There are several challenges that could adversely affect the development of science-focused CubeSats. The principal ones include the reality and the perception of CubeSats generating orbital debris, spectrum challenges, and difficulties related to obtaining affordable access to space. This chapter discusses each of these multifaceted challenges, especially as they affect the future of CubeSats as science platforms.
Background on Orbital Debris
Any object in orbit around Earth that no longer serves any useful purpose is referred to as orbital debris. This includes spent rocket stages, old satellites, and fragments as small as paint particles.1 While there are only about 1,300 active spacecraft in orbit, there are estimated to be about 500,000 objects between 1 and 10 cm in diameter and more than 100 million particles smaller than 1 cm that are not systematically tracked.2 Although the probability of accidental collisions is low, at relative impact velocities greater than 35,400 km per hour, debris as small as half a centimeter across can substantially damage a spacecraft.3
The U.S. Air Force’s Joint Space Operations Center (JSpOC) tracks about 23,000 objects in space larger than around 10 cm in diameter and provides close approach warnings to all satellite operators. In 2014, JSpOC provided an average of 23 “emergency” notifications per day (almost 700,000 possible collision warning notifications were provided throughout the year to satellite owners and operators4), and operators performed hundreds of avoidance maneuvers to reduce risk of potential collisions. In addition, during 2014, NASA executed or assisted
1 J.-C. Liou, 2012, “The Near-Earth Orbital Debris Problem and the Challenges for Environment Remediation,” presented at the 3rd International Space World Conference, Frankfurt, Germany, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120012893.pdf.
3 SpaceRef Business, “NewSpace 2014 Conference—Day 3 Video,” posted July 28, 2014, http://spaceref.biz/organizations/space-frontier-foundation/newspace-2014-conference---day-3-video.html.
in the execution of more than two dozen collision-avoidance maneuvers by robotic spacecraft.5 Because of the risk of collision, the International Space Station (ISS) has had to conduct 25 collision-avoidance maneuvers since 1999.6 NASA, analyzing data from six space agencies, estimates that there will be a catastrophic collision every 5 to 9 years. Managing orbital debris is therefore an important challenge for the entire space community.
CubeSats as an Orbital Debris Challenge
To date, CubeSats have not been a significant part of the orbital debris challenge. As Figure 6.1 shows, there are about 155 CubeSats in low Earth orbit (LEO). As such, they comprise a very small fraction of objects 10 cm and larger—approximately 1 percent of the current resident space objects catalog. Even with optimistic projections with respect to CubeSat launches (see later this chapter), CubeSats will remain a very small fraction of objects in space.7 Scientific CubeSats are an even smaller fraction (Figure 1.3), with much of the future growth expected to be in the commercial sector.
5 J.-C. Liou, NASA, “USA Space Debris Environment, Operations, and Measurement Updates,” presentation to the 52nd Session of the Scientific and Technical Subcommittee, Committee on the Peaceful Uses of Outer Space, United Nations, February 2-13, 2015, http://www.unoosa.org/pdf/pres/stsc2015/tech-28E.pdf.
7 The number of debris objects larger than one centimeter will reach around 1 million in year 2020 (European Commission 2013). About 2,000-2,750 micro/picosatellites are projected to be launched through 2020. It is not known how many of these will be CubeSats.
With one exception, a picosatellite release from a Peruvian 1U CubeSat, all CubeSat-related objects in orbit are successfully tracked by JSpOC.8 To the best of the committee’s knowledge, while there have been some conjunction warnings related to CubeSats, only one spacecraft has had to maneuver out of the way of a CubeSat. And while the ISS has had several conjunctions or close approaches with CubeSats, only one has led to a maneuver, indirectly.9 All NASA- and NSF-funded CubeSats have complied with the guideline that satellites deorbit within 25 years after mission completion.10 Also, the average lifetime of the 126 CubeSats that have decayed is approximately 290 days, with a max of 1,340 days and minimum of only 2 days. On the debris remediation front as well, as Figure 6.2 shows, given the size distribution of objects, experts propose11 that the focus be on either large
8 Correspondence with JSpoC; NASA, Orbital Debris: Quarterly News Volume 19, Issue 3, July 2015, http://orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv19i3.pdf.
