Conclusions and Future Program Recommendations
EVOLUTION FROM A NOVEL EDUCATIONAL TOOL TO A STANDARDIZED COMMERCIAL PLATFORM
Previous chapters have described the evolution of CubeSats as an educational, technology development, and science platform. The case has been made that CubeSats share many characteristics of disruptive innovations, and consistent with that, the CubeSat platform is undergoing rapid development toward growing performance and potential for enhanced science impact. Although CubeSats were introduced as a teaching tool, their evolution as a technology and science platform has been rapid and caused, in part, by a fast “fly-learn-refly” process enabled by comparatively low development cost and timely availability of affordable launch opportunities. Fueled by the excitement of access to space, a newfound pioneering spirit, and sometimes even overenthusiastic optimism of first adopters in academia, industry, and the government, the progress of CubeSats toward becoming a science platform has been rapid. Since 2010, the use of CubeSats for science has grown exponentially. More than 80 percent of all science-focused CubeSats have been launched in the past 4 years. Similarly, more than 80 percent of the peer-reviewed papers describing new science results based on CubeSat data have been published in the past 5 years. Some of the disciplines where CubeSats appear to have much promise (i.e., Earth sciences) have only recently begun exploring CubeSats as a scientific platform.
Since 2012, there has also been a rapid growth in commercial applications using CubeSats, with venture-funded companies such as Planet Labs and Spire focusing on providing data products and services. The industry supporting CubeSat components and technologies is also growing and taking advantage of the increased market size by designing and selling CubeSat and small spacecraft buses, subsystems, and ground station services. These commercial firms are now major drivers of development in technologies such as attitude control and propulsion, as well as subsystems such as power boards and communication systems standardized to the CubeSat form factor. Some of this technology can now be purchased off the shelf and is available for science teams that seek to employ CubeSats to address science questions. Development kits are now available that provide an entry point for newcomers, or such groups may partner with companies that sell spacecraft buses along with payload integration, test, and mission operations. These advances in purchased spacecraft subsystems and common software now permit a science-driven CubeSat mission to focus primarily on development of the science instrumentation.
SCIENCE PROMISE OF CUBESATS
Based on the review of the scientific literature and inputs from a broad range of scientific communities, the committee concluded that CubeSats have already proven themselves to be an important scientific tool. CubeSats can produce high-value science, as demonstrated by peer-reviewed publications that address decadal survey science goals. They are useful as targeted investigations to augment the capabilities of large missions and ground-based facilities, are enabling new kinds of measurements, and may have the potential to mitigate gaps in measurements where continuity is critical. Although all science disciplines can benefit from innovative CubeSat missions, CubeSats cannot address all science objectives and are not a low-cost substitute for all platforms.
Some activities, such as those needing large apertures, high-power instruments, or very-high-precision pointing, most likely will always require larger platforms because of fundamental and practical constraints of small spacecraft. Also, large spacecraft excel at large-scale investigations, when, for example, several instruments need to be collocated. CubeSats excel at simple, focused, or short-duration missions, missions that need to be low cost, or those that require multipoint measurements.
Sample Science Goals
Because of their size, cost, and length of development cycle, CubeSats can transform the conduct of space science in two ways. First, they can enable some fraction of science traditionally done by larger and more expensive platforms to be conducted in more cost-effective ways. Second, CubeSats can enable and support science not feasible with traditional missions. It is via constellations of dozens or even hundreds of CubeSats where the most transformational science might be enabled. In space physics and Earth science especially, high-cadence, simultaneous multipoint measurements are essential for studying complicated, highly coupled systems, and these kinds of investigations so far have not been feasible. CubeSat-based constellations have the potential to provide important and truly enabling science capabilities in astronomy and planetary sciences—for example, by using instruments with distributed apertures such as radio interferometers.
The set of scientific goals where the use of CubeSats would be enabling is evolving too quickly for the committee to create a comprehensive list, and this committee was not tasked with prioritizing CubeSat missions. However, the following list, restated from Chapter 4, provides a sampling of high-priority science goals that could potentially be pursued using CubeSats:
- Solar and space physics, Earth science and applications from space—Exploration of Earth’s atmospheric boundary region. CubeSats are uniquely suited because of their expendability to explore the scientific processes that shape the upper atmospheric boundary using short-lifetime, low-altitude orbits.
