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Small satellites, or smallsats, are satellites of low mass and size, usually under 500 kg (1,100 lb). While all such satellites can be referred to as small satellites, different classifications are used to categorize them based on mass.
- 1 Rationales
- 2 History
- 3 Classification groups
- 4 Technical challenges
- 5 See also
- 6 References
- 7 External links
|Group name||Mass (kg)|
|Medium satellite||500 to 1000|
|Mini satellite||100 to 500|
|Micro satellite||10 to 100|
|Nano satellite||1 to 10|
|Pico satellite||0.1 to 1|
One rationale for miniaturizing satellites is to reduce the cost: heavier satellites require larger rockets with greater thrust that also has 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 as well as ease of mass production, although few satellites of any size other than 'communications constellations', where dozens of satellites are used to cover the globe, have been mass-produced in practice.
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
The nanosatellite and microsatellite segments of the satellite launch industry have been growing rapidly in recent years, and was based on the Spanish low cost manufacturing for Commercial and Communication Satellites from the 1990s. Development activity in the 1–50 kg (2.2–110.2 lb) range has been significantly exceeding that in the 50–100 kg (110–220 lb) range.
In the 1–50 kg range alone, there were fewer than 15 satellites launched annually in 2000 to 2005, 34 in 2006, then fewer than 30 launches annually during 2007 to 2011. This rose to 34 launched in 2012, and 92 launched in 2013.
European analyst Euroconsult projects more than 500 smallsats being launched in the years 2015–2019 with a market value estimated at US$7.4 billion.
The term "small satellite", or sometimes "minisatellite", often refers to an artificial satellite with a wet mass (including fuel) between 100 and 500 kg (220 and 1,100 lb), but in other usage has come to mean any satellite under 500 kg (1,100 lb).
Small satellite launch vehicle
Although smallsats have traditionally been launched as secondary payloads on larger launch vehicles, there are a number of companies currently developing 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 planning small sat launch vehicles include:
- Virgin Galactic's LauncherOne (100 kg)
- Firefly Space Systems' Alpha (400 kg).
- Rocket Lab's Electron (150 kg)
- PLD Space (150 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 (22 and 220 lb). 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".
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 (220 lb) into low-Earth orbit, with launches projected to begin in 2016. Several commercial customers have already contracted for launches, including GeoOptics, Skybox Imaging, Spaceflight Services, 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[update], is making it a larger part of Virgin's core business plan as the Virgin human spaceflight program has experienced multiple delays as well as 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 another DARPA program that is intending to release a "constellation of 24 micro-satellites (~20 kg (44 lb) range) each with 1-meter 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 (22 lb) payload into a 250 km (160 mi) orbit to an even-more-capable clustered "20/450 Nano/Micro Satellite Launch Vehicle" (NMSLV) capable of delivering 20 kg (44 lb) 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[update] 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 (550 lb) into low-Earth orbit.
The term "nanosatellite" or "nanosat" is applied to an artificial satellite with a wet mass between 1 and 10 kg (2.2 and 22.0 lb). 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.
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 (18 lb) Earth-imaging satellites to replace a constellation of five 156 kg (344 lb) 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.
Example satellites: ExoCube (CP-10)
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.
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.
NLVs proposed or under development include:
- Virgin Galactic 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)
- As of April 2013[update], Garvey Spacecraft is evolving their Prospector 18 suborbital launch vehicle technology into an orbital nanosat launch vehicle capable of delivering a 10 kg (22 lb) payload into a 250 km (160 mi) 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.
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 (0.22 and 2.2 lb), 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. The CubeSat design, with approximately 1 kilogram (2.2 lb) mass, is an example of a large picosatellite (or minimum nanosat).
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 (0.22–2.2 lb). 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 between 10 and 100 g (0.35 and 3.5 oz). 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 March 2014, the nanosatellite KickSat was launched aboard a Falcon 9 rocket with the intention of releasing 104 femtosatellite-sized chipsats, or "Sprites". ThumbSat is another project intending to launch femtosatellites in 2016.
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Small satellites usually require innovative propulsion, attitude control, 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.
- Konecny, G. "Small satellites–A tool for Earth observation?" (PDF).
- "2014 Nano/Microsatellite Market Assessment" (PDF). annual market assessment series. Atlanta, Georgia: SEI. January 2014: 18. Retrieved 18 February 2014.
- Messier, Doug (2 March 2015). "Euroconsult Sees Large Market for Smallsats". Parabolic Arc. Retrieved 8 March 2015.
- Foust, Jeff (12 June 2015). "Smallsat Developers Enjoy Growth In Launch Options". Space News. Retrieved 13 June 2015.
- "Small Is Beautiful: US Military Explores Use of Microsatellites". Defense Industry Daily. 30 June 2011. Retrieved 12 December 2012.
