CubeSat

A CubeSat (U-class spacecraft) is a type of miniaturized satellite for space research that is made up of multiples of 10 cm × 10 cm × 11.35 cm (~ 4 in × 4 in × 4.5 in) cubic units. CubeSats have a mass of no more than 1.33 kilograms (2.9 lb) per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats are commonly put in orbit by deployers on the International Space Station, or launched as secondary payloads on a launch vehicle. Over 1000 CubeSats have been launched as of January 2019. Over 900 have been successfully deployed in orbit and over 80 have been destroyed in launch failures. A CubeSat (U-class spacecraft) is a type of miniaturized satellite for space research that is made up of multiples of 10 cm × 10 cm × 11.35 cm (~ 4 in × 4 in × 4.5 in) cubic units. CubeSats have a mass of no more than 1.33 kilograms (2.9 lb) per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats are commonly put in orbit by deployers on the International Space Station, or launched as secondary payloads on a launch vehicle. Over 1000 CubeSats have been launched as of January 2019. Over 900 have been successfully deployed in orbit and over 80 have been destroyed in launch failures. In 1999, California Polytechnic State University (Cal Poly) and Stanford University developed the CubeSat specifications to promote and develop the skills necessary for the design, manufacture, and testing of small satellites intended for low Earth orbit (LEO) that perform a number of scientific research functions and explore new space technologies. Academia accounted for the majority of CubeSat launches until 2013, when more than half of launches were for non-academic purposes, and by 2014 most newly deployed CubeSats were for commercial or amateur projects. Uses typically involve experiments that can be miniaturized or serve purposes such as Earth observation or amateur radio. CubeSats are employed to demonstrate spacecraft technologies intended for small satellites or that present questionable feasibility and are unlikely to justify the cost of a larger satellite. Scientific experiments with unproven underlying theory may also find themselves aboard CubeSats because their low cost can justify higher risks. Biological research payloads have been flown on several missions, with more planned. Several missions to the Moon and Mars are planning to use CubeSats. In May 2018, the two MarCO CubeSats became the first CubeSats to leave Earth orbit, on their way to Mars alongside the successful InSight mission. Some CubeSats became the first national satellites of their countries, being launched by universities, state, or private companies. The searchable Nanosatellite and CubeSat Database lists over 2,000 CubeSats that have been and are planned to be launched since 1998. Professors Jordi Puig-Suari of California Polytechnic State University and Bob Twiggs of Stanford University proposed the CubeSat reference design in 1999:159 with the aim of enabling graduate students to design, build, test and operate in space a spacecraft with capabilities similar to that of the first spacecraft, Sputnik. The CubeSat, as initially proposed, did not set out to become a standard; rather, it became a standard over time by a process of emergence. The first CubeSats launched in June 2003 on a Russian Eurockot, and approximately 75 CubeSats had entered orbit by 2012. The need for such a small-factor satellite became apparent in 1998 as a result of work done at Stanford University's Space System Development Laboratory. At SSDL, students had been working on the OPAL (Orbiting Picosatellite Automatic Launcher) microsatellite since 1995. OPAL's mission to deploy daughter-ship 'picosatellites' had resulted in the development of a launcher system that was 'hopelessly complicated' and could only be made to work 'most of the time'. With the project's delays mounting, Twiggs sought DARPA funding that resulted in the redesign of the launching mechanism into a simple pusher-plate concept with the satellites held in place by a spring-loaded door.:151–157 Desiring to shorten the development cycle experienced on OPAL and inspired by the picosatellites OPAL carried, Twiggs set out to find 'how much could you reduce the size and still have a practical satellite'. The picosatellites on OPAL were 10.1 cm × 7.6 cm × 2.5 cm (4 in × 3 in × 1 in), a size that was not conducive to covering all sides of the spacecraft with solar cells. Inspired by a 4-inch (10 cm) cubic plastic box used to display Beanie Babies in stores, Twiggs first settled on the larger 10-centimeter cube as a guideline for the new (yet-to-be-named) CubeSat concept. A model of a launcher was developed for the new satellite using the same pusher-plate concept that had been used in the modified OPAL launcher. Twiggs presented the idea to Puig-Suari in the summer of 1999 and then at the Japan–U.S. Science, Technology and Space Applications Program (JUSTSAP) conference in November 1999.:157–159 The term 'CubeSat' was coined to denote nanosatellites that adhere to the standards described in the CubeSat design specification. Cal Poly published the standard in an effort led by aerospace engineering professor Jordi Puig-Suari. Bob Twiggs, of the Department of Aeronautics & Astronautics at Stanford University, and currently a member of the space science faculty at Morehead State University in Kentucky, has contributed to the CubeSat community. His efforts have focused on CubeSats from educational institutions. The specification does not apply to other cube-like nanosatellites such as the NASA 'MEPSI' nanosatellite, which is slightly larger than a CubeSat. GeneSat-1 was NASA's first fully automated, self-contained biological spaceflight experiment on a satellite of its size. It was also the first U.S.-launched CubeSat. This work, led by John Hines at NASA Ames Research, became the catalyst for the entire NASA CubeSat program. The CubeSat specification accomplishes several high-level goals. The main reason for miniaturizing satellites is to reduce the cost of deployment: they are often suitable for launch in multiples, using the excess capacity of larger launch vehicles. The CubeSat design specifically minimizes risk to the rest of the launch vehicle and payloads. Encapsulation of the launcher–payload interface takes away the amount of work that would previously be required for mating a piggyback satellite with its launcher. Unification among payloads and launchers enables quick exchanges of payloads and utilization of launch opportunities on short notice.