SAN FRANCISCO — NASA has approved a demonstration flight for DiskSat, the thin round satellite designed by Aerospace Corp.
Aerospace Corp. engineers are building four DiskSats and a DiskSat Distributor, which they plan to send to low Earth orbit in 2024 to validate the technology.
“People ask me, ‘Can you really fly this? Can you keep it under attitude control? » SpaceNews. “It’s a very unsightly vehicle compared to other things that are traditionally driven. Can you do the thermal management so you don’t melt away harvesting all that solar energy?”
The one-meter-diameter DiskSats are 2.5 centimeters thick. With the vast surface area of the solar panels, DiskSats could provide around 60-80 watts for the on-board electronics. A DiskSat with a rigid deployable solar panel provides an average onboard power of 100 to 160 watts.
Much of the power is likely to be harnessed for propulsion. During the demonstration mission, Aerospace plans to fly DiskSats into very low Earth orbit.
A pair of DiskSats, deployed from a rocket at an altitude of around 500 kilometers, will maneuver into an orbit of 250 kilometers. With propulsion to combat drag, mission planners intend to keep the DiskSats at this altitude for more than a week before moving them to a higher orbit.
The second pair of DiskSats will fly in an eccentric orbit with a perigee of less than 200 kilometers.
“The propulsion system has enough thrust to offset drag out to about 230 