When you think of telescopes in space, you probably think of the Hubble Space Telescope and its younger, larger sibling, the James Webb Space Telescope.

Both are multi-billion-dollar international missions, and both have impressively sized telescope mirrors to match that expensive price tag.

The underside of a small orbiting satellite looking towards Earth — The first image taken by the SpIRIT selfie camera, acquired over New Zealand at the end of the thermal radiator deployment sequence. The image includes mission participant logos and the electric propulsion thruster payload of SpIRIT (cylindrical aperture near the bottom) and telecommunication transceivers (diamond patches and antennae). The backs of the solar panels are also visible. Picture: University of Melbourne

While these superstars of space-based astronomy are flagships for their fields, you don’t need enormous, expensive telescopes to do innovative research in space.

You just need the right tool for the right job. This is exactly the approach of a small Australian space telescope called the Space Industry Responsive Intelligent Thermal (SpIRIT) satellite, which has been quietly orbiting the Earth for over 600 days.

On the hunt for colliding stars

A new era of astronomy was born in 2017, when for the first time, an astrophysical event – the violent merger of two neutron stars – was observed with the simultaneous detection of light and of gravitational waves.

This was the dawn of ‘Multi-messenger Astronomy’.

The light was detected by the orbiting gamma ray observatories Fermi and INTEGRAL, and the gravitational waves were measured by the Laser Interferometer Gravitational Wave Observatory (LIGO) on Earth.

This was a monumental achievement, but also a bit of a fluke.

An artist's picture of the Earth surrounded by debris

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If we don’t know where and when a cataclysmic event like a neutron star merger will happen ahead of time, trying to see it with a space telescope at the same time that observatories like LIGO detect the gravitational waves on Earth is a bit like searching for a needle in a haystack.

Unless of course, you change the way you think about a space telescope.

Just like technology has miniaturised on Earth in recent years – think of the supercomputer in your pocket – spacecraft are getting smaller.

This miniaturisation has enabled the phenomenon of satellite constellations – groups of multiple small satellites operating together to achieve a single goal.

Taking advantage of this concept, HERMES (High Energy Rapid Modular Ensemble of Satellites) is an international mission led by the Italian Space Agency to fly a constellation of X-ray space telescopes to monitor the entire sky for events like neutron star mergers.

HERMES trades the power and resolution of larger, more traditional space telescopes for the ability to cover large swathes of the sky simultaneously.

Earth from space with the moon in the distance — The Earth and the Moon, taken from the SpIRIT satellite. Picture: University of Melbourne

It acts as an all-sky early warning system for larger space telescopes, which can respond to HERMES detection alerts and follow up with more detailed observations.

Through a collaboration between the Italian and Australian Space Agencies, the very first of these next-gen X-ray space telescopes is on board SpIRIT.

SpIRIT’s first target is the Crab Pulsar, a rapidly spinning neutron star at the heart of the Crab Nebula. The pulsar ejects beams of radiation as it rotates, making it appear to pulse, like a galactic lighthouse, at a steady 30 times per second.

SpIRIT detects and records high-energy photons from the pulsar, and this data is then analysed by the Italian Space Agency to produce an energy spectrum of the pulsar.

Astronomy driving Australian innovation

SpIRIT was the first spacecraft funded by the Australian Space Agency. It is also the first Australian spacecraft to host an international payload, made possible by an array of Australian space industry technologies.

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The commercial spacecraft system Apogee, developed by Inovor Technologies, provides power, attitude control and telemetry.

Ion thrusters developed by Neumann Space allow the satellite to orient itself in orbit and point the space telescope towards different targets.

A Nova Ground Station provides a reliable connection to the on-ground team for commands and to downlink data.

The University of Melbourne Space Lab developed the Themis thermal management system, which is being flown in space for the first time.

Themis is used to cool the HERMES detector, providing resilience in the harsh radiation environment of Low Earth Orbit.

Themis is one of the first examples of active thermal management in space on board such a small satellite.

A dark Earth from space with a slither of light lighting its edge — A slither of sunshine shows the edge of Earth's atmosphere, known as Earth's limb. Picture: University of Melbourne

Thriving in a harsh environment

Simply surviving in space is an achievement.

Close to 50 per cent of small satellites fail when they reach orbit, and the past few years have been the most hostile in recent history for Low Earth Orbiting satellites like SpIRIT, because the Sun has reached the peak of its solar cycle.

Violent solar storms have sent out clouds of charged particles, and people on Earth have enjoyed vivid aurora displays at latitudes not seen for decades.

While beautiful, these events cause havoc for satellites, messing with their onboard electronics and puffing up the Earth’s atmosphere, which causes satellites to slow down and drop closer to Earth.

SpaceX lost up to 40 Starlink satellites during solar storms in 2022.

Despite the challenges that satellites experience in orbit, SpIRIT has continued to operate for nearly two years.

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Postcards from space

SpIRIT was designed with a comprehensive suite of cameras that are used to inspect the satellite whilst in orbit.

These include an array of optical and thermal infrared imaging cameras, which help to monitor the performance of the Themis thermal management system.

We’ve been using these cameras to observe Earth in the optical and infrared wavelengths, and we hope to use these observations to further explore the development of sovereign remote seeing capabilities, thermal infrared bushfire detection and space domain awareness.

SpIRIT has now entered the final phase of the mission and successfully deployed two radiators, which will test the full extent of the thermal management system.

A degraded image of the underside of a small orbiting satellite looking towards Earth — SpIRIT flying over Australia, looking towards the Gulf of Carpentaria and Cape York Peninsula, 42 days after deployment of the selfie camera. Despite being exposed to the harsh environment of space with extreme temperature swings that far exceeds its nominal survival range, the camera has far exceeded its expected lifetime of about one hour, and continues to operate reasonably well, albeit with some degradation of image quality. It is a remarkable achievement for made in Australia space technology. Picture: University of Melbourne

Safely tucked under these radiators was the WallE selfie camera, which had also successfully deployed, allowing SpIRIT to send photos of itself in space back to an excited team on Earth.

The past 600 days have been a wild ride for the SpIRIT team, and we are looking forward to another year exploring the universe.

SpIRIT will naturally lower its orbit over the next few months as it interacts with the Earth’s atmosphere.

At the end of the mission, the satellite will burn up in the atmosphere, ensuring no space junk is left behind, and having taken only pictures.

Banner: SpIRIT’s radiators after deployment, flying high over the Indian Ocean. The ‘Eagle’, a copper structure on the right radiator can be seen, which is designed to help dissipate heat from SpIRIT’s thermal management system.

This article was first published on Pursuit. Read the original article.

Sarah Caddy

Research Fellow, Melbourne Space Laboratory

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