9 Personal correspondence with NASA; NASA, Orbital Debris: Quarterly News Volume 19, Issue 3, July 2015, http://orbitaldebris.jsc.nasa.gov/newsletter/pdfs/ODQNv19i3.pdf.
10 In February 2007 and after a multiyear effort, the IADC (Inter-Agency Space Debris Coordination Committee), created under the aegis of the United Nations’ Committee on the Peaceful Uses of Outer Space (COPUOS), adopted a set of space debris mitigation guidelines which includes a 25-year deorbit requirement from low Earth orbit. The guidelines were accepted by the COPUOS in June 2007 and endorsed by the United Nations in January 2008, http://www.unoosa.org/documents/pdf/spacelaw/sd/IADC-2002-01-IADC-Space_Debris-GuidelinesRevision1.pdf.
11 J.-C. Liou, NASA, “Orbital Debris Mitigation Policy and Unique Challenges for CubeSats,” presentation to the committee on October 30, 2015.
objects (>100 cm, which can be tracked and may become a source of small objects) or very small ones (<1 cm, where shielding can mostly mitigate effects), with secondary focus on CubeSat-sized objects (1-10 cm, which are difficult to track and not easy to shield against) (Figure 6.2).
Despite the record to date of minimal CubeSat related conjunctions and debris avoidance maneuvers and no collisions to date, and the recommendation by experts to focus on the far ends of the size spectrum rather than the CubeSat range, as the number of CubeSats grow,12 there is growing concern that CubeSats may become a space debris hazard.13 This could be an issue because, in theory, CubeSats do not necessarily have a lower collision risk (collision probability is a function of the combined radius of the CubeSat and the larger body with which it might collide, not just the smaller object).14 If there were to be a collision related to a CubeSat, even if it is not a science CubeSat, it may be detrimental to all users of CubeSats as a science, technology, or commercial platform.
Given this risk, even a nonscience CubeSat involved in a collision may result in the creation of an onerous regulatory framework and affect the future disposition of science CubeSats. Therefore, it befits the science community to take the risk of any conjunctions seriously—not just those of science CubeSats. In this section, the committee briefly discusses the challenges CubeSats face with respect to orbital debris and what measures may be considered to address these challenges. It is important to note here that these challenges apply to an even greater extent to larger satellites, and thus, CubeSats can serve as an innovation platform for broader benefit.
There are three major orbital debris challenges related to CubeSats (for more technology-related details, refer to Appendix C and Chapter 5). The first relates to mobility or maneuverability. Most CubeSats do not have onboard propulsion. As a result, CubeSats cannot maneuver out of the way if they come across other space objects such as the ISS. While is it not unusual for spacecraft to be non-maneuverable, this puts the onus of maneuvering out of the way on the other object, which can become expensive for the operator. They have to expend more propellant, which will shorten the spacecraft lifetime and reduce either science returns or commercial revenue, and their insurance cost might increase,15 for example.
The second challenge relates to “trackability.” There is no specific requirement that any spacecraft carry active (e.g., transponder) or even passive (e.g., RFID, retro-reflectors) tracking devices. Lack of such devices makes it difficult to track them and presents an increased risk of collision. Tracking is even more important when CubeSats are launched in clusters (e.g., from the ISS), because their separation times are long, which adds to the workload of entities assigned to track space objects, such as JSpOC.
The third challenge relates to a CubeSat’s end of life. Most CubeSats today, by design or otherwise, stop working after a few months or years of operation. However, they stay in orbit for a long time and not all are in compliance with the 25-year guideline mentioned above.
It is worth noting that there are no domestic or international norms on maneuverability or the ability to track or deorbit CubeSats or other satellites. Neither are there any agreed-upon norms as to how CubeSat constellations will be designed, manufactured, deployed, or operated (beyond what is the case for all satellites), domestically or globally.
