Miniaturized satellite

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Miniaturized satellites or small satellites are artificial satellites of lower weights and smaller sizes, usually under 500 kg (1,100 lb).^[1] While all such satellites can be referred to as small satellites, different classifications are used to categorize them based on mass (see below).

One reason for miniaturizing satellites is to reduce the cost: heavier satellites require larger rockets with greater thrust which also has greater cost to finance. In retrospect, 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.

Besides the cost issue, the main rationale for the use of miniaturized 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

Classification groups

3 microsatellites of Space Technology 5

Minisatellite

The term "minisatellite" usually refers to an artificial satellite with a "wet mass" (including fuel) between 100 and 500 kg (220 and 1,100 lb),^{[citation needed]} though these are usually simply called "small satellites". Minisatellites are usually simpler but use the same technologies as larger satellites.

Examples: Demeter, Essaim, Parasol, Picard, Microscope, Taranis, Elisa, Smese, SSOT, Smart-1, Spirale, Jason-1, Jason-2.

Microsatellite

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).^{[citation needed]} However, this is not an official convention and sometimes microsats can refer to satellites larger than that. Sometimes designs or proposed designs of these types have microsatellites working together or in a formation. The generic term "small satellite" is also sometimes used.

Except the mass, the size of satellite is important too.

Examples: Astrid-1 and Astrid-2.

Nanosatellite

The term "nanosatellite" or "nanosat" is usually applied to an artificial satellite with a wet mass between 1 and 10 kg (2.2 and 22 lb).^{[citation needed]} Again designs and proposed designs of these types usually have multiple nanosatellites 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 nanosatellites.

Picosatellite

Picosatellite or "picosat" (not to be confused with the PicoSAT series of microsatellites) is usually applied as the name of an artificial satellite with a wet mass between 0.1 and 1 kg (0.22 and 2.2 lb).^{[citation needed]} 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).^{[citation needed]}

Molecularsatellite

Molecularsatellite or "molesat" is usually applied as the name of an artificial satellite with at least one dimension sized from 100 to 10000 nanometres with a wet mass between .001 gram and 10.0 grams. Current designs of this class of nanotech satellite work together in an amplification formation an asterism pattern (sometimes the term "constellation" is applied). Proposed designs require an asterism with a larger "picosat" satellite amongst its formation for amplified communication with ground transponders. Molesats have the capacity to act either as a passive or active satellite:^{[citation needed]}

(a) Passive Satellites: Satellites which reflect the incident electromagnetic radiation without any modification or amplification. Passive satellites can't generate power they simply reflect the incident power.

(b) Active satellites: Satellites which can transmit power are called active satellite. They can amplify or modify the incident signal for transmission.

Technical challenges

Micro/nanosats usually require innovative propulsion, attitude control, communication and computation systems.

Larger satellites usually use monopropellants or bipropellant combustion rockets for propulsion and attitude control; these systems are complex and require a minimal amount of volume to surface area to dissipate heat. These systems are used on larger microsats, 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.

Microsats can use conventional radio systems in UHF, VHF, the 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 a 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.

Some manufacturers

Manufacturers of microsatellites include SpaceDev and Surrey Satellite Technology Ltd.

Manufacturers of nanosatellites include GomSpace, ISIS and UTIAS-SFL.

Manufacturers of molecularsatellites include Nanotsat Group

SuitSat, a retired spacesuit fitted with some basic instrumentation and radio transmitting equipment and released into orbit in 2006, was an unconventional example of a low-cost microsatellite test platform.

See also

Spaceflight portal

References

External links

• Edusat Project
• http://marsnet.jpl.nasa.gov/index.html
• http://www.accessscience.com/ResUpdates/2004/YB_041170_frameset.html?doi
• Teich's Tech Tidbit of the Week December 13, 1999 Nanosats