Femtosat

A small satellite, miniaturized satellite, or smallsat is a satellite of low mass and size, usually under . 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.

Rationales

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

History

The nanosatellite and microsatellite segments of the satellite launch industry have been growing rapidly in recent years. Development activity in the range has been significantly exceeding that in the range.

In the range alone, fewer than 15 satellites were 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 2015–2019 with a market value estimated at .

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.

Classification groups

Small satellites

The term "small satellite", or sometimes "minisatellite", often refers to an artificial satellite with a wet mass (including fuel) between , but in other usage has come to mean any satellite under .

Small satellite examples include Demeter, Essaim, Parasol, Picard, MICROSCOPE, TARANIS, ELISA, SSOT, SMART-1, Spirale-A and -B, and Starlink satellites.

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 (300 kg)
*Virgin Orbit's LauncherOne (500 kg)
*Astra's Rocket 3.3 (100 kg)
*Vaya Space's Dauntless (1000+ kg LEO 600+ kg SSO)

Microsatellites

The term "microsatellite" or "microsat" is usually applied to the name of an artificial satellite with a wet mass between . However, this is not an official convention and sometimes those terms can refer to satellites larger than that, or smaller than that (e.g., ). 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".

Examples: Astrid-1 and Astrid-2, as well as the set of satellites currently announced for ''LauncherOne'' (below)

In 2018, the two Mars Cube One microsats—massing just 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