A new era of small satellites has emerged augmenting larger systems and, in some cases, replacing them. Governments are taking a new look at small satellites, as commercial customers use them for their flexibility, speed of development, resiliency, low cost, and tolerance of risk in cutting edge technology. New constellations of 1000-plus satellites are being proposed. Advances in micro-electronics have enabled small spacecraft to maintain performance characteristics of modern spacecraft in unbelievably small packages. These spacecraft are inexpensive to build, test, and launch – which has enabled the production of large constellations. These constellations are being used to provide daily imagery enabling new uses in defence, agriculture, business intelligence, forestry, and disaster recovery. Small satellites will be the next space race. Important to understand what constitutes small satellites, their advantages and where is India.
What are Small Satellites?
A small satellite, miniaturized satellite, or small sat is a satellite of low mass and size, usually under 500 kg (1,100 lb.). While all such satellites can be referred to as “small”, different classifications are used to categorize them based on mass. Satellites can be built small to reduce the large economic cost of launch vehicles and the costs associated with construction. Miniature satellites, especially in large numbers, may be more useful than fewer, larger ones for some purposes – for example, gathering of scientific data and radio relay. Technical challenges in the construction of small satellites may include the lack of sufficient power storage or of room for a propulsion system.
|Satellite Type||Mass (Kg)|
|Large satellite||Over 1,000|
|Medium satellite||500 to 1,000|
|Mini satellite||100 to 500|
|Micro satellite||10 to 100|
|Nano satellite||1 to 10|
|Pico satellite||0.1 to 1|
Why Small Satellites?
One rationale for miniaturizing satellites is to reduce the cost; heavier satellites require larger rockets with greater thrust that also have greater cost to finance. In contrast, smaller and lighter satellites require smaller and cheaper launch vehicles and can sometimes be launched in multiples. They can also be launched ‘piggyback’, using excess capacity on larger launch vehicles. Miniaturized satellites allow for cheaper designs and ease of mass production. Another major reason for developing small satellites is the opportunity to enable missions that a larger satellite could not accomplish, such as: constellations for low data rate communications; using formations to gather data from multiple points; in-orbit inspection of larger satellites; university-related research; testing or qualifying new hardware before using it on a more expensive spacecraft. Small satellite examples include Demeter, Essaim, Parasol, Picard, MICROSCOPE, TARANIS, ELISA, SSOT, SMART-1, Spirale-A and -B, and Starlink satellites.
The nanosatellite and microsatellite segments of the satellite launch industry have been growing rapidly in recent years. Development activity in the 1–50 kg range has been significantly exceeding that in the 50–100 kg range. In the 1–50 kg range, fewer than 15 satellites were launched annually in 2000 to 2005. This rose to 34 launched in 2012 and 92 launched in 2013. European analyst Euroconsult projects more than 500 smallsats being launched in 2015–2019 with a market value estimated at US$7.4 billion. By mid-2015, many more launch options had become available for smallsats, and rides as secondary payloads had become both greater in quantity and easier to schedule on shorter notice.
As per Analysis by Maxime Puteaux and Alexandre Najjar, for Space News, in a study titled “Are smallsats entering the maturity stage?” In 2018, 322 small satellites were launched globally through 44 launches. For the second year in a row, the number of smallsats launched was above the 300 units-per-year threshold, i.e. twice more than the 160-per-year average identified between 2013 and 2017. Smallsats accounted for 69% of the satellites launched last year in number of satellites but only 4% of the total mass launched (i.e. 372 tons). Last year, 50% of the demand was driven by the U.S., with more than 100 of those smallsats belonging to commercial companies. Technology demonstration was the main application.
Small satellite launch vehicle
Although smallsats have traditionally been launched as secondary payloads on larger launch vehicles, a number of companies currently are developing or have developed launch vehicles specifically targeted at the smallsat market. In particular, the secondary payload paradigm does not provide the specificity required for many small satellites that have unique orbital and launch-timing requirements. Companies offering smallsat launch vehicles include, Rocket Lab’s Electron (225 kg), Virgin Orbit’s LauncherOne (500 kg), and Astra’s Rocket 3.0 (100 kg).