12 Planet Labs is expected to launch 250 CubeSats in 2016.
13 P. Marks, “CubeSat craze could create space debris catastrophe,” New Scientist, release date September 24, 2014, https://www.newscientist.com/article/mg22329882-500-cubesat-craze-could-create-space-debris-catastrophe/; I. O’Neill, “CubeSats: A Space Junk Hazard?”, Discovery News, release date September 30, 2014, http://news.discovery.com/space/cubesats-a-space-junk-hazard-140930.htm; S. Clark, “NASA: Tracking CubeSats is easy, but many stay in orbit too long,” Spaceflight Now, release date July 30, 2015, http://spaceflightnow.com/2015/07/30/nasa-tracking-cubesats-is-easy-but-many-stay-in-orbit-too-long/; J. Rotteveel, “Another View on CubeSats and Debris,” SpaceNews Commentary, release date October 27, 2014, http://spacenews.com/42329another-view-on-cubesats-and-debris/; A. Anzaldua and D. Dunlop, “Overcoming non-technical challenges to cleaning up orbital debris,” The Space Review, release date November 9, 2015, http://www.thespacereview.com/article/2863/1; G. Harris, “Space debris expert warns of increasing CubeSat collision risk,” Phys Org, release date September 30, 2014, http://phys.org/news/2014-09-space-debris-expert-cubesat-collision.html.
14 Indeed, analyses show that the collision risk between a large satellite and a CubeSat is not significantly lower than the risk between a large satellite and a 1 m2 object. A.J. Abraham, and R.C. Thompson, The Aerospace Corporation, 2015, “CubeSat Collision Probability Analysis,” presentation at the Small Payload Ride Share Association Conference, https://www.sprsa.org/sites/default/files/conference-presentation/Cubesat_Probability_Charts_v2.3.pptx.
15 According to the European Commission, satellite operators in Europe lose approximately $152 million per year due to collisions, and that total is predicted to rise to about $228 million within the next decade. S. Cruddas, “Cleaning Up Space,” RAeS Quarterly, Summer 2015, Royal Aeronautical Society Quarterly Newsletter, Washington D.C. Branch, http://raeswashingtondcbranch.cloverpad.org/Resources/Documents/RAeS_15_Summer_Quarterly_Newsletter.pdf, p. 12.
Operators, and others tasked with tracking space objects, propose several actions that can be taken, together or individually, to address the potential challenge of orbital debris from CubeSats. The first action is to give CubeSats some level of onboard propulsion to allow them to maneuver out of the way if needed, with all of the technical challenges already discussed in Chapter 5 and Appendix C.
A second action is to ensure that CubeSats are trackable. This could be done with greater coordination between operators and trackers (e.g., JSpOC) so the latter can track CubeSats more precisely (e.g., provide detailed information on launch plans and payload deployment to ensure that individual CubeSats are quickly identified upon separation or release from the payload deployer).16 Planet Labs publicly disseminates its ephemerides, which could be one potential good practice to consider. Further orbital zoning has also been recommended to promote ease of tracking. As discussed in the technology chapter above, the challenge can also be addressed by technology—for example, the use of active and passive tracking devices (see Appendix C for more details).17
A third action is to ensure that, given the probability, however low, that they may collide with other objects, CubeSats deorbit soon after they stop working instead of staying in orbit for the full, allowed lifetime of 25 years.18 In the domain of orbital debris removal, there are also proposals for active debris removal (ADR) or the active rehabilitation (ADRe) of defunct spacecraft, but they apply less to CubeSats than they do to larger satellites.
Given that there is no CubeSat-specific domestic or international regime that can require CubeSats to be maneuverable, trackable, or deorbited appropriately,19 it may be feasible to put voluntary agreements or standards in place and have designers, manufacturers, or launchers impose requirements. It is important to note that the CubeSat community is international, and U.S.-only rules will not suffice.20 For example, there are more U.S. CubeSats launched on foreign vehicles (38 out of 108) than foreign CubeSats launched on U.S. vehicles (1 out of 116). As a result, having U.S. launch providers impose rules will not shift the system. However, there may be an opportunity for the United States, perhaps in coordination with Europe and Japan, to take a leadership role in setting best practices.
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.
