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 over a thousand 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 (SmallSats) will be the next space race. It is important to understand what constitutes small satellites, their advantages and where does India stand in this?
What are Small Satellites?
A small satellite, miniaturised satellite or small sat is a satellite of low mass and size, usually under 500kg. While all such satellites can be referred to as ‘small’, different classifications are used to categorise 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 Classification by Weight
Mass Classifications Defined by FAA
|Satellite Type||Mass (kg)|
|Nano||1 to 10|
|Pico||0.1 to 1|
Why Small Satellites?
One rationale for miniaturising 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. Miniaturised 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. Many Start Ups have come into the small satellite space. Start up space ventures brought in a record $15 billion in financing in 2021. Activity is happening all around the globe as established space powers continue to progress and other countries invest in their space capabilities. Some of the top global small satellite start-ups include Gilmour Space of Australia, Impulse Space Propulsion, Innova Space and Mission Space among others.
Recent SmallSats Statistics
The nano-satellite and microsatellite segments of the satellite launch industry have been growing rapidly in recent years. Development activity in the 1kg to 50kg range has been significantly exceeding that in the 50kg to 100kg range. 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 Bryce Tech, 94 percent of space craft launched in 2021 were for SmallSats. 43 per cent of total up-mass was SmallSats and 69 per cent of all SmallSats launched in the last ten years were in 2020-2021. Six percent of SmallSats were launched on small/micro launch vehicles. In 2021, Starlink and OneWeb launched 1,273 SmallSats compared to 470 by all others. 82 percent of the SmallSats were in the Mini and Micro categories. 80 percent of the SmallSats launched in 2021, were for communications and nine per cent each for remote sensing and technology development. In 2021, 86 per cent of SmallSats were owned by five operators – SpaceX (1944), Planet (485), OneWeb (394), Spire Globe (147) and Swarm Technologies (121). 70 percent of the SmallSats were owned by the US, nine per cent by UK and six per cent by China. India had total of 21 and was at the 13th position by SmallSat numbers. India ranked five in pure government SmallSats.
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. In August 2022, ISRO launched its developmental Small Satellite Launch Vehicle SSLV-D1 to cater to the launch of small satellites up to 500kg to Low Earth Orbits on ‘launch-on-demand’ basis. In February 2023, SSLV D-2, configured with three solid stages and having a lift-off mass of 120 tonne, was launched to carry EOS-07, a 153.6 kg Earth Observation Satellite, Janus-1, a technology demonstration satellite weighing 10.2kg belonging to ANTARIS, USA and AzaadiSAT-2, an 8.8kg satellite realised by Space Kidz India. India will now commercialise the SSLVs through Industry on demand basis catering to the increasing Indian and global needs. There are many global and Indian private companies in the SmallSat launch space.
A CubeSat is a class of miniaturised satellite of around 10cm cubes and weighing less than 2kg and often use Commercial Off-The-Shelf (COTS) electronic components and structure. As of August 2021, more than 1,600 CubeSats have been launched. Typically, they have been used for technology development for SmallSats, earth observation or amateur radio. Their low cost can justify higher risks. Biological research payloads have also been flown. The first CubeSats in deep space were flown in the MarCO mission, where two CubeSats were launched towards Mars in May 2018, alongside the successful InSight mission.
Microsatellite Launch Vehicle
Many companies are developing dedicated microsatellite launch vehicles capable of delivering a 10kg payload into a 250km orbit or even-more-capable clustered 20/450 Nano/Micro Satellite Launch Vehicle (NMSLV) capable of delivering 20kg payloads into 450km circular orbits. The Boeing Small Launch Vehicle is an air-launched three-stage-to-orbit launch vehicle concept aimed to launch small payloads of 45kg into Low Earth Orbit. The programme is proposed to drive down launch costs for the US military small satellites to as low as $7,000/kg.
Nano Satellite and Satellite Swarm
Nano satellites may be launched individually or multiple in what they call a ‘satellite swarm’. Some designs require a larger “mother” satellite for communication with ground controllers or for launching and docking with nano satellites. As per nano satellite database published by European Union, as of January 2023, 2,138 Nanosats, 1,960 CubeSats and 15 Interplanetary CubeSats have been launched by 80 countries. There are 638 companies in the field and over 2,080 additional Nanosats are expected to be launched in next six years. With continued advances in the miniaturisation and capability increase of electronic technology and the use of satellite constellations, nano satellites 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, 8kg earth-imaging satellites to replace a constellation of five 156kg 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 in 24 hours with the RapidEye constellation. More rapid revisit times are required for nations performing disaster response. The nanosats also allow more nations to own their own satellite as lower costs and shorter production times.