- Tristancho, Joshua; Gutierrez, Jordi (2010). "Implementation of a femto-satellite and a mini-launcher" (PDF). Universitat Politecnica de Catalunya: 3. Retrieved 12 December 2012.
- Werner, Debra (12 August 2013). "Small Satellites & Small Launchers: Rocket Builders Scramble To Capture Growing Microsat Market". Space News. Retrieved 1 November 2013.
- "Virgin Galactic relaunches its smallsat launch business". NewSpace Journal. 12 July 2012. Retrieved 11 July 2012.
- EXCLUSIVE: Virgin Galactic unveils LauncherOne name!, Rob Coppinger, Flightglobal Hyperbola, 9 December 2008
- "Alpha". Firefly Space Systems. Retrieved 9 May 2014.
- "Electron". Rocket Lab. 15 February 2016.
- Peláez, Javier. "PLD Space, la empresa española camino de lanzar satélites e incluso alcanzar la Luna". Yahoo noticias. Yahoo. Retrieved 19 April 2016.
- Boyle, Alan (4 June 2015). "How SpaceX Plans to Test Its Satellite Internet Service in 2016". NBC News. Retrieved 5 June 2015.
- Gruss, Mike (21 March 2014). "DARPA Space Budget Increase Includes $27M for Spaceplane". Space News. Retrieved 24 March 2014.
- Burn-Callander, Rebecca (22 August 2015). "Virgin Galactic boldly goes into small satellites, telling future astronauts 'you have to wait'". UK Telegraph. Retrieved 24 August 2015.
- Lindsey, Clark (19 December 2012). "DARPA developing microsat constellation orbited with air-launch system". NewSpace Watch. Retrieved 22 December 2012. (subscription required (. ))
- Gruss, Mike (30 November 2015). "DARPA Scraps Plan To Launch Small Sats from F-15 Fighter Jet". SpaceNews.
- Messier, Doug (4 April 2013). "Garvey Nanosat Launcher Selected for NASA SBIR Funding". Parabolic Arc. Retrieved 5 April 2013.
- Norris, Guy (21 May 2012). "Boeing Unveils Air-Launched Space-Access Concept". Aviation Week. Retrieved 23 May 2012.
- Painter, Kristen Leigh (8 October 2013). "Spaceport Colorado lands agreement with Swiss space company Read more: Spaceport Colorado lands agreement with Swiss space company". The Denver Post. Retrieved 21 October 2013.
- Verhoeven, C.J.M.; Bentum, M.J.; Monna, G.L.E.; Rotteveel, J.; Guo, J. (April–May 2011). "On the origin of satellite swarms". Acta Astronautica. 68 (7-8): 1392–1395. doi:10.1016/j.actaastro.2010.10.002.
- Tsitas, S. R.; Kingston, J. (February 2012). "6U CubeSat commercial applications". The Aeronautical Journal. 116 (1176): 189–198.
- Barron, Rachel (6 April 2015). "Spire's Peter Platzer: the boss who never fires anyone". The Gaurdian. Retrieved 21 April 2016.
- "Nanosats are go!". Technology Quarterly Q2 2014. The Economist. 7 June 2014. Retrieved 12 June 2014.
- Messier, Doug (11 October 2013). "NovaWurks Awarded Contract for DARPA Phoenix Project". Parabolic Arc. Retrieved 13 October 2013.
- Cheredar, Tom (9 October 2013). "Dauria Aerospace lands $20M to grow its earth-monitoring nano satellite platform". VentureBeat. Retrieved 13 October 2013.
- Woo, Marcus (20 December 2014). "Designing a Mothership to Deliver Swarms of Spacecraft to Asteroids". Wired. Retrieved 17 December 2014.
- Amos, Jonathan (11 July 2012). "Richard Branson's Virgin Galactic to launch small satellites". BBC News. Retrieved 13 July 2012.
- Messier, Doug (2 July 2012). "DARPA Awards 6 Small Airborne Launch Vehicle Contracts". Parabolic Arc. Retrieved 29 November 2012.
- Lindsey, Clark (28 January 2013). "North Star rocket family with hybrid propulsion". NewSpace Watch. Retrieved 28 January 2013. (subscription required (. ))
- "DIY Satellite Platforms". KK Technium. Retrieved 12 December 2012.
- Elizabeth Simpson (16 May 2011). "Chip satellites -- designed to blow in the solar wind -- depart on Endeavour's final launch". Cornell Chronicle. Retrieved 6 December 2012.
- Clark, Stephen (13 April 2014). "Crowd-funded stowaway to deploy 104 tiny satellites". Spaceflight Now. Retrieved 15 May 2014.
- "KickSat Nanosatellite Mission". European Space Agency. Retrieved 15 May 2014.
- Jon Lackman (13 October 2015). "Itty-Bitty Satellites Could Carry Your Experiments to Space". Wired. Retrieved 21 February 2016.