Space invaders: Mini satellite swarm

November 22, 2017

An international project to study Earth’s poorly understood thermosphere uses a swarm of satellites – two of which were built at UNSW.

Elias Aboutanios space invaders satellite

Don’t be fooled by the diminutive size of the UNSW-EC0 cubesat. This 1.8kg miniature satellite may be small, but the team who built it have high ambitions.

The miniature satellite is part of the European-led QB50 mission to explore Earth’s least understood atmospheric layer: the thermosphere. Built by a team at Sydney’s Australian Centre
for Space Engineering Research (ACSER), the satellite was deployed, along with a constellation of 35 other cubesats, from the International Space Station in June 2017.

The thermosphere, between 200 and 380km above Earth, is a region vital for communications and weather formation and helps shield Earth from radiation from the Sun and harsh cosmic rays – a region where temperatures can hit 2,500˚C (4,500˚F). It’s here auroras form their flickering curtains of light, and where ultraviolet and X-ray radiation from the Sun can cause potentially catastrophic solar storms that can knock out power grids and communications. Yet until now, the region has been largely uncharted.  

The objective of the QB50 project, led by Belgium’s Von Karman Institute for Fluid Dynamics and involving 28 nations, is to understand the atomic composition of this region. UNSW-EC0 carries a miniaturised Ion Neutral Mass Spectrometer that will collect measurements useful for weather modelling and prediction. 

“This is the most extensive exploration of the lower thermosphere ever, collecting measurements in the kind of detail never before tried,” says Elias Aboutanios, UNSW-EC0’s project leader. “The satellites will operate for three to nine months – and may stay up for up to a year – before their orbits decay and they re-enter the atmosphere and burn up.”

As it drifts lower, the satellite will measure various points of the thermosphere and send the data to a global network of ground stations.

The ACSER team packed other unique experiments aboard UNSW-EC0. It carries UNSW’s new Namuru space-borne GPS, much more accurate thanks to higher-resolution positioning, which is needed in space, especially for formation flying of satellites planned for the future.

Another technology being tested is the seL4bit SBC, a super reliable capability-based software microkernel developed at UNSW; and the RUSH Field-Programmable Gate Array, a robust chip designed to self-correct errors caused by random cosmic rays in space, which can scramble today’s computer chips. It is designed to self-correct errors and allow rapid recovery from a glitch without shutting down or stopping what it is doing, and is a novel, and potentially valuable, approach being tested in space for the first time.

In another first, the team 3D-printed the satellite’s metal-coated thermoplastic skin, in a new process dubbed RAMSES (Rapid Manufacture of Space-Exposed Structures). This allows for greater customisation, while both speeding up the production rate and lowering costs, says technical lead Joon Wayn Cheong. If UNSW-EC0 holds up and performs as planned, the 3D-printed cubesat could be the model for future, more ambitious designs.

Eyes on the sky

Three Australian cubesats were built for the QB50 project, two of them at ACSER, and they are the first satellites made locally in 15 years. But there are likely to be many more.

“It’s an example of the philosophy behind ‘Space 2.0’, where the big expensive agency-driven satellites are being replaced by disruptive low-cost access to space,” says Andrew Dempster, Director of ACSER.

Its other QB50 cubesat was INSPIRE-2, developed jointly with the University of Sydney and Canberra’s Australian National University. This cubesat will measure the plasma density and electron temperature in the thermosphere.

“The QB50 mission is an opportunity to show what we can do at ACSER,” adds Dempster.

ACSER is also a partner in Biarri, a cubesat mission for the Five Eyes intelligence alliance of Australia, New Zealand, Canada, the UK and the USA, to explore cubesat formation flying, verify the performance of UNSW’s Namuru GPS receivers and improve electro-optic systems used for precision orbital tracking. And ACSER is a global leader in the emerging field of off-Earth mining, holding annual forums at which international participants explore how to mine space for water and minerals. It has constructed risk-based financial and technical models to evaluate multiple space-borne mining scenarios, and developed optimised mining systems to extract water on Mars.

Read about the five steps Australia can take to build an effective space agency here.

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