- Solar and space physics—Measurement of plasma processes in the magnetosphere-ionosphere system. A 10-100 satellite constellation of CubeSats carrying magnetometers and plasma instrumentation can provide detailed information about the spatial and temporal evolution of magnetospheric plasmas.
- Earth science and applications from space—Multipoint, high temporal resolution of Earth processes. Satellite constellations in low Earth orbit could provide both global and diurnal observations of Earth processes that vary throughout the day, such as severe storms, and are currently under-sampled by Sun-synchronous observatories.
- Earth science and applications from space—Mitigation of data gaps and continuous monitoring. Anticipated and potential gaps (caused by launch or instrument failures and budget constraints) in weather satellite data, land surface imaging, and solar irradiance measurement may have the potential to be mitigated by observations from small spacecraft enabled by CubeSat technology.
- Planetary science—Measuring the distribution of lunar water. CubeSat concepts could map the distribution of water on the Moon with a variety of complementary techniques, such as neutron spectroscopy and infrared spectroscopy.
- Planetary science—In situ investigation of the physical and chemical properties of planetary surfaces or atmospheres. Deployable (daughter-ship) CubeSats could expand the scope of the motherships with complementary science or site exploration.
- Planetary science—Measurements of planetary magnetospheres. Constellations of CubeSats could provide simultaneous fields and particle measurements at multiple sites in planetary magnetospheres. Such measurements in the vicinity of large icy satellites could help determine the magnetic field induced in deep oceans.
- Astronomy and astrophysics—Search for extrasolar planets. A CubeSat could “stop and stare” for a long time at one bright Sun-like star to search for transiting exoplanets.
- Astronomy and astrophysics, solar and space physics—Low-frequency radio science. Interferometers made of CubeSats could explore the local space environment and also galactic and extragalactic sources with spatial resolution in ways not accessible from Earth.
- Biological and physical sciences in space—Investigate the survival and adaptation of organisms to space. CubeSats offer a platform to understand the effects of the environment encountered in deep space, such as microgravity and high levels of radiation.
As CubeSat-enabled missions evolve, the programs and management processes that currently fund and support them will have to evolve as well. The scientific potential offered by CubeSats continues to depend on investments in a number of programs, including the National Science Foundation (NSF), where the first CubeSat-based science program originated; NASA, where most CubeSats programs reside currently; and the Department of Defense Air Force Research Laboratory, which supports a large fraction of technology development and education efforts. During the ongoing, rapid expansion of scope and capability of this disruptive platform, the programmatic investments would benefit from continued broad access and also rapid dissemination of lessons learned among the different agency programs and the commercial sector, both of which will be addressed in subsequent recommendations to NSF and NASA.
The first such recommendation focuses on the CubeSat program that is part of NSF. This program has the dual goals of supporting small satellite missions to advance space weather-related research and of providing opportunities to train the next generation of experimental space scientists and aerospace engineers. The committee believes that the program has been successful with regard to both goals, and NSF’s current program continues to be valuable. The program is particularly well aligned with the goals and recommendations of the 2013 decadal survey in solar and space physics; however, other disciplines at NSF, such as Earth science and astronomy and astrophysics, could also benefit from the scientific and educational opportunities that CubeSats provide.
Recommendation: The National Science Foundation (NSF) should continue to support the existing CubeSat program, provide secure funding on a multiyear basis, and continue to focus on high-priority science and the training of the next generation of scientists and engineers. In particular, NSF should consider ways to increase CubeSat opportunities for a broad range of science disciplines going beyond solar and space physics, with financial support from those participating disciplines.