In the United States, transmitting radio signals to or from a space object (including a CubeSat) requires regulatory approval. The requirement to obtain a license applies to all CubeSats that transmit, regardless of orbit or
16 Recommendations from a government representative.
19 Although there are domestic and international policies, guidelines and requirements related to orbital debris mitigation apply to all satellites, including CubeSats. These include NASA Procedural Requirements for Limiting Orbital Debris, the U.S. Government Orbital Debris Mitigation Standard Practices, the IADC Space Debris Mitigation Guidelines, and the UN Space Debris Mitigation Guidelines.
20 “International coordination would be required for any sustained effort to capture and remove debris because many nations have contributed to the problem and the United Nations 1967 Outer Space Treaty states that space-based objects, including spent rocket boosters and satellite fragments, belong to the nation or nations that launched them.” D. Werner, “NASA’s Interest in Removal of Orbital Debris Limited to Tech Demos,” release date June 22, 2015, http://spacenews.com/nasas-interest-in-removal-of-orbital-debris-limited-to-tech-demos/.
final destination. Simply put, it is illegal for a space object to emit any type of radio signal, or for an Earth station to transmit to a satellite from the ground, without authorization.21 Unfortunately, the methods and procedures for obtaining appropriate authorization are spread among voluminous rules and regulations issued by domestic regulatory authorities and are also subject to additional regulations established through international treaties (see Appendix C). Understandably, few CubeSat developers are familiar with the details of these rules, but discovery too late in the development process creates substantial risk that a CubeSat project will be denied a ride to space.
CubeSat developers and operators face a number of challenges in obtaining the needed regulatory approvals. Among them are the following:
- The timescale for obtaining satellite and Earth station licenses can be substantially longer than the development cycle for a CubeSat. The filings to obtain satellite and Earth station licenses are not particularly streamlined, and most CubeSat developers will have no prior experience navigating the process.
- Every desirable frequency in the radio spectrum is already being used. Satellite visibility covers a very large footprint on the surface of Earth, so their transmissions must be coordinated over large areas with potentially many other users.
- CubeSat developers tend to favor lower frequencies, where equipment is less expensive and more readily available, but lower frequencies are the most congested parts of the radio spectrum. Even if a developer can obtain coordination for the use of such frequencies, they will typically be faced with substantial interference from other users when trying to receive weak signals from their satellite.
- Traditionally, the regulatory authorities prefer to know details of satellite orbits, such as elevations and inclinations, when filings are made, but these parameters may be uncertain for some CubeSats until late in the process.
Although the U.S. and international regulatory authorities are becoming more aware of the challenges facing small satellite spectrum use, they have so far declined to change their rules to better accommodate these systems. Instead, it is incumbent upon the CubeSat community to understand the challenges and opportunities of the existing regulatory structure and to become more aware of how this structure will impact their development and operational plans.
CubeSat Spectrum Use
To date, CubeSat developers and operators have used a variety of options to obtain spectrum authorizations (Appendix C provides some background information on spectrum related issues). In an examination of CubeSat spectrum use from 2009 through March 2015,22,23 the following breakdown of licensing schemes was revealed:
- 53 percent were licensed as amateur radio satellites, through the Federal Communications Commission (FCC);
- 26 percent were authorized under FCC experimental licenses;
- 9 percent were authorized as federal government satellites through the National Telecommunications and Information Administration (NTIA);
- 6 percent were licensed through the FCC under a particular radio service other than amateur-satellite, including Earth exploration-satellite, meteorological satellite, and space research services; and
- 6 percent were either not licensed or their license status could not be determined.
21 Station Authorization Required, 47 C.F.R.§ 25.102(a) (2010).
22 B. Klofas, and K. Leveque, 2013, “A Survey of CubeSat Communication Systems: 2009-2012,” http://www.klofas.com/papers/Klofas_Communications_Survey_2009-2012.pdf; B. Klofas, “CubeSat Communications System Table,” updated March 10, 2015, http://www.klofas.com/comm-table/.
23 The statistics include the Planet Labs Flock-1 release of 28 satellites counted as 1 instance of licensing as Earth Exploration. Such large-scale commercial operations typically employ a team of legal experts that acquire licensing through the FCC under an appropriate service, an option normally not available to the science-focused CubeSat developer because of expense and because timescale to deployment is usually much shorter than for commercial operations.
Each of these licensing schemes is discussed below.