As on date, over 1,000 nanosats are in constellations. Countries are working on larger spacecraft specifically designed to deliver swarms of nanosats to trajectories that are beyond the 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) launched on the PSLV-C37 rocket. Several start-ups have been working to develop Nanosatellite Launch Vehicles (NLV).
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 30kg. The bus has been developed using various miniaturisation techniques. The first mission of the IMS-1 series was launched successfully on 28 April 2008, as a co-passenger along with Cartosat 2A. Youthsat was the second mission in this series and was launched successfully along with Resourcesat 2 on 20 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 (SARAL) was a co-operative mission between ISRO and CNES with payloads from CNES and spacecraft bus from ISRO. PSLV-C37 carried two ISRO Nanosatellites – the INS-1A and INS-1B as co-passenger satellites, which was launched on February 15, 2017. INS-1C was launched by PSLV-C40 on January 12, 2018, as a co-passenger satellite.
Multiple pico-satellites are also expected to work together in a swarm. Some designs require a larger ‘mother’ satellite for communication with ground controllers or for launching and docking with pico-satellites. Pico-satellites are emerging as a new alternative for ‘do-it-yourself’ kit builders. Pico-satellites are currently commercially available across the full range of 0.1–1kg. Launch opportunities are now available for $12,000 to $18,000 for sub-1kg pico-sat payloads that are approximately the size of a soda can.
Like pico-satellites, they too may require a larger ‘mother’ satellite for communication with ground controllers. These satellites, when launched in large numbers, are useful for gathering of scientific data as well as for radio relay. 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 five-gramme femto-satellite-sized chipsats or ‘Sprites’. They were, however, unable to complete the deployment for technical reasons.
In March 2019, the CubeSat KickSat-2 deployed 105 femto sats called ‘ChipSats’ into earth orbit. The satellites were tested for three days, and they then re-entered the atmosphere and burned up. A hundred femto satellites, made of composite material, measuring 4cmx4cmx4cm, designed and developed by 1,000 students from across the country, were launched in February 2021 via a high altitude scientific balloon. The satellites were equipped with sensors to study areas like ozone, cosmic ray, carbon dioxide and humidity.
Indian Private Technology Start-ups
Many emerging private technology start-ups provide opportunities for the Indian armed forces to leverage SmallSats. The five Indian Start-ups to watch in 2023 are – Skyroot Aerospace, Pixxel, Agnikul Cosmos, Dhruva Space and Bellatrix Aerospace. There are many other players in this domain. Their work ranges from electro-optical and communications satellite systems to launch vehicle technology. Indian military leadership, government directives and authorisation have begun encouraging these space start-ups. Indian space technology unicorns will contribute to the development of their own SSLVs, thereby bringing down launch costs.
Technical Challenges for SmallSats
Small satellites usually require innovative propulsion, attitude control as well as communication and computation systems. Larger satellites usually use mono-propellants or bi-propellant 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/nano-sats have to use electric propulsion, compressed gas, vaporisable 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 miniaturised 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 miniaturised 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). Miniaturised 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.
Orbital debris could be as small as tiny flecks of paint or bits of metal that have come off spacecraft. Large debris could be an entire satellite that is no longer working or upper stages of rockets that could even contain fuel or high-pressure fluids. Orbital debris larger than one centimetre can be dangerous. The ‘space junk’ is moving at seven to eight kilometres per second or 28,000 kmph. That speed is almost seven times faster than a bullet. If moving towards each other, the closure speed would be much higher. At those speeds even a tiny piece of debris can cause a lot of damage. As per NASA, about 13,000 known objects in space are bigger than ten centimetres in diameter. The estimated population of particles between one centimetre and ten centimetres in diameter is approximately 500,000. The number of particles smaller than one cm exceeds 100 million. All space shuttles have returned with many dent marks. This man-made debris cannot be manoeuvered out of the way of a collision. Most operational satellites can and do change their orbits periodically. Typically, this is done to counteract the effects of atmospheric drag, thereby meeting their altitude or ground track requirements. Sometimes, they will manoeuvre to avoid a close approach with either Orbital Debris or with another satellite. This type of manoeuvre is called a Risk Mitigation Manoeuvre (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.