Although most science results published to date have come from NSF-sponsored CubeSat investigations, that is expected to change within the next few years as a result of NASA’s increased interest in CubeSats. NASA is developing at least 13 science-focused CubeSats, sponsored from five or more different NASA programs. Several science communities are still in the very early phases of learning to design and operate CubeSats, while others are actively developing promising science missions. The current diversification and rapid expansion of CubeSats within NASA are characteristic of the early phase of disruptive innovation, as discussed in Chapter 2.
CubeSats have proven their usefulness in the pursuit of science, most notably demonstrated by the increase in the publication of scientific results as described in Chapter 4 and Appendix B. The explosion of interest in the deployment of CubeSats and proliferation of NASA programs that sponsor CubeSat missions has led to some inefficiencies. For example, a university group interested in becoming involved with CubeSats might find it difficult to identify the best opportunities and NASA partners for the desired endeavor. Similarly, a company with interesting new technologies does not have a clear pathway to make those products available to all of the different teams. In addition, the committee encountered multiple instances where more than one mission team within NASA
was independently developing the same technology: examples include laser communications, cold-gas propulsion systems, and the ability to modify the orbits of multiple spacecraft by atmospheric drag.
Conclusion: The rapidly increasing potential of CubeSats as a platform for scientific discovery translates into a need for better coordination and management at NASA. Spacecraft development, launch and radio license approvals, technology development, and mission operations efforts to support scientific CubeSat missions are being duplicated at multiple centers and at investigator facilities.
Other existing programs within NASA (e.g., the sounding rocket and balloon programs) provide examples of possible management approaches. The committee believes that the following three aspects of those programs are relevant to CubeSats: (1) the program office provides a single point of contact within NASA and support for technical and policy related issues common to a given platform; (2) the program office creates an appropriate level of oversight matched with the development cycle and risk profile of balloons and rockets, respectively; and (3) the program office becomes a champion within NASA and the science community. However, one should not push these analogies too far as CubeSat missions face different technical and programmatic challenges from those of sounding rockets and balloons.
Recommendation: NASA should develop centralized management of the agency’s CubeSat programs for science and science-enabling technology that is in coordination with all directorates involved in CubeSat missions and programs, to allow for more efficient and tailored development processes to create easier interfaces for CubeSat science investigators; provide more consistency to the integration, test, and launch efforts; and provide a clearinghouse for CubeSat technology, vendor information, and lessons learned. The management structure should use a lower-cost and streamlined oversight approach that is also agile for diverse science observation requirements and evolutionary technology advances.
Centralized management should make it possible to increase the overall scientific return and advance sophisticated uses of CubeSats such as large constellations. At the same time, it is important to encourage innovation by maintaining a variety of programs.
Recommendation: NASA should develop and maintain a variety of CubeSat programs with cost and risk postures appropriate for each science goal and relevant science division and justified by the anticipated science return. A variety of programs are important to allow CubeSats to be used for rapid responses to newly recognized needs and to realize the potential from recently developed technology.
For example, a solar and space physics-focused CubeSat with a short development cycle and lower cost might be able to take rapid advantage of a technological breakthrough. On the other hand, a CubeSat flying as part of a planetary science mission might be developed on the same timescale as the larger spacecraft of the mission and require higher reliability, which is typically associated with higher cost.
Education and Training
One critical benefit of NASA’s engagement in CubeSats is the role of CubeSats in training students, early career project scientists, engineering teams, and project managers. Care must be taken to not inadvertently stifle such training opportunities as CubeSats evolve toward more-capable science missions and as the proposed new management structure is implemented.
Recommendation: NASA should use CubeSat-enabled science missions as hands-on training opportunities to develop principal investigator leadership, scientific, engineering, and project management skills among both students and early career professionals. NASA should accept the risk that is associated with this approach.