The term “microsatellite” or “microsat” is usually applied to the name of an artificial satellite with a wet mass between 10 and 100 kg. However, this is not an official convention and sometimes those terms can refer to satellites larger than that, or smaller than that (e.g., 1–50 kg (2.2–110.2 lb.)). Sometimes, designs or proposed designs from some satellites of these types have microsatellites working together or in a formation. The generic term “small satellite” or “smallsat” is also sometimes used, as is “satlet”. Astrid-1 and Astrid-2, are small satellites. In 2018, the two Mars Cube One microsats—massing just 13.5 kg each—became the first CubeSats to leave Earth orbit for use in interplanetary space. They flew on their way to Mars alongside the successful Mars Insight lander mission. The two microsats accomplished a flyby of Mars in November 2018, and both continued communicating with ground stations on Earth through late December. Both went silent by early January 2019.
Microsatellite launch vehicle
A number of commercial and military-contractor companies are currently developing microsatellite launch vehicles to perform the increasingly targeted launch requirements of microsatellites. While microsatellites have been carried to space for many years as secondary payloads aboard larger launchers, the secondary payload paradigm does not provide the specificity required for many increasingly sophisticated small satellites that have unique orbital and launch-timing requirements. In July 2012, Virgin Galactic announced LauncherOne, an orbital launch vehicle designed to launch “smallsat” primary payloads of 100 kg into low-Earth orbit, with launches projected to begin in 2016. Several commercial customers have already contracted for launches, including GeoOptics, Skybox Imaging, Spaceflight Industries, and Planetary Resources. Both Surrey Satellite Technology and Sierra Nevada Space Systems are developing satellite buses “optimized to the design of LauncherOne”. Virgin Galactic has been working on the LauncherOne concept since late 2008, and as of 2015, was making it a larger part of Virgin’s core business plan as the Virgin human spaceflight program has experienced multiple delays and a fatal accident in 2014.
In December 2012, DARPA announced that the Airborne Launch Assist Space Access program would provide the microsatellite rocket booster for the DARPA SeeMe program that intended to release a “constellation of 24 micro-satellites (~20 kg (44 lb.) range) each with 1-m imaging resolution.” The program was cancelled in December 2015. In April 2013, Garvey Spacecraft was awarded a US$200,000 contract to evolve their Prospector 18 suborbital launch vehicle technology into an orbital nanosat launch vehicle capable of delivering a 10 kg payload into a 250 km orbit to an even-more-capable clustered “20/450 Nano/Micro Satellite Launch Vehicle” (NMSLV) capable of delivering 20 kg payloads into 450 km (280 mi) circular orbits.
The Boeing Small Launch Vehicle is an air-launched three-stage-to-orbit launch vehicle concept aimed to launch small payloads of 45 kg (100 lb.) into low-Earth orbit. The program is proposed to drive down launch costs for U.S. military small satellites to as low as US$300,000 per launch ($7,000/kg) and, if the development program was funded, as of 2012 could be operational by 2020. The Swiss company Swiss Space Systems (S3) has announced plans in 2013 to develop a suborbital spaceplane named SOAR that would launch a microsat launch vehicle capable of putting a payload of up to 250 kg into low-Earth orbit. The Spanish company PLD Space formed in 2011 with the objective of developing low cost launch vehicles called Miura 1 and Miura 5 with the capacity to place up to 150 kg into orbit.
Nanosatellites – Satellite Swarm
The term “nanosatellite” or “nanosat” is applied to an artificial satellite with a wet mass between 1 and 10 kg. Designs and proposed designs of these types may be launched individually, or they may have multiple nanosatellites working together or in formation, in which case, sometimes the term “satellite swarm” or “fractionated spacecraft” may be applied. Some designs require a larger “mother” satellite for communication with ground controllers or for launching and docking with nanosatellites. Over 1300 nanosatellites have been launched as of January 2020.
