Farlington, Portsmouth, UK

There are certain areas of the planet that are simply too sparsely inhabited for it to be economically viable to roll out terrestrially oriented communication infrastructure such as cellular base stations or Wi-Fi hotspots. As a result, a large portion of the Earth's population still does not have next-generation voice/data services that are already commonplace elsewhere.

Australian communications provider Sky and Space (SAS) Global is looking to change this. Rather than relying on conventional terrestrial networks, it plans to offer services through its latest nanosatellite constellation. Referred to as The Pearls, this constellation will comprise about 200 nanosatellites — located in low Earth orbit (LEO) — in orbital rings near the equator. The objective is to provide more cost-effective and affordable communication capabilities to parts of the world where it has been impractical to do so.

The multitude of nanosatellites that makes up The Pearls constellation is fitted with a 3-meter expanse of Sun-tracking photovoltaic panels through which solar energy can be acquired. Each one will be positioned into orbit evenly spaced from other nanosatellites, creating an orbital “necklace,” with communications frequencies residing in the S band (2 GHz to 4 GHz). At the same time, they will also have the capacity to communicate with one another, each satellite acting as a router.

It will take each of the nanosatellites approximately 90 minutes to circle the globe. As they continue through their orbit, they will hand over communication coverage of a particular area to the next nanosatellite in the chain (and subsequently take on the coverage responsibilities from the preceding nanosatellite). By forming an unbroken ring of nanosatellites, the narrowband wireless coverage will be maintained at all times. Via this venture, it will be possible for voice, messaging, IoT, and M2M communication services to be available without high costs.

Danish satellite specialist GomSpace, which had been involved in the test project, won a bid to develop the nanosatellites required for The Pearls constellation. Since then, its engineers have been working closely with the UK branch of SAS on defining the exact requirements of the hardware design and the key attributes of all the constituent components.

In order to minimize both the launch payload and ongoing power consumption, each of the nanosatellites will have external dimensions of no more than 24 × 45 × 12 cm. This means that all the essential electronic circuitry must be squeezed into an extremely confined space. It has been critical, from both an economic and a logistical perspective, that the nanosatellite design should, as much as possible, feature commercial off-the-shelf (COTS) components rather than rely on custom products.

GomSpace consulted Harwin on how to deal with connectivity considerations. Based on their compact size, lightweight plastic-shelled construction, and ruggedness, various models of Harwin's Gecko latched connector series were specified. These high-contact-density, narrow-pitch (1.25 mm) connectors have been employed in a host of space-related projects. Possessing resistance to shock and vibration, as well as having an operational temperature range that spans from -65 to +150 °C, they present an ultra-high-reliability interconnect solution.

Another advantage of the Gecko products is outgassing properties. These connectors perform well when placed into a vacuum (thereby safeguarding against a potential cause of faults in electronic circuitry). An initial quantity of 100 units was supplied for development and included both through-hole and surface-mount versions (in 6-pin to 34-pin formats), with more than 35 mated pairs being incorporated into every nanosatellite. More units will be needed to complete the project and meet ongoing requirements as individual nanosatellites are replaced over the course of the next decade. Production of the satellites is underway and space deployment is due to commence this year. The nanosatellites will be in place and the constellation operational within 2020.

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This article first appeared in the February, 2019 issue of Tech Briefs Magazine.

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