Amateur Radio Licensing
The amateur-satellite service is allocated many bands throughout the radio spectrum. Three particularly popular bands for CubeSat use are 144-146 MHz, 435-438 MHz, and 1260-1270 MHz. The use of amateur radio frequencies is, on the face of it, very appealing for the following reasons:
- Any individual may obtain an amateur radio license upon passing an examination. While the examination is not particularly easy, it is well within the reach of students, educators, faculty, and technicians typically involved in CubeSat projects.
- Licensed amateur radio operators are granted blanket authorization to use any appropriately allocated amateur radio frequency. Therefore, CubeSat teams that include a licensed amateur radio operator can use that operator to communicate with the satellite, with no additional licensing requirements, subject to a significant caveat discussed below.
- Thousands of amateur radio operators in the United States, and many more abroad, possess suitable equipment for listening to CubeSat transmissions. Therefore, an extensive and readily available worldwide network of volunteer Earth stations is available.
- Amateur radio equipment (both for the satellite and for the Earth stations) is relatively inexpensive and readily available.
However, there are several significant drawbacks to using the amateur-satellite service:
- Amateur radio communications are generally limited to transmissions necessary to exchange messages with other stations in the amateur service.24
- Amateur radio licensees may not use amateur radio for any communications in which they have a pecuniary interest.25 Therefore, amateur radio operators that are paid members of a CubeSat team or receive a stipend or tuition are not abiding by the amateur radio rules.
- Amateur radio satellites must coordinate on an international basis through the International Amateur Radio Union (IARU), a volunteer group, to avoid interference to existing amateur and planned operations.
- Limited bandwidth is available. Within the two most popular bands (144-146 and 435-438 MHz), only a total of 5 MHz of bandwidth is available.
- With the limited bandwidth and the need to coordinate frequencies, the use of amateur-satellite spectrum for CubeSats is not sustainable, given the anticipated growth in the number of CubeSat launches. The amateur-satellite service has been accustomed to a handful of operational amateur satellites at one time. Dozens or hundreds more CubeSats (both domestic and international) would overwhelm the available bandwidth at the lower frequencies.
The FCC provides for the issuance of experimental licenses for terms of 6 months to 5 years. Such authorizations may be provided for a variety of purposes, including the following that are relevant to CubeSats:26
- Experimentations in scientific or technical radio research;
- Experimentations under contractual agreement with the U.S. government, or for export purposes;
- Communications essential to a research project; and
- Technical demonstrations of equipment or techniques.
24 Station Authorization Required, 47 C.F.R.§ 97.111 (2010).
25 Station Authorization Required, 47 C.F.R.§ 97.113 (2010).
26 Station Authorization Required, 47 C.F.R.§ 5.3 (2010).
The use of experimental licenses is advantageous for two main reasons:
- Authorizations are typically granted more expeditiously than for traditional licensing; and
- Experimental licenses may utilize any frequency in the spectrum, including government or nongovernment frequencies, upon proper justification.
The use of experimental licenses has the significant drawback, however, that such operations are on a noninterference basis. If such operations cause interference to other services, transmissions must be stopped until the situation is rectified.27 Stations operating under experimental licenses must also accept interference caused to them by stations operating under regular authority.
While approximately 26 percent of CubeSats (2009 through March 2015) have operated under experimental licenses, many of these satellites utilized amateur radio spectrum. This licensing method leveraged the benefits of using amateur radio spectrum while avoiding the limitations on the use of amateur communications for pay.
Federal Government Authorization
NTIA, instead of the FCC, authorizes transmissions from federal government stations. If a CubeSat qualifies as a government satellite, it may utilize the NTIA process. What exactly constitutes a government satellite is not precisely defined, however. Generally, considerations may include the following:
- What entity positively controls the transmissions emanating from the satellite and its associated Earth stations?
- Who funded the CubeSat?
- Who owns and operates the Earth station facilities?
The first consideration is important. Although a CubeSat may be fully funded by the National Science Foundation (NSF) or NASA, if the satellite and Earth station transmissions are operated by an academic institution, and thus NSF or NASA does not have full control, the satellite will not generally be considered a federal government satellite. There are some methods to satisfy the requirement, however. For example, if the satellite is funded by NSF and operated under a cooperative agreement where NSF retains full control of the satellite and Earth station facilities, the CubeSat may be considered a federal government satellite and authorized through the NTIA process.