With continued advances in the miniaturization and capability increase of electronic technology and the use of satellite constellations, nanosatellites are increasingly capable of performing commercial missions that previously required microsatellites. For example, a 6U CubeSat standard has been proposed to enable a constellation of 35, 8 kg Earth-imaging satellites to replace a constellation of five 156 kg RapidEye Earth-imaging satellites, at the same mission cost, with significantly increased revisit times: every area of the globe can be imaged every 3.5 hours rather than the once per 24 hours with the RapidEye constellation. More rapid revisit times are a significant improvement for nations performing disaster response, which was the purpose of the RapidEye constellation. Additionally, the nanosat option would allow more nations to own their own satellite for off-peak (non-disaster) imaging data collection. As costs lower and production times shorten, nanosatellites are becoming increasingly feasible ventures for companies. Some nanosatellites are ExoCube (CP-10), ArduSat, and SPROUT.
In the ten years of nanosat launches prior to 2014, only 75 nanosats were launched. Launch rates picked up substantially when in the three-month period from November 2013–January 2014 94 nanosats were launched. One challenge of using nanosats has been the economic delivery of such small satellites to anywhere beyond low-Earth orbit. By late 2014, proposals were being developed for larger spacecraft specifically designed to deliver swarms of nanosats to trajectories that are beyond Earth orbit for applications such as exploring distant asteroids. On 15 February 2017 India’s ISRO created a new world record for the largest number of satellites ever launched on a single rocket (104), surpassing the previous record of Russia, which in 2014 launched 37 satellites using Dnepr rocket. The PSLV-C37 rocket launched Cartosat-2D and 103 nanosatellites: two from India, one each from Kazakhstan, Israel, the Netherlands, Switzerland, and the United Arab Emirates, along with 96 from the United States of America (88 Dove satellites and 8 LEMUR satellites). The three Indian satellites launched were Cartosat-2D, INS-1A, and INS-1B.
Nanosatellite launch vehicle
With the emergence of the technological advances of miniaturization and increased capital to support private spaceflight initiatives in the 2010s, several startups have been formed to pursue opportunities with developing a variety of small-payload Nanosatellite Launch Vehicle (NLV) technologies. The NLVs proposed or under development include, Virgin Orbit LauncherOne upper stage, intended to be air-launched from WhiteKnightTwo similar to how the SpaceShipTwo spaceplane is launched. Ventions’ Nanosat upper stage. Nammo/Andøya North Star (polar orbit-capable launcher for a 10 kg (22 lb.) payload). Garvey Spacecraft (now Vector Launch) is evolving their Prospector 18 suborbital launch vehicle technology into an orbital nanosat launch vehicle capable of delivering a 10 kg payload into a 250 km orbit. Generation Orbit is developing an air-launched rocket to deliver both nanosats and sub-50 kg microsats to low Earth orbit. NASA launched three satellites on 21 April 2013 based on smart phones. Two phones use the PhoneSat 1.0 specification and the third used a beta version of PhoneSat 2.0. ISRO launched 14 nanosatellites on 22 June 2016, 2 for Indian universities and 12 for the United States under the Flock-2P program. This launch was performed during the PSLV-C34 mission.
ISRO Small Satellites
The Indian Mini Satellite -1 (IMS-1) bus has been developed as a versatile bus of 100 kg class which includes a payload capability of around 30 kg. The bus has been developed using various miniaturization techniques. The first mission of the IMS-1 series was launched successfully on April 28th 2008 as a co-passenger along with Cartosat 2A. Youthsat is second mission in this series and was launched successfully along with Resourcesat 2 on 20th April 2011. Indian Mini Satellite -2 (IMS-2) Bus is evolved as a standard bus of 400 kg class which includes a payload capability of around 200kg. IMS-2 development is an important milestone as it is envisaged to be a work horse for different types of remote sensing applications. The first mission of IMS-2 is SARAL. SARAL is a co-operative mission between ISRO and CNES with payloads from CNES and spacecraft bus from ISRO.
The term “picosatellite” or “picosat” (not to be confused with the PicoSAT series of microsatellites) is usually applied to artificial satellites with a wet mass between 0.1 and 1 kg, although it is sometimes used to refer to any satellite that is under 1 kg in launch mass. Again, designs and proposed designs of these types usually have multiple picosatellites working together or in formation (sometimes the term “swarm” is applied). Some designs require a larger “mother” satellite for communication with ground controllers or for launching and docking with picosatellites. Picosatellites are emerging as a new alternative for do-it-yourself kitbuilders. Picosatellites are currently commercially available across the full range of 0.1–1 kg. Launch opportunities are now available for $12,000 to $18,000 for sub-1 kg picosat payloads that are approximately the size of a soda can.
