An American firm, Spire Global, is in the business of putting large numbers of its tiny Lemur (Low Earth Multi-Use Receiver satellites) CubeSats to monitor weather as well as maritime traffic. While calibrating the electronics in the first of their Lemur CubeSats they discovered another use, and customer, for Lemur; detecting GPS jamming and other forms of electronic warfare. Now Spire has several additional customers, U.S. government agencies that exist to detect and deal with jamming, especially of satellite signals.
Lemur uses a technique called reflectometry that, from space, detects and measures weak electronic signals broadcast from space, like GPS, and measures the return signal from the planet surface to obtain more detailed and accurate weather patterns and. Another type of Lemur is equipped to detect and monitor moving objects at sea.
Reflectometry is something like passive (listen only) sonar, radar and thermal systems. Collecting this data simultaneously on a global scale creates better weather forecasting data, especially for ocean shipping as well as better current data for mapmakers. Spire Global uses commercial technology to build its Lemur satellites but now has a division that works with Western intelligence agencies to determine how much they can use Lemur data or how Lemur satellites can be equipped to detect even more information about jamming, like the location of the earth based jammers and other forms of electronic warfare.
Current Lemur CubeSats weigh eight kg (17.6 pound) each and are classified as U class spacecraft. This is based on the standard for the smallest (1U) CubeSat which is volume no more than one liter (10x10cm or 4.1x4.1 inches) and weigh no more than 1.3 kg (three pounds). A 3U CubeSat is three times the volume of a 1U version. Currently the largest CubeSats are 6U.
Spire Global was founded in the U.S. during 2012 and has since established facilities in Britain and Luxembourg. Spire Global is one of many new firms taking advantage of advances in microelectronics and small satellite technology. These trends have revolutionized space satellite design and capabilities.
In the late 1990s several countries in the West (especially the U.S.) began developing very small satellites mainly because the technology had improved to the point where small was affordable and useful. The earliest of these ultra-small satellite designs was developed by the U.S. Department of Defense and were called CubeSats. The military got the idea from the increasing use of commercial nanosatellites that weigh no more than 6.8 kg (15 pounds). The U.S. military launched its first CubeSats in 2008, piggybacking with a larger satellite that had unused space in the payload nosecone.
It was quickly verified that CubeSats could be used for photo or electronic surveillance, or communications. Rapid advances in communications and sensor technology in the early 21st century made it possible to build a useful reconnaissance satellite weighing less and less. A tiny satellite like this includes solar panels to provide power.
A British firm pioneered this ultra-small satellite technology in the 1990s and made it possible to get scientific satellites in orbit for a fraction of the usual price. Since 2008 over a thousand CubeSats (or similar designs) have been launched and the number is increasing each year. Most of the 173 micro-satellites carried by the recent Soyuz and PSLV launches were based on the CubeSat design. That standardization also allowed for the establishment of standards for placing many micro-satellites in a rocket's final stage, another factor in keeping delivery costs down.
Spire Global has been a major participant in this and now has over a hundred Lemurs in orbit, each carrying either a weather, maritime traffic or air traffic sensing payload. Lemurs are powered by solar arrays and battery back-up and operate in LEO (Low Earth Orbits) of 500 kilometers or less. The lower the orbit the more efficient the onboard sensors are at collecting electronic signals on earth. Lemur-2 satellites have a useful life of two years, and operate in separate constellations of a dozen or more satellites. Each constellation must be constantly refreshed with new satellites and this makes it easier to upgrade constellation capabilities.
CubeSats are now technically U Class spacecraft and have standard weight and dimensions. Larger (6U) CubeSats, which weigh 8 kg (13.2 pounds) and handle a lot of jobs that previously needed a much larger and heavier satellite. CubeSats of all sizes are increasingly popular for science experiments by smaller organizations, or even individuals, who cannot afford a multi-million- dollar satellite that is ten or more times larger and heavier than a CubeSat. Over 1,400 CubeSats have been launched since 1998, with about 93 percent reaching orbit. That number is expected to double in the next few years because more and more commercial satellite launchers are providing unused space and weight on their launcher rockets for carrying and launching some CubeSats. In some cases, the CubeSat owners pay for this service while in other cases some CubeSats are taken up for free, as a public service.