Defence Applications Small Satellites
The SmallSats revolution is widely considered consequential for communications, imagery, reconnaissance and surveillance. The rising spacecraft density in LEO makes the deployment of large constellations risky. Nevertheless, they need to be operationally pursued. The SmallSat constellation for military applications must be launched in clusters. The armed forces can use secure civil constellations for communications or remote sensing requirements. Over 90 percent of the constellations are in LEO. US SmallSats constellations such as Spire (Lemur) have 160 satellites and Iridium (NEXT) with 75 SmallSats in LEO provide mobile satellite service for voice and data coverage globally. A hyper-spectral SmallSats constellation of 600 is planned. SpaceXStarlink has already launched 3,500 SmallSats for broadband internet constellations. The major countries, including India, have satellite navigation constellations of relatively larger satellites.
India is also pursuing limited area SmallSats constellation, with a capacity to perform a range of missions and tasks. The design of a SmallSat network should cover most areas of military operation. SmallSats could meet the military’s C4ISR requirements. A Defence Innovation Unit will help facilitate interaction between the armed services and space technology start-ups. Indian space start-ups are making space technology more affordable. SmallSat development cycles are shorter and offer ‘responsive capability’ for military contingencies. A SmallSat constellation can be rapidly launched using a Small Satellite Launch Vehicle (SSLV). It provides a measure of survivability by way of ‘surge’ capacity, which generates a proliferation of space assets against the adversary’s anti-satellite capabilities.
SmallSats 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. SmallSats are more easily replaceable at the end of their natural life or if destroyed as a result of military action from kinetic or directed energy weapons or disabled by cyber and electronic attacks. SmallSats 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 SmallSat deployment.
Chinese SmallSat 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 (ELINT) satellites. The Yaogan satellites operate within a 2,000-km altitude, making them LEO-based spacecraft. They are not SmallSats. The Yaogan 9 satellites could be able to pin-point, 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, the Western Pacific and the Indian Ocean.
A significant number of space start-ups 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 has launched the greatest number of SmallSats, China has been launching SmallSats mainly with military and industrial applications. Two new Chinese factories capable of producing hundreds of SmallSats per year could help China achieve space objectives and impact the international market. China Academy of Space Technology (CAST) plant at Tianjin, will produce more than 200 satellites per year. The China Aerospace Science and Industry Corporation (CASIC), completed its own factory in Wuhan in 2021, that is capable of manufacturing 240 small satellites each year.
SmallSats and the Indian Armed Forces
SmallSats are crucial for the Indian Armed Forces, both as sensors and for networked operations. High satellite revisit rates and continuous surveillance, reconnaissance and communications are the key. The requirements are significant initially for air and maritime operations. The Indian Army also 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 the IAF’s AFNet and the IACCS, but they can be greatly bolstered with the SmallSats and add redundancy. LEO-based SmallSats can also help the IAF strengthen the networking and communications capacities of the AFNet and IACCS. SmallSats will increasingly meet the communications requirements of the UAVs. The real test for the IA, IN and the IAF is in developing and using SmallSats to deliver Ka-band and Ku-band communications, voice communications and jam-resistant relays from LEO. In addition to Position, Navigation and Timing (PNT) as well as persistent ISR mission capabilities at the tactical level, LEO-based SmallSats will also provide the armed forces with greater battle-space awareness and enable more integrated operations. Even the Indian Regional Navigation Satellite System or NavIC needs to be supplemented with SmallSats in LEO. The Indian armed forces 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.
SmallSats would have augmented ISR capability during incidents like confrontation with China in Galwan in Ladakh. What the Indian armed forces 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 SmallSats.
The Way Ahead
In the 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 miniaturisation of computers, sensors and other technologies and even more importantly, reduction in space launch costs.
The exponential growth of the global market for SmallSats with a launch mass below 500kg over the last decade is indicative of the global trends. The SmallSat market experienced a 23 percent Compound Annual Growth Rate (CAGR) from 2009 to 2018. The SmallSat market was worth $3.2 billion in 2020 and is expected to reach $13.8 billion by 2030. A stable pace of maintenance and replenishment is expected by 2025. In the eighth edition of “Prospects for the Small Satellite Market,” Euroconsult anticipates the rolling five-year growth rate for SmallSats to peak at 48 percent in 2024. Following 2024, market size should stabilise until second-generation mega-constellations begin to launch. In Euroconsult projects between 2019 and 2028, more than 8,500 satellites will be launched, half of which will be to support broadband constellations.
On the manufacturing side, mass production of mega-constellation has begun meeting deadlines set by spectrum licensing authorities. Enabling components such as electric propulsion and deployable antennas to be tested before commercialisation will provide more agility to their customers. Time for India to launch big in numbers is now lest it gets left behind.