There is one type of mission class that is of high priority for multiple disciplines and which deserves focused investment and development—the creation of swarms and constellations for high-priority measurements. As discussed in detail in Chapter 4, constellations are of high priority in the decadal survey for solar and space physics, a community that has evolved from single space missions to research that requires data from multiple missions, toward an approach of two to five identical spacecraft that are analyzed as a constellation. Many high-priority science investigations of the future require data from constellations or swarms of 10 to 100 spacecraft that, for the first time, would have the spatial and temporal coverage to map out and characterize the physical processes that shape the near Earth space. Constellations are also critical to Earth science, in which the number of spacecraft relates directly to coverage and temporal evolution of a given phenomenon. Similarly, some constellation-based missions have also been discussed for astrophysics or planetary applications. Because of these and several other opportunities across the science disciplines for high-priority science by constellations and swarms, the time is ripe to develop this new capacity. The Cyclone Global Navigation Satellite System (CYGNSS) Earth Venture mission with eight LEO spacecraft—small, but not CubeSats—is an important step for science constellation development. NASA, with its distributed ground systems and established new mission opportunities, can further advance the capabilities for constellation and swarm science missions. Historically, the cost associated with large constellations for spacecraft numbers between 10 to 100 spacecraft has been prohibitive.
Recommendation: Constellations of 10 to 100 science spacecraft have the potential to enable critical measurements for space science and related space weather, weather and climate, as well as some astrophysics and planetary science topics. Therefore, NASA should develop the capability to implement large-scale constellation missions taking advantage of CubeSats or CubeSat-derived technology and a philosophy of evolutionary development.
Since the beginning of the CubeSat missions in 2000, the capacity to do science with CubeSats strongly depends on the technological capabilities available to the investigators. CubeSat technology advances are markedly noticeable since 2008 when government funding of CubeSat technology and missions began, and many science CubeSat missions are now in development by NSF and NASA. Nonetheless, the spacecraft technology capabilities are currently limiting the use of CubeSats in some science applications.
Conclusion. The key gaps in technology related to CubeSats for science applications are high bandwidth communications, precision attitude control, propulsion, and the development of miniaturized instrument technology.
If these capabilities can reach maturity, they will be able to support flight formation, orbital deployment and maintenance, precise pointing for persistent and high-resolution observations, and high-bandwidth communications. One important benefit of such developments is that they enable missions that consist of constellations or swarms of CubeSats or CubeSat-technology enabled satellites. See Chapter 4 and Table 5.1 for details of specific scientific applications of these enabling technologies.
Recommendation: NASA and other relevant agencies should invest in technology development programs in four areas that the committee believes will have the largest impact on science missions: high-bandwidth communications, precision attitude control, propulsion, and the development of miniaturized instrument technology. To maximize their impact, such investments should be competitively awarded across the community and take into account coordination across different agencies and directorates, including NASA’s Science Mission Directorate and Space Technology Mission Directorate, and between different NASA and Department of Defense centers.
An additional area of technology development that is important to several disciplines is thermal control, a much broader, system engineering-related topic than are those recommended above. Aspects of thermal control vary from maintaining low temperatures for imaging spectrometers to creating a stable payload environment for biology experiments with live specimens.
One benefit of CubeSat technology developments is the maturing of specific instrumentation and space technologies available to spacecraft that are not necessarily consistent with the CubeSat norm. There are already numerous applications for Explorers or Venture-class missions that benefit from the availability of technologies developed for CubeSats either commercially or by federal research and development programs.
Conclusion: CubeSats have been and will likely remain an important and cost-effective in-space platform for research, development, testing, and demonstration of technologies relevant to scientific discovery.
The private sector has been growing both in terms of capabilities in and investments for CubeSat applications and is likely to remain an important partner in technology development programs for small satellites. However, in some areas, private-sector investments are less likely to occur, such as infrastructure and facilities (e.g., a test and prototyping center); development of deorbiting; tracking and other technologies related to orbital debris reduction goals; and approaches to enable affordable launch for CubeSats.
Recommendation: As part of a CubeSat management structure, NASA should analyze private capabilities on an ongoing basis and ensure that its own activities are well coordinated with private developments and determine if there are areas to leverage or that would benefit from strategic partnerships with the private sector.
Although CubeSats are only a small fraction of the cost, mass, and complexity of other spacecraft launched by commercial and government entities, they are subject to a comparable policy framework. If applied improperly and without consideration of the short development cycle, low costs, and rapid increase in the number of commercial, technology, and science CubeSats, such policy constraints could have a chilling effect on the scientific and technology return of CubeSats.
