionally. The experience and confidence brought to bear by engineers with multiple advanced missions under their belts can have significant benefits as well. I’ve had the privilege of working with engineers involved in the Genesis program, and consider them to be amongst the finest I know. It is also my understanding that many individuals at companies such as SpaceX—which is ostensibly leading the way in revolutionizing space launch—have extensive backgrounds in smallsat development.

NASA has been using smallsats like GeneSat-1 (above) for scientific work that could provide key data needed for human spaceflight. (credit: NASA/ARC)

Direct contributions

In addition to the transfer of expertise, experience and design philosophy, small spacecraft can also benefit human spaceflight directly. A noteworthy example is NASA’s GeneSat-1. GeneSat-1 was a collaborative effort between Ames Research Center (ARC), industry, and academia to study biological effects of the space environment, notably including radiation and reduced gravity, and is an excellent example of the sort of low-cost research contributions that can be made to human space efforts at the nanosatellite scale. (Indeed, it appears that ARC is at the forefront of this effort at NASA, with an ambitious series of nanosatellite and microsatellites on the horizon.) As well, small spacecraft can serve as rapidly developed pathfinders for human space activities. A notable example from the past (with many not-so-microspace-style follow-ons) was Clementine, a lunar mapping mission. Smaller planetary remote sensing missions have been proposed as well, which can serve as important precursors to human exploration, as well as extremely useful science missions in their own right.

Technology demonstration missions—a cornerstone of smallsats for some time—represent an important contribution that can be made to human spaceflight efforts. In addition to validating new COTS solutions for use in space, small spacecraft can also play an important role in quickly placing experimental hardware in orbit, where representative testing on the ground fails to adequately substitute for operational experience. On-orbit testing of technologies such as new solar cells—which may or may not exhibit radiation degradation in the space environment—represents a useful example. For prospective crewed spacecraft intending to utilize artificial gravity, zero-g rotational dynamics experiments using tethered small spacecraft can offer an inexpensive means of demonstrating relatively complex attitude control. Using small satellites for inspection of larger spacecraft, and perhaps even for repair, is also an exciting application that has generated a great deal of interest. Several missions to demonstrate different autonomous formation flight techniques, necessary to accomplish such goals, are currently being planned at the nanosatellite and microsatellite scale. As well, small satellite demonstrators may be of particular utility in testing systems involving fluids, which behave substantially different in zero-g than in a 1-g environment. This may prove extremely useful for early testing of environmental control and life support systems, or in demonstrating zero-g propellant transfer technologies, which are critical for enabling on-orbit propellant depots.

Two different worlds

In spite of the examples from the previous section, little overlap between the small spacecraft and human spaceflight communities has been experienced to date. By and large, people working in these two areas are different groups with (often fundamentally) different objectives. Yet some of us who migrated to the smallsat world are first-and-foremost passionate about human space development; it’s just that--instead of endless paper studies and unchanging PowerPoint slides--we opted to build real spacecraft with real customers, on schedules measured in months and years instead of decades or, well, never. As a colleague of mine, Henry Spencer, once remarked: “study it forever and you’ll still wonder; fly it once and you’ll know.” Microspace gives engineers the rare chance to put hardware in space, which is difficult to turn away from.

As Henry Spencer, once remarked: “study it forever and you’ll still wonder; fly it once and you’ll know.”

Being able to build and test quickly, fly often, track the technology curve closely and keep missions focused and lean seems like it should have extensibility to human spaceflight. In principle, many different technologies and concepts can be tested in situ by many different smallsat developers, and so it would seem natural that these would permeate to larger space programs directly or indirectly. But this doesn’t seem to happen very often in practice (yet). Unfortunately, it may be the case that the large scatter of small spacecraft efforts worldwide—though beneficial to the industry itself—results in a great deal of duplication and overlap, with little explicit effort or view to migrating the technologies and techniques to larger efforts. Many of my colleagues, though passionate about the matter, confess to having given up on their early goals of contributing to human spaceflight, and have instead turned towards the (quite compelling) engineering challenges of smallsats.

Presently, perhaps the best place for crossover is in NewSpace, where there is both openness to adopting new paradigms and the financial pressure to ensure it. The fundamentally lean and focused microspace approach may be a key enabler of private space activities in the near-term, as it seems to have been for Genesis 1 and 2. As well, the smallsat world may also provide a useful market and stepping stone for emerging launch capabilities aimed eventually at human spaceflight, from Falcon-1 to the recently proposed two-stage WhiteKnightTwo smallsat launcher. And technology demonstrations using smallsats—as well as eventual operational capabilities—should be able to augment human activities in space, serving as testbeds for new technologies.

Time will tell, and hopefully—with increasing amounts of success and an ever-increasing number of missions—there will be more opportunities to transfer the accomplishments of small space to the future of big space.


The author would like to acknowledge Daniel Faber, Luke Stras, Doug Sinclair, Kieran Carroll and Andre Beltempo for their thoughts and contributions to this article. The end result, however, might not reflect their opinions on the matter.


  1. Kennedy, S. O., and Young, Q., “The Rise and Fall of the Capital Asset - An Investigation into the Aerospace Industry Dynamics and Emerging Small Satellite Missions”, SSC06-I-5, August 2006.
  2. Swartwout, M., “Twenty (plus) Years of University-Class Spacecraft: A Review of What Was, An Understanding of What Is, And a Look at What Should Be Next”, SSC06-I-3, August 2006.
  3. Stibrany, P., and Carroll, K., “The Microsat Way in Canada”, 11th CASI Canadian Astronautics Conference, Ottwa, ON. Canada, November 2000.
  4. Fleeter, R., The Logic of Microspace, El Segundo, CA: Microcosm Press, 2000.