Australia’s first nanosatellite begins observing the universe’s most extreme events

When the SpIRIT CubeSat rode into orbit on a SpaceX Falcon 9 in December 2023, it carried a very massive passenger along. Cramped inside the shoebox-sized satellite is the HERMES detector, an instrument built by the Italian Space Agency that can capture incoming particles from some of the universe's most energetic occurrences. No bigger than a box of tissues, yet this tiny device can measure X-rays and gamma rays from distant, violent explosions.

One of the many features that distinguish HERMES is the quantity of technology that is crammed into such a small instrument. It employs silicon drift detectors to identify soft X-rays, as well as scintillating crystals that radiate light when they are struck by more energetic gamma rays. This allows the instrument to identify signals that range from a few thousand electron volts up to two million.

In spite of this wide range, the instrument weighs only about a kilogram and a half, consumes only two watts of electricity, and can measure the arrival of the cosmic bursts to within a millionth of a second.

That accuracy in timing is crucial because SpIRIT is not moving on its own. It is part of a fleet of satellites carrying HERMES detectors aboard. By observing when bursts arrive at each satellite, astronomers will be able to pinpoint the source of these cosmic fireworks.

For Australia, SpIRIT is a landmark. It is the first Australian Space Agency-funded space telescope to host another country's main science payload. Conceived and led by the University of Melbourne, the nanosatellite showcases Australia's growing contribution to international space science.

Since it went into orbit, SpIRIT has completed over 9,000 orbits, a distance equivalent to one round trip to Mars and back. Now, after several months of careful testing, it has successfully gone through its commissioning phase and is now ready to begin its primary science mission.

The mission's lead investigator at the University of Melbourne, Professor Michele Trenti, called the achievement a milestone. "SpIRIT is an advanced satellite designed and constructed in Australia, with many of its components on their first-ever flights and delivering an Italian Space Agency-provided scientific instrument," Trenti explained. "Now that SpIRIT has been successfully tested in space, we think it's good to go for the next stage of its mission, which is a real thrill.".

Detecting gamma-ray bursts, rare outbursts of high-energy light that burst forth when stars disintegrate or crash, is at the heart of SpIRIT's quest. Such blasts are unpredictable and extremely luminous, briefly shining brighter than entire galaxies at times. Since they last only brief seconds, finding one in progress can be looking for a needle in a haystack.

SpIRIT would be an early warning facility component, alerting astronomers on such an occurrence. Operating together with other satellites and ground-based observatories, it would allow scientists to act quickly to study these astrophysical outbursts before they vanish.

In its first real test, the HERMES detector learned on the Crab gamma pulsar, a well-known cosmic beacon, and found its signal in just 700 seconds of exposure. That achievement certified the instrument and demonstrated that it could return valuable data.

Beyond its scientific potential, SpIRIT has already shown some pizzazz. As part of its first deployment, the spacecraft ejected its specially designed winged thermal management system built by the University of Melbourne. The wings are for temperature control and to boost science performance.

With them, a small "selfie stick" extended to capture an image of the nanosatellite in space, adorned with the badges of the international partners that made the mission possible. When completely unfurled, the satellite is nearly a meter wide.

Australian Space Agency chief Enrico Palermo congratulated the achievement. "The SpIRIT mission has demonstrated the potential within the Australian space sector – from building the satellite and testing new technologies in orbit and on the ground, to hosting international science payloads and successfully concluding its first phase," he stated.

International cooperation is at the heart of the mission. Teodoro Valente, president of Italian Space Agency, said the mission is a reflection of technological excellence and strategic value of cooperation. "The SpIRIT satellite carries on board a prototype detector sponsored by ASI, designed entirely in Italy under the technical guidance of INAF," Valente said. "The nominal operation of this reduced-size instrument…has been demonstrated by pointing toward the Crab gamma pulsar."

By combining Australian creativity with Italian machinery, SpIRIT demonstrates how nations can share their abilities to chart the universe better than they can do alone.

The SpIRIT mission demonstrates that inexpensive, small satellites can achieve great scientific goals. If successful, its fleet-based approach to viewing space could transform how astronomers track violent cosmic events. Instead of depending on vast, expensive observatories, researchers might one day rely on networks of small satellites working together.

That shift might make it possible to receive faster alerts of gamma-ray bursts, allowing astronomers to capture precious data on black holes, neutron star mergers, and expiring superstars.

For Australia, the mission consolidates its growing reputation as a valued player in global space exploration. To people, it offers a new way of witnessing the universe's most violent occurrences happening in real-time.

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