We tend to think of satellites as huge spacecraft that tower over the engineers who build them. Consider Envisat, SOHO and GOCE — all ESA satellites similar in size to a small bus. But over the last twenty years, miniature satellites called CubeSats have been shaking up the space industry, making accessing space easier and cheaper for those who could previously only dream of it.
CubeSats are typically built up from standard cubic units each measuring 10 cm x 10 cm x 10 cm — just a bit bigger than a Rubik’s cube! The number of units depends on the CubeSat’s mission, but tends to be between 2 and 12 resulting in a mass of just 1–10 kg. These little satellites have a fraction of the mass, and cost, of more traditional satellites.
Having initially been developed as educational tools, CubeSats are increasingly being put to active use in orbit for technology demonstration, scientific studies, and even commercial purposes. And just like typical satellites, they are custom built to fulfil the specific requirements of their mission.
CubeSats tend to hitch a ride into space using extra space available on rockets, meaning lots of launch opportunities and low launch costs. They are packed in a container which, at the push of a button, ejects them into space via a spring system. A similar technique is also used to deploy CubeSats from the International Space Station (ISS), where they are launched out of the Japanese module, Kibo.
These small satellites provide affordable access to space for small companies, research institutes and universities. Their modular design means that subsystems are available off-the-shelf from different suppliers and can be stacked together according to the needs of the mission. This allows CubeSat projects to be readied for flight extremely quickly — typically within one or two years.
CubeSats are now commonly used in low Earth orbit for applications such as remote sensing and communications. But as engineers become more familiar with the technology, plans are in place for CubeSats to begin venturing farther afield. Whether it’s to the Moon, Mars, or even further, these tiny spacecraft are certainly changing the game when it comes to space exploration.
WHY IS ESA INTERESTED IN CUBESATS?
ESA began giving university students the chance to develop their own space mission when it kicked off its CubeSat education programme — Fly your Satellite! — in 2013. Many Fly your Satellite! alumni have gone on to create their own companies which now form the basis of the CubeSat industry! CubeSat’s have clearly proven their worth as educational tools, but ESA is also using CubeSats for professional space missions.
Not only do CubeSats provide an affordable means of demonstrating exciting new technologies, they also drive the drastic miniaturisation of systems and encourage a new approach to spacecraft integration. They can obtain simultaneous in-situ observations of their surroundings and give us an affordable way to deploy small payloads. But perhaps most exciting in terms of science, CubeSats bring versatility to space exploration that could help us find out lots more about the Solar System.
DISCOVERY AND PREPARATION ACTIVITIES
Under ESA’s Discovery and Preparation activities many CubeSat-focussed studies have been funded and “technology challenges” are regularly opened to get the most brilliant proposals for new space technology.
Based on ESA’s previously proposed Asteroid Impact Mission (AIM), Hera is part of the international Asteroid Impact and Assessment Mission (AIDA), in collaboration with NASA/JPL. The American DART impactor will hit the moon of a binary asteroid system called Didymos, and Hera will watch the aftermath to study this type of asteroid deflection. Hera has three objectives: to demonstrate technology in interplanetary space, to investigate Near-Earth Object mitigation techniques, and to gain new insight into the evolution of the Solar System. As part of this mission, ESA plans to partner Hera with two six-unit CubeSats, giving European scientists their first chance to operate CubeSats in deep space.
LUnar CubeSats for Exploration (LUCE)
To support ESA’s lunar exploration objectives, four innovative CubeSat concepts were recently selected for possible flight over the coming decade. The LUCE CubeSats would piggy-back on a lunar transfer vehicle before being released into orbit around the Moon.
In 2020, ESA will launch SpectroCube, a mission that will travel far from Earth to carry out astrobiology and astrochemistry experiments. The key science objectives of SpectroCube are to assess the impact of space on the biology and chemistry of the building blocks of life.
ESA’s CDF has also been assessing the feasibility of the Miniaturised Asteroid Remote Geophysical Observer (M-ARGO), a stand-alone deep space CubeSat which would meet and characterise a near-Earth object. M–ARGO is intended to investigate the potential of using miniaturised technologies to lower the entry-level cost of space exploration.
In 2014, ESA welcomed teams of scientists to design a project that would use cooperative nanosatellites for Earth Observation. This resulted in the NAnosatellite Multiple channel Earth Observation (NAME-O) — a mission designed to carry out remote sensing using five cooperative nanosatellites.
ESA-WIDE USE OF CUBESATS
Over the past five years, ESA has been putting more time and effort into its CubeSat activities. Roger Walker, head of ESA’s CubeSat efforts, explains that “ESA is harnessing CubeSats as a fast, cheap method of testing promising European technologies in orbit”.
ESA’s first CubeSat project was GomX-3, a mission to demonstrate various signal monitoring technologies, which was deployed from the ISS in October 2015. Consisting of twin CubeSats, GomX-3’s successor GomX-4 will monitor Arctic territory and test radio links in space across distances of up to 4500 km. One of the twins can also adjust its orbit using cold-gas thrusters, opening up the prospect of rapidly deploying future constellations, maintaining their separations, and flying them in formations to perform new types of measurements from space.
Other ESA-funded CubeSat missions include:
- QARMAN – demonstrates re-entry technologies, particularly novel heatshield materials, a new passive aerodynamic drag stabilisation system, and the transmission of telemetry data during re-entry via data relay satellites in low-Earth orbit
- SIMBA – measures the power of the Sun and the balance between incoming energy from the Sun and the outgoing energy from Earth.
- PICASSO – measures ozone distribution in the stratosphere, the temperature profile of the mesosphere, and electron density in the ionosphere.
- RadCube – demonstrates miniaturised instrument technologies that monitor space weather.
- PRETTY – demonstrates a novel technique used primarily to detect sea ice, and tests a miniaturised radiation dosimeter.
WHAT ARE OTHER SPACE AGENCIES DOING IN THIS AREA?
NASA runs the extensive Small Spacecraft Technology Program as well as the CubeSat Launch Initiative. Previously selected CubeSats have studied near-Earth objects, space weather, Earth’s atmosphere and much more.
This year, NASA launched its first pair of CubeSats designed for deep space — Mars Cube One, or MarCO. Both satellites hitched a ride on the rocket launching InSight, NASA's latest Mars lander. The MarCO CubeSats intend to follow InSight on its cruise through space; once they have arrived, each will relay data back to Earth as InSight enters the Martian atmosphere and lands.
Another NASA CubeSat mission, GTOSat, will observe the forbidding radiation belts that circle Earth, and the Agency is also planning a CubeSat mission to the Moon which will navigate in space using pulsars. NASA’s innovative mission NEA Scout will be the first to use a solar sail for propulsion. When deployed, the sail — square in shape with each side about the length of a school bus — will use solar energy to propel itself through space.
Currently, CubeSats are deployed from the ISS via the Japanese module, Kibo. The Japanese Space Agency has collaborated with the United Nations Office for Outer Space Affairs (UNOOSA) to set up KiboCUBE, a project that offers developing countries the opportunity to deploy their own CubeSats from the ISS. The Canadian Space Agency run the Canadian CubeSat Project which aims to engage students in a real space mission, and last year the Russian space agency developed the world’s first CubeSat to be produced entirely with a 3D printer, resulting in a stronger, lighter structure.
A 'PEEK' INTO THE FUTURE
As a first test of a new printable, hard and electrically conductive plastic called PEEK, ESA has been 3D-printing CubeSat structures incorporating their own electrical lines. In future, such miniature satellites could be ready to go once their instruments, circuit boards and solar panels are slotted in.