The UK’s CarbSar to feature a knitted radar antenna

22nd May 2023
The UK’s CarbSar to feature a knitted radar antenna

Two UK based development companies are designing a satellite that will provide precise images of the Earth, day and night – even during cloudy days that may obstruct the vision of other satellites. And, to make things even more interesting: part of the satellite will be constructed – or knitted – by an industrial knitting machine.

The satellite is called CarbSar. It’s an innovative and low-cost radar satellite designed to plug the hole in the UK’s security woes. CarbSar will provide images of the Earth during night and even in cloudy areas.

How does CarbSar work?

CarbSar will open like an umbrella once in the Earth’s lower orbit: Credit: OSS

CarbSar is being developed by UK based Oxford Space Systems (OSS) and Surrey Satellite Technology Limited (SSTL). The two companies have been working to proactively provide an answer to the UK’s satellite-borne security issues.

So, how does it work? Well, the CarbSar is a radar satellite that features a knitted tungsten wire mesh dish that will be folded during the launch. Once the CarbSar reaches the Earth’s orbit, the mesh will fling out like a coiled spring into an umbrella shape; then the radar unit, with its 3m wide reflector, will be able to start taking pictures of the Earth unobstructed.

Its revolutionary picture techniques

By using Side Aperature Radart technology, the satellite can take images of the Earth unobstructed by weather events and clouds; it can even take images during night. SSLT launched an SAR satellite in 2019, but the new antenna that’s in the works the new version will be able to resolve images of objects less than a metre wide. 

A knitted satellite?

One unique feature of the satellite’s construction is that the reflector ispartially knitted by an industrial knitting machine Yarns of the gold-plated knitted tungsten wire mesh – which is nearly invisible – will be fed into an industrial knitting machine to build the umbrella structure.

Testing is currently underway, and OSS has been using a large rig to repeatedly stow and deploy the antenna to test that the spring-like mechanism will pop open on command. The work has been evenly spread: OSS is currently working on the deployable antenna/reflector and SSTL are contributing by completing the bulk of the work, such as the internal driving systems and the intrinsic electronics.

How will the satellite spring into action?

The mesh is connected to a series of carbon-composite rods that can be wound up into the antenna’s nucleus hub. However, the idea that OSS and SSTL have explored is how the satellite will spring into action – quite literally. 

When designing the umbrella-like antenna, the team developed a spring-like motion that will branch outwards due to the strained energy in the rods that will want to jump back into their natural straightened configuration. This will then pull the mesh into place allowing the satellite to get to work in providing crystal clear images.

Company CEO Sean Sutcliffe told BBC News in an interview that: “You need it to be as simple as possible because the more parts you have the more chance there is for something to go wrong. It’s also got to work every time, so you need to make sure it has enough strain energy to know that it’s definitely going to come out fully – that it won’t stall half way through. But then you also don’t want the system to have so much energy that it tears itself apart or damages the satellite.”

The UK government and CarbSar

The UK government is working with both OSS and SSTL on the project: Credit – SSTL

The UK government has taken a keen interest in the SAR technology, including the antenna, that CarbSar sports. The broad-scale Russian invasion of Ukraine has signalled a need for stronger Earth Observation capabilities, and with natural phenomena like flooding and wildfires becoming more frequent due to the climate crisis, the CarbSar has never been more crucial. Therefore, the UK government is supporting CarbSar’s development and further contributions are coming from the National Security Strategic Investment Fund.  

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