The committee focused principally on three policy issues that have the potential to limit the applicability of CubeSats for science—orbital debris, communications and frequency allocations, and launch availability—including, in particular, regulatory framework.
Finding: Because CubeSats typically are not maneuverable, they are seen as orbital debris threats, especially in near Earth orbits, with low Earth orbit being a special challenge because of the presence of the International Space Station. CubeSats comprise less than a percent of all resident objects in space and are expected to remain a small fraction, even as their number in space grows. The number of science-focused CubeSats is an order of magnitude lower than that.
Conclusion: Although CubeSats are a very small fraction of all resident objects in space, the risk of a CubeSat conjunction or collision is not insignificant. Thus, the CubeSat community has an opportunity to avoid potential future problems by continuing to proactively engage in policy discussions and seek technological solutions, such as low-cost means for CubeSats to be maneuverable, trackable, and deorbited appropriately.
Communications and Frequency Allocation
Conclusion: Spectrum licensing for CubeSats is required and can be complicated and time-consuming. The increasing use of CubeSats for science will likely also increase the need for higher bandwidth, further complicat-
ing the licensing difficulty. This will remain a problem for the growing CubeSat community. CubeSat developers will likely rely extensively on experimental licenses, because a permanent long-term solution for the CubeSat “bandwidth crunch” is not in sight. Because experimental licenses are always issued on a noninterference basis, their use will create an additional element of risk for CubeSat developers.
Conclusion: As of the end of 2015, most CubeSats have been deployed as secondary payloads on large rockets. This can be cost-effective, but it is also limiting the variety of orbits available for science CubeSats. There are many entities offering vehicles for launch of smaller payloads, including CubeSats. However, their success is uncertain, and low-priced launch remains an elusive target for CubeSats. NASA supports the launch of scientific and educational CubeSats, but there is a backlog of requests for launches. Thus, low-cost launch remains a barrier for the deployment of scientific and educational CubeSats.
Recommendation: NASA, with the National Science Foundation, and in coordination with other relevant federal agencies, should consider conducting a review and developing a plan to address CubeSat-related policies to maximize the potential of CubeSats as a science tool. Topics may include, but are not limited to, the following: guidelines and regulations regarding CubeSat maneuverability, tracking, and end-of-mission deorbit; the education of the growing CubeSat community about orbital debris and spectrum-licensing regulatory requirements; and the continued availability of low-cost CubeSat launch capabilities. It is important to consider that current and new guidelines promote innovation, rather than inadvertently stifling it, and ensure that new guidelines are science-based, equitable, and affordable for emerging players within the United States and internationally.
BEST PRACTICES TO GUIDE ONGOING CUBESAT DEVELOPMENT
History has shown that the likelihood of success and economic impact of potentially disruptive innovations, such as CubeSats, is difficult to predict in the early days of the disruption. At this point, it seems that CubeSats will become an effective tool for a specific and eventually well-defined performance envelope, like balloons or sounding rockets. However, it is possible that CubeSats will have a much bigger impact and lead to new types of missions and scientific data, and perhaps even lead to a more macroscopic realignment of the space industry. The principles of disruptive innovations informed the above recommendations and also led the committee to suggest some best practices that can guide the ongoing development of CubeSats.
- Avoid premature focus. Although the committee recommends a NASA-wide management structure to create opportunities for new investigators and provide a clearinghouse for information and lessons learned, premature top-down direction that eliminates the experimental, risk-taking programs would slow progress and limit potential breakthroughs.
- Maintain low-cost approaches as the cornerstone of CubeSat development. It is critical to resist the creep toward larger and more expensive CubeSat missions. Low-cost options for CubeSats are important because more constrained platforms and standardization, coupled with higher risk tolerance, tend to create more technology innovation in the long run.
- Manage appropriately. As missions grow more capable and expensive, management and mission assurance processes will have to evolve. Yet, it is critical to manage appropriately, without burdening low-cost missions with such enhanced processes, by actively involving CubeSat experts in policy changes and discussions as well as in proposal reviews.
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