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Inside the Space Drone, the orbital 'jet pack' to extend satellites' lives

Shahida Barick

The Space Drone satellite 'jet pack' (Credit: Effective Space)
The Space Drone satellite 'jet pack' (Credit: Effective Space)

Shahida Barick, head of spacecraft operations at Effective Space, explains how the Space Drone will extend the life of other satellites

Unconventional satellite

The Space Drone is very different from a conventional satellite in geostationary orbit. It weighs 400kg – more than a CubeSat, but still small for a satellite. It has some obvious features such as the solar arrays and a conventional spacecraft body. An antenna boom is away from the main structure to make sure our telecommands get through.

Autonomous rendezvous 

Once it ejects from the launch vehicle, it begins a rendezvous sequence when 2km from the customer, the host spacecraft.

 A lidar sensor identifies the host, and a camera switches on at 50m. The lidar and camera data is amalgamated, allowing us to identify the launcher interface ring on the host spacecraft. An attitude sensor – a Sun-tracker that monitors alignment – combines with the other data to precisely align with the host. 

The sequence is autonomous but there are a number of ‘hold points’ where it stops before being told to continue by satellite control.

Floats like a butterfly

When we reach the customer spacecraft, our docking arms latch onto its launcher interface ring, a very robust component that attached to the original rocket that launched it into space. The part’s strength means it can absorb the docking torques.

The docking should be soft, because if it isn’t we’ll generate disturbance torques that could disrupt the attitude and orbit. 

It’s a subtle process, like a butterfly closing its wings.

Becoming a jet pack

Following the docking, a ‘joint stack’ is established. The customer spacecraft powers down its actuators and thrusters, because two satellites docked to each other can’t have two control rooms – they would fight against each other and it could jeopardise their integrity.

We essentially become a jet pack, taking over the attitude and orbit function. The dedicated electric thrusters will fire when needed to ‘station-keep’, maintaining the fuel-free customer’s position in its orbital slot. 

We use xenon gas for propulsion, and the solar panels provide power to all the subsystems when in sunlight. A battery provides power to the spacecraft in eclipse.

Satellite life extension

We will deal with much bigger spacecraft – our first contract award, announced earlier this year, is for us to dock to a satellite that is over two tonnes.

Because our spacecraft is so small in relation, it makes it so much easier to dock and the centre of gravity doesn’t move that much.

By keeping customer spacecraft in their orbital slot they can continue providing accurate information to Earth, potentially for an extra 15 years.


Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.
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