The main advantage to obtaining an authorization through NTIA is that the CubeSat developer may leave most of the application process in the hands of government spectrum managers who perform such duties on a regular basis. For example, a NASA-funded CubeSat, if determined to be a federal government satellite, could utilize the standard NASA authorization process to obtain NTIA authorization, and this process is routine among NASA spectrum managers. An additional advantage is that the satellite may utilize federal government frequencies, which may be less congested than nongovernment frequencies are.
On the other hand, the NTIA authorization process can take a long time. Satellites must be certified first (a process through which NTIA determines that the satellite and Earth stations meet all technical rules and that sufficient spectrum resources are expected to be available). Only after the satellite and its Earth station(s) achieve certification may a particular frequency be applied for. The process of certification followed by frequency assignment can easily take more than 1 year, with the process involving collecting and submitting all relevant technical information, followed by submission to NTIA by a government agency, followed by analysis and action by NTIA, which, like most government agencies, has limited resources to deal with increasing workloads. The CubeSat application goes into a general queue that can include applications for major systems, such as air traffic control radars, federal law enforcement radio systems, weather satellites, general agency dispatch radio, and military satellite constellations, among hundreds of other systems processed by NTIA on an ongoing basis.
Very early in the development process, CubeSat developers have to talk with their agency sponsors to determine whether federal government spectrum authorizations are an option.
27 Station Authorization Required, 47 C.F.R.§ 5.111(a)(2) (2010).
Licensing Under Satellite Services
Only a small fraction of CubeSat developers have opted for licensing under a recognized non-amateur satellite service, such as the Earth exploration-satellite, space research, or meteorological-satellite services. Typically, licensing under the FCC’s “regular” satellite licensing process is utilized by major satellite systems whose development cycle takes years and whose satellite operations are expected to continue for many years. Although such licensing has the advantage of providing firm interference protections and regulatory certainty, it is also the most time-consuming, and potentially expensive, route to pursue, and operations generally are limited to bands specifically allocated to these services, whether the licensee goes through the FCC or the NTIA processes. The advantages of experimental licensing, as discussed above, typically outweigh the advantages of licensing under a recognized satellite service.
In the early days of CubeSats, a small number were apparently flown without any frequency authorization at all. The developers designed their satellites to utilize “unlicensed” or Industrial Scientific and Medical (ISM) spectrum bands, such as those used for cordless phones, Wi-Fi, baby monitors, microwave ovens, and other terrestrial devices that operate without a license requirement. Unfortunately, this use is forbidden under FCC and NTIA rules, as the concept of unlicensed or ISM spectrum use does not extend to space. All domestic CubeSats and their affiliated Earth stations must be licensed.
Future Spectrum Requirements
As CubeSats and their associated science goals become increasingly sophisticated, bandwidth requirements are likely to continue to grow. To date, most CubeSats have utilized downlink data rates similar to 1980s and 1990s vintage computer modems, at 1 to 57 kbps, with most around 9.6 kbps.28 (One CubeSat program, by virtue of access to a wider bandwidth satellite allocation, achieved ~2.6 or even 3.0 Mbps downlink speed, but that program was unique29 and beset by regulatory and interference challenges.30)
For LEO CubeSats, these data rates effectively translate to low total data downloaded over the life of the satellite, given the limited visibility of satellites from the surface of the Earth and, therefore, limited opportunities for data download. The total lifetime throughput for typical operational CubeSats to date range from a few hundred kilobytes to a few hundred megabytes.
In fact, total data throughput depends on signal bandwidth, and wider bandwidths are more challenging to fit within existing spectrum constraints, especially at frequencies below 1 GHz that are favored by CubeSat developers. It is reasonable to assume that as the science objectives of CubeSats become more ambitious, their bandwidth requirements—and associated regulatory challenges—will also grow. The most obvious solution to increased bandwidth requirements is to move to higher frequencies where more bandwidth is available, although this is accompanied by its own challenges, among them the following:
- Increased radio hardware cost,
- The need for directional antennas and associated pointing requirements,
- Lower power efficiency, and
- Coordination with a larger number of other spectrum users within the larger bandwidth.