The term “femtosatellite” or “femtosat” is usually applied to artificial satellites with a wet mass below 100 g. Like picosatellites, some designs require a larger “mother” satellite for communication with ground controllers. Three prototype “chip satellites” were launched to the ISS on Space Shuttle Endeavour on its final mission in May 2011. They were attached to the ISS external platform Materials International Space Station Experiment (MISSE-8) for testing. In April 2014, the nanosatellite KickSat was launched aboard a Falcon 9 rocket with the intention of releasing 104 femtosatellite-sized chipsats, or “Sprites”. In the event, they were unable to complete the deployment on time due to a failure of an onboard clock and the deployment mechanism reentered the atmosphere on 14 May 2014, without having deployed any of the 5-gram femtosats. ThumbSat is another project intending to launch femtosatellites in the late 2010s. ThumbSat announced a launch agreement with CubeCat in 2017 to launch up to 1000 of the very small satellites. In March 2019, the CubeSat KickSat-2 deployed 105 femtosats called “ChipSats” into Earth orbit. The satellites were tested for 3 days, and they then reentered the atmosphere and burned up.
Indian Private Technology Stratups
Many emerging private technology startups provide opportunities for the Indian armed services to leverage Small Sats. Bellatrix Aerospace, Dhruva Space, Kawa Space, AgniKul Cosmos and Astrogate Labs are some of the major Indian space startups. They work range from electro-optical and communications satellite systems to launch vehicle technology. Indian military leadership, government directives and authorisation, should encourage these space startups. Indian space technology unicorns will contribute to the development of their own SSLVs, thereby bringing down launch costs.
Small satellites usually require innovative propulsion, attitude control, and communication and computation systems. Larger satellites usually use monopropellants or bipropellant combustion systems for propulsion and attitude control; these systems are complex and require a minimal amount of volume to surface area to dissipate heat. These systems may be used on larger small satellites, while other micro/nanosats have to use electric propulsion, compressed gas, vaporizable liquids such as butane or carbon dioxide or other innovative propulsion systems that are simple, cheap and scalable.
Small satellites can use conventional radio systems in UHF, VHF, S-band and X-band, although often miniaturized using more up-to-date technology as compared to larger satellites. Tiny satellites such as nanosats and small microsats may lack the power supply or mass for large conventional radio transponders, and various miniaturized or innovative communications systems have been proposed, such as laser receivers, antenna arrays and satellite-to-satellite communication networks. Few of these have been demonstrated in practice.
Electronics need to be rigorously tested and modified to be “space hardened” or resistant to the outer space environment (vacuum, microgravity, thermal extremes, and radiation exposure). Miniaturized satellites allow for the opportunity to test new hardware with reduced expense in testing. Furthermore, since the overall cost risk in the mission is much lower, more up-to-date but less space-proven technology can be incorporated into micro and nanosats than can be used in much larger, more expensive missions with less appetite for risk.
There are thousands of pieces of orbital debris (fragments of old satellites, old rocket bodies, or similar non-active objects). The estimated population of particles between 1 and 10 cm in diameter is approximately 500,000. The number of particles smaller than 1 cm exceeds 100 million. Orbital debris are all man-made objects in orbit about the Earth which no longer serve a useful purpose. These cannot be maneuvered out of the way of a collision. Most operational satellites can and do change their orbit periodically. Typically this is done to counteract the effects of atmospheric drag, thereby meeting their altitude or ground track requirements. Sometimes, they will maneuver to avoid a close approach with either Orbital Debris or with another satellite. This type of maneuver is called a risk mitigation maneuver (RMM). Small satellites are difficult to track with ground-based radar, so it is difficult to predict if they will collide with other satellites or human-occupied spacecraft. The U.S. Federal Communications Commission has rejected at least one small satellite launch request on these safety grounds.
