Danish satellite manufacturer to send the world’s first nanosatellite into geostationary orbit
Danish company Space Inventor will send a satellite into geostationary orbit around Earth this spring—with specially designed equipment that SpaceX has developed for the satellite so that it fits on the large Falcon Heavy rocket.
American satellite operator Gravity Space has ordered the satellite and will be responsible for operating it.
No one has ever sent such a small satellite that far out into space.
SpaceX and Space Inventor have had to adapt the large rocket so that it can handle the satellite, which measures 22.6 x 22.6 x 45.4 centimetres and has a payload of less than 10 kilogrammes.
The satellite will be used for telecommunications and may herald a new paradigm shift in the use of satellites.
From old to new space
Traditionally, the satellite industry has been divided between, on the one hand, the large conventional satellite companies that develop and operate large satellites in GEO and MEO, which are used for, among other things, telecommunications, satellite TV, or Earth observation, and on the other hand, the smaller and often newly established satellite TV companies that develop smaller satellites for LEO, low Earth orbit, (less than 1,000 kilometres from Earth).
But those distinctions are becoming more blurred.
“Firstly, access to space today is much more attainable, especially because of SpaceX’s regular Falcon 9 and Falcon Heavy launches. Secondly, we have shown that it is possible to deliver functional satellites with commercially available components,” says Dennis Bo Hansen, senior systems engineer and project manager at Space Inventor, which is headquartered in Aalborg.
He mentions that several commercial deployment solutions have appeared at the same time, and the two conditions mean that a satellite manufacturer like Space Inventor can focus more on developing satellites and less on launching.
Today, the number of manufacturers and operators in geostationary orbit is limited because hardware costs are traditionally high due to a different level of radiation so far out in space, and launches have typically been expensive.
But things have changed.
“Nanosats and cubesats have reached a point where it is no longer of interest to reduce their size. Now we increase the size and send the satellites further out, but according to the same principles as when we build nanosatellites for low Earth orbit,” Dennis Bo Hansen says.
While for a number of years the race has been focused on building as small satellites as possible, today it is more about building satellites with a larger payload, but without requiring specially developed hardware.
Space Inventor is a relatively new Danish satellite manufacturer, which was founded in 2015 and back then mainly developed tiny nanosatellites for universities.
Since then, they have moved from the tiny nanosatellites, 1U and 2U, and up to the largest category of nanosatellites, 16U.
“Our goal is to move further up in size. We would like to position ourselves in the market for satellites that have a payload of between 20 and 70 kilogrammes. We have a number of employees who have previously worked with larger satellites, so we have the skills internally,” Dennis Bo Hansen says.
The thing that is special about geostationary satellites in particular is that, due to a speed of approximately three kilometres per second at an altitude of almost 36,000 kilometres over the equator, they are always above the same point on Earth’s surface.
The combination of speed and altitude means that the satellite appears to be completely stationary in relation to Earth, and therefore one can point, for example, an antenna directly towards it.
In addition to telecommunications, smaller geostationary satellites are suitable for military surveillance tasks.
Although their capacity does not match the capacity of large geostationary satellites, the delivery time for them is radically lower.
The time from an order being placed to the satellite being in orbit can now be reduced to one to two years.
“We can do that because we work with modules that we produce in larger batches and which are then put together as needed,” Dennis Bo Hansen says.
Today, when small nanosatellites are launched from a rocket, it is usually done with the help of a deployer, which is a small box with a lid at one end and a spring at the other.
When the rocket reaches its planned altitude, the satellite is launched out of the box.
However, this is not the normal procedure on the Falcon Heavy, where dispenser rings are used instead to attach the satellites to the rocket.
“It’s absolutely amazing that we have been given space on the Falcon Heavy, and it has been quite a challenge to mount our small satellite on a rocket as large as the Falcon Heavy. SpaceX will use both a special mounting structure and a classic deployer; so that method is completely new to us, SpaceX, and the future operator of the satellite. It’s great to be able to challenge SpaceX when it comes to launching satellites,” says Astrid Kjeldal, sales manager at Space Inventor.
The plan is for the satellite to be sent up to an altitude of 35,000 kilometres, where it will be released.
From here, it must find its own way the last 1,000 kilometres to geostationary orbit, where it has to find the assigned position. This is done with the help of four small ion thrusters.
“We expect the last part of the journey to take a few months. In addition to raising the pitch, we have to coordinate the journey so that we glide into the right position at the last moment,” Dennis Bo Hansen says.
When the satellite is in place above the equator, the signals will be received on Earth with the help of the Swedish Space Corporation, which already has a network of large ground stations.
The satellite will be sent up next to the new, large, six-tonne Viasat-3 satellite.
Space Inventor is not able to disclose who their nanosatellite is being developed for, other than that it will be part of a North American commercial satellite constellation.
The major technical challenge in sending a nanosatellite into geostationary orbit is designing and constructing a system that works according to the same principles as a large conventional geostationary satellite, which typically has a payload of several tonnes.
“We basically had to develop a miniature version of a geostationary satellite. We have spent a lot of time on finding the right horn antennas. On the one hand, they must be extremely small, but they also have to be able to be used according to the same principles as in large telecommunications satellites in geostationary orbit,” Dennis Bo Hansen says.
The large geostationary satellites typically transmit over the Ku- and Ka-bands at frequencies of 12–18 GHz and 26.5–40 GHz respectively. Each individual satellite squeezes many TV channels into a very small frequency range, which places severe demands on the signal-to-noise ratio.
“Since our satellite does not have to distribute TV signals and therefore has less functional requirements for signal-to-noise ratio, we can relax the requirements for antennas. At the same time, we can compensate a little by having good and large Earth receivers with a diameter of over seven metres,” Dennis Bo Hansen says.
“Geostationary orbit slots are in high demand, so we are also obliged to remain in the assigned orbit and move out into the so-called graveyard orbit when the satellite runs out of fuel,” Dennis Bo Hansen says.
Space Inventor expects the satellite to have a lifespan of five years before it has to be sent to the space graveyard.
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