28 B. Klofas, and K. Leveque, 2013, “A Survey of CubeSat Communication Systems: 2009-2012,” http://www.klofas.com/papers/Klofas_Communications_Survey_2009-2012.pdf.
29 NSF and NASA, 2013, National Science Foundation (NSF) CubeSat-Based Missions for Geospace and Atmospheric Research Annual Report, p. 7, NP-2013-12-097-GSFC, Arlington, Va., http://www.nsf.gov/geo/ags/uars/cubesat/nsf-nasa-annual-report-cubesat-2013.pdf.
30 J. Gunther, C. Swenson, and C. Fish, 2013, “‘High Data Rate’ Communications for DICE,” presented at CubeSat Developers’ Workshop, Cal Poly, http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2013/GroundStation_Workshop_Gunther_DICE.pdf.
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 complicating 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.
As discussed above, since 2000, more than 400 CubeSats have been launched through one of the following four alternatives: obtaining a rideshare or “piggyback” on board a vehicle with an established primary satellite; buying a dedicated small launch vehicle; ridesharing with a group of CubeSats on a “cluster launch”; and being a hosted payload permanently attached to another satellite. Roughly half of the launches to date have been just the first option—secondary payloads—on just three vehicles: U.S.-based Antares and Minotaur rockets and Russia-based Dneper. Going forward, however, the United States and Russia no longer have the nanosat launch market duopoly. Since 2014, nearly 300 nano- and microsatellites have been launched by 12 launch vehicle families in six countries (Figure 6.3).
Rideshares are often challenging for CubeSat operators because they have design constraints due to the “do no harm” requirement for secondary payloads. There are other downsides to ridesharing. CubeSat operators have no control over the orbit, and they have to go where the primary payload is going. Their schedule is also driven by the schedule of the primary payload.31
Only a small fraction of rockets carry small satellites (in the past 5 years, less than 15 percent of attempted launches had nano- or microsatellites [1-50 kg] payloads on board).32 Rideshares are not necessarily inexpensive either. Launch costs vary from free to $10 million.33 For those CubeSats where the development cost in the range of $10,000-$1,000,000, paying millions of dollars in launch costs is unrealistic.
Some low-cost opportunities for rideshare are emerging, especially for scientific payloads. The NASA Launch Services Program runs the Educational Launch of Nanosatellites (ELaNa) program under the CubeSat Launch Initiative (CSLI), run by the NASA Launch Services Program. CSLI provides competitive opportunities for CubeSats to launch to the ISS, or as secondary payloads with other missions through the ELaNa program at no cost to the CubeSat project. Pending the completion of the Space Launch System (SLS), there will also be opportunities for beyond LEO CubeSat launches.34 On February 2, 2016, NASA announced that 13 science and technology CubeSats would be carried on the first flight of the SLS launch, along with the SLS Orion crew vehicle on a mission called EM-1.
Outside the government, the U.S. launch provider United Launch Alliance (ULA) recently announced a program to provide competitive free rides on future launches for university-based CubeSats.35 Companies like Spaceflight Industries, Tyvak Nanosatellite Systems, and Nanoracks in the United States, while they do not provide
31 E. Nightingale, L. Pratt, and A. Balakrishnan, 2015, The CubeSat ecosystem: Examining the launch niche, Proceedings of 66th International Astronautical Congress, IAC-15,B4,5,3,x31157, October 12-16 2015, Jerusalem, Israel, available at https://www.ida.org/idamedia/Corporate/Files/Publications/STPIPubs/2016/D-5678.ashx.
32 E. Buchen, 2015, “Small Satellite Market Observations,” Proceedings of the AIAA/USU Conference on Small Satellites, SSC15-VII-7, http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3215&context=smallsat.
33 C. Niederstrasser and W. Frick, 2015, “Small Launch Vehicles—A 2015 State of the Industry Survey,” Proceedings of the AIAA/USU Conference on Small Satellites, Technical Session II: Launch, SSC15-II-7, http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3176&context=smallsat.