Defence Applications Small Satellites
The rising spacecraft density in LEO makes the deployment of large constellations risky. Nevertheless, they need to be operationally pursued. The small Satellite constellation for military applications must be launched in clusters. The armed services can use secure civil constellations for communications or remote sensing requirements. The US Iridium, Small Sat constellation in LEO provides mobile satellite service for voice and data coverage globally. The SkyGlobal, is a constellation of 60 satellites in LEO that provides imagery over North America, North China and Europe every 18 minutes. India should also pursue a limited area Small Sat constellation, with a capacity to perform a range of missions and tasks. The design of a Small Sat network should cover most areas of military operation. Small Sat could meet the military’s C4ISR requirements. Establishment of a Defence Innovation Unit will help facilitate interaction between the armed services and space technology startups. Indian space startups such as Bellatrix Aerospace, Dhruva and Kawa space are making space technology more affordable.
The Small Sat revolution is widely considered consequential for communications, imagery, reconnaissance and surveillance. Main focus being the C4ISR-related military applications. Their development cycles are shorter and offer “responsive capability” for military contingencies. A Small Sat constellation can be rapidly launched using a Small Satellite Launch Vehicle (SSLV) provides a measure of survivability by way of “surge” capacity, which generates a proliferation of space assets against the adversary’s anti-satellite capabilities.
Small Sats provide redundancy in terms of numbers and capabilities. They also provide flexibility by allowing military planners and decision-makers to switch to sensors from which to service their C4ISR needs. Ka-Band can be complemented with the X-band frequency payloads, which is generally used for high throughput missions by militaries across the world. They also add survivability needed in war by creating larger number of targets for the adversary to strike and destroy. Small Sats are easily replaceable at the end of their natural life or if destroyed as a result of military action from KEWs, DEWs, and cyber and electronic attacks. Small Sats provide greater in-orbit mobility and are not easy to destroy. The US Navy is also developing nanosatellites for ultra-high frequency communications and the USAF is developing ground infrastructure to sustain Small Sat deployment. USAF is using cloud computing and data processing innovations from commercial space to manage Small Sat constellations in LEO.
Chinese Small Sat Capability
China is already a far more formidable space military player. China already has a constellation of satellites as part of the Yaogan series, which is a network of electro-optical, imagery intelligence (IMINT), synthetic aperture radar (SAR) satellites and electronic intelligence satellites (ELINT). The Yaogan satellites operate within a 2000-km altitude, making them LEO-based spacecraft. They are not Small Sats. The Yaogan 9 satellites, could be able to pinpoint, visualise and direct missile attacks against fixed Indian targets, such as air bases and advanced landing grounds. The Yaogan satellites are significant to the Chinese military’s ability to maintain constant surveillance and track naval movements across the South China Sea, Western Pacific and Indian Ocean. A significant number of space startups in China are planned as LEO satellite constellations, providing remote sensing and communications to meet the C4ISR needs of the Chinese military. It is important to recognise that satellites launched ostensibly for civilian or commercial purposes can carry military payloads as well. Although the US launched the greatest number of Small Sats between 2014 and 2019, China launched Small Sats mainly with military and industrial applications.
Small Sats and Indian Armed Forces
Small Sats will be crucial for Indian Armed forces, both as sensors and for networked operations. High satellite revisit rates and continuous surveillance, reconnaissance and communications are key. The requirement will be significant initially for air and maritime operations. Subsequently Indian Army must leverage space borne sensors and imagery for its war-fighting needs. The PLAAF considers air and space operations to be inseparable and central to the conduct of modern air warfare. Similarly the IAF’s doctrine considers space assets for air warfare and uses the unitary phrase “aerospace”. The mountainous border with China puts limitations on ground based sensors. UAVs have limited range and coverage. The larger GSAT-7 series of satellites in wartime, are likely to be vulnerable and easy targets. The loss of large communications satellites will seriously impair military operations. The GSAT-7A greatly supports IAF’s AFNet and IACCS, but they can be greatly bolstered with the Small Sats, and add redundancy. LEO-based Small Sats can also help the IAF strengthen the networking and communications capacities of the AFNet and IACCS. Small Sats in due course will increasingly meet the communications requirements of the Predator type UAVs. The real test for the IA, IN and IAF is in developing and using Small Sats to deliver Ka-band and Ku-band communications, voice communications and jam-resistant relays from LEO. In addition to position, navigation and timing (PNT) and persistent ISR mission capabilities at the tactical level, LEO-based Small Sats will provide the armed services with greater battle-space awareness and enable more integrated operations. Even the Indian Regional Navigation Satellite System, or NavIC needs to be supplemented with Small Sats in LEO. The Indian armed services can avail the ISRO-developed three-staged SSLV for low cost and rapid launches. This SSLV is capable of carrying a 500-kg payload to LEO and a 300-kg to SSO. The wide swath of GEO satellites is inadequate for IMINT and ELINT related tasks. LEO constellations, on the other hand, can provide persistent ISR coverage.
