We leave daylight behind as we descend the stairs into a long dimly lit corridor, lined with pipes, wires and ventilation ducts. Our footsteps echo on the concrete floor as aging fluorescent tubes flicker above us. Eventually, about midway down, we find the unmarked door we’re looking for. Here, in the unlikely surroundings of a windowless basement laboratory at Nasa Ames in California, a revolutionary spacecraft is taking shape.
Cornell University graduate student Zac Manchester has been lent this lab to develop KickSat. This 30cm- (12in-) long satellite will contain 200 even smaller satellites, he’s called sprites. Around the size of a couple of postage stamps, these are probably the smallest spacecraft ever developed.
Not only is the design of this space project unique but also the way it is being funded. Money for KickSat has been raised through the crowd-funding website Kickstarter and the sprites are allocated to the project’s supporters. Last year, BBC Future and the Space Boffins podcast paid the $300 on your behalf and I have travelled to meet Manchester to see what we are getting for our investment.
“I’d like to think of it as the people’s satellite,” says Manchester. “We’re pushing towards a personal satellite, where you can afford to put your own thing in space.”
The sprites look more circuit board than satellite but despite being just 3.5 cm (1.5in) square and only a few millimetres thick, they are packed with technology. “Half the board is taken up with a solar array, then there’s a microcontroller – like a little computer,” Manchester explains, holding one of the sprites carefully between his finger and thumb. “Then we have a radio transceiver and two sensors – a magnetometer and a gyroscope.” These instruments enable the devices to sense the Earth’s magnetic field and take readings of orientation and spin. “We want to see how these come out of the mother ship, KickSat, and how they’re spinning after that.”
Memory metal
This KickSat mother ship is made up of three 10 cm (4in) cubed units, known as Cubesats. One of these sections will contain the control systems for the spacecraft and the remaining two will carry the sprites. KickSat is designed to be launched as a “piggyback” payload alongside another satellite and, once released into orbit, the sprites will be ejected.
Manchester has used a 3D printer to create a full-sized copy of KickSat to demonstrate how it works. It looks a bit like a shoebox with a door at the end. “There’s a plunger mechanism that holds the 200 sprites in place,” he says. “When we trigger the deployment from the ground station, we’ll release the spring and the whole thing will pop out releasing the sprites into space.” He tips the box and mock-up plastic sprites scatter across the floor.
Unfortunately, it’s not quite that simple. As the sprites are solar powered, for them to function correctly, it is essential that when they are released they are pointing at the Sun. To achieve this, KickSat will be orientated towards the Sun before being spun around its axis, to allow centripetal force to propel the sprites away from each other as they spew out into space.
So they can radio back to Earth, it is also crucial that the antennas deploy correctly. These are made Nitinol or memory-metal – thin strands of wire that always revert to their original shape. These whiskers of metal will be coiled up tight within KickSat and spring out when they are released.