34 For the moment, this opportunity is for NASA only. However, it is important to note because it shows interest by NASA in furthering the use of CubeSats beyond Earth orbit. E. Nightingale, L. Pratt, and A. Balakrishnan, 2015, The CubeSat ecosystem: Examining the launch niche, Proceedings of 66th International Astronautical Congress, IAC-15,B4,5,3,x31157, October 12-16 2015, Jerusalem, Israel, available at https://www.ida.org/idamedia/Corporate/Files/Publications/STPIPubs/2016/D-5678.ashx.
35 United Launch Alliance, “United Launch Alliance Reveals Transformational CubeSat Launch Program,” release date November 19, 2015, http://www.ulalaunch.com/ula-reveals-transformational-cubesat-launch.aspx.
launch, act as a “one stop shop” or broker for launch coordination and integration.36 Several launch vehicles for small satellites (including 4 that focus on CubeSats)—more than 20 according to recent compilations—are under development.37 However, as was shown in the recent failure of the Super Strypi vehicle,38 there is no guarantee that these firms will survive technological and financial challenges and be able to provide the services, especially to the scientific community.
Despite the opportunities, there is a pent-up demand for affordable launch. The NASA CSLI has a waiting list of 62 CubeSats awaiting launch while 43 of 105 selections have launched as of 2015.39 The new Venture Class Launch Services (VCLS) program under CSLI is reducing the backlog via manifest of CubeSats on dedicated launch vehicles such as those offered by FireFly Space Systems, Rocket Labs, and Virgin Galactic. If CubeSats grow in number and utility as expected, low-cost launch availability will need to increase.
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
36 There are international brokers as well. Two known ones are “The Group of Astrodynamics for the Use of Space Systems” and “Adaptive Launch Solution.”
37 E. Nightingale, L. Pratt, and A. Balakrishnan, 2015, The CubeSat ecosystem: Examining the launch niche, Proceedings of 66th International Astronautical Congress, IAC-15,B4,5,3,x31157, October 12-16 2015, Jerusalem, Israel, available at https://www.ida.org/idamedia/Corporate/Files/Publications/STPIPubs/2016/D-5678.ashx.
38 NASA Spaceflight.com, “Super Strypi conducts inaugural launch—Fails during first stage,” release date November 3, 2015, http://www.nasaspaceflight.com/2015/11/super-strypi-spark-inaugural-launch/.
39 NASA, “CubeSat Launch Initiative Selectees,” release date February 28, 2013, https://www.nasa.gov/directorates/heo/home/CSLI_selections.html#.VwfZF_krJhF.
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.
The CubeSats community is directly affected by rules of the International Traffic in Arms Regulations (ITAR) that control the export and import of defense-related articles and services on the U.S. Munitions List (USML). Whereas ITAR is often mentioned as a major hurdle for international science collaborations and also competitiveness, the issues are very difficult to assess at this time. It is too early to see the impact of recent (2014) changes in the ITAR regime on the academic and educational CubeSat community. However, university representatives still find them complicated, are concerned that students are missing opportunities to be exposed to the latest technologies, and believe that the compliance burden could hinder science, invention, business, and innovation, especially between international partners or when including graduate students who are not U.S. born.
Planetary protection is another policy concern related to CubeSats for deep space or planetary science missions. Planetary protection, a part of NASA exploration since the Apollo Era, deals with the practice of protecting solar system bodies from Earth contaminants (forward contamination) as well as protecting Earth from extraterrestrial contaminants that might be returned within the solar system (backward contamination). It is essential that spacecraft are not responsible for depositing or returning contaminants that would obscure the ability to conclusively determine the existence of life elsewhere in addition to the need to protect Earth’s biome. NASA directives define policy and procedures associated with inbound and outbound spacecraft, and at this current time, CubeSats need to adhere to the requirements as specified for existing spacecraft systems. For the time being, for CubeSats, this includes trajectory analysis to ensure that systems will not impact other solar system bodies and requirements for spacecraft cleanliness that are dependent on type of mission, such as a flyby, orbiter, or lander, as well as the target body such as a planet, moon, comet, or asteroid. JPL’s MarCO flyby mission to Mars has procedural requirements that must be met for planetary protection.