Indian Navy’s maritime surveillance aircraft, P8-I Poseidon had to be deployed in Ladakh recently to augment ISR capability. This could have best been done by Small Sats. What the Indian armed services lack is an in-depth space architecture, and this must be articulated as part of the tri-service doctrine. Meanwhile China has a slew of capabilities, ranging from the kinetic to the non-kinetic, to destroy heavy communications satellites in Geo orbit. India has to thus build redundancy through Small Sats. The emergence and operationalisation of ISRO’s SSLV in the coming months will make the launch costs of 500-kg payloads to LEO significantly cheaper than the PSLV.
In coming years, constellations composed of large numbers of small, less complex, and less costly satellites are likely to become progressively more cost-effective relative to constellations made up of small numbers of large, more complex, and more expensive satellites. Movement in this direction, which is already clearly visible in commercial space, is the result of a variety of factors, including continued improvements in the miniaturization of computers, sensors, and other technologies and, even more importantly, reductions in space launch costs.
The exponential growth of the global market for small satellites with a launch mass below 500 kilograms over the last decade is due in part to a small initial market size. The smallsat market experienced a 23% compound annual growth rate (CAGR) from 2009 to 2018. Even greater expansion is expected between 2019 and 2024. There is still some uncertainty, and more stable pace of maintenance and replenishment is expected by 2025. In the fifth edition of “Prospects for the Small Satellite Market,” Euroconsult anticipates the rolling five-year growth rate for smallsats to peak at 48% in 2024. Following 2024, market size should stabilize until second-generation megaconstellations begin to launch. Euroconsult projects that between 2019 and 2028, more than 8,500 satellites will be launched, half of which will be to support broadband constellations, for a total market value of $42 billion.
Smallsat broadband megaconstellations are becoming a reality by entering full deployment after successful in-orbit validation. The most advanced projects, are OneWeb and SpaceX’s Starlink. Other projects outside of the smallsat range (i.e., Telesat, Leosat) are gearing up, too. Market segments other than broadband constellations include government (defence), Earth observation and narrowband providers. The most advanced optical Earth observation constellations are nearing the completion of their first generation. Other value propositions with different sensors are emerging, such as synthetic aperture radar and hyperspectral imaging. Companies sponsoring narrowband projects for Internet of Things applications have interest. Dedicated solutions such as micro launchers are just becoming available. On the manufacturing side, mass production of megaconstellation is just beginning to meet deadlines set by spectrum licensing authorities. Enabling components such as electric propulsion and deployable antennas to be tested before commercialization will provide more agility to their customers.
During the upcoming years, the market will drive the value of propositions currently under development and determine whether smallsats are now reaching a new threshold of maturity or if radical and quick changes are now part of the whole satellite industry.
Header Image Source: space.com
- Small Satellites Wikipedia https://en.wikipedia.org/wiki/Small_satellite
- Small Satellites ISRO https://www.isro.gov.in/spacecraft/small-satellites
- Small Satellites NASA https://www.nasa.gov/mission_pages/smallsats
- The Bright Future of Small Satellites https://www.nlr.org/article/the-bright-future-of-small-satellites/
- Kartik Bommakanti, ORF, Strengthening the C4ISR capabilities of India’s Armed Forces: The Role of Small Satellites www.orfonline.org/research/strengthening-the-c4isr-capabilities-of-indias-armed-forces-the-role-of-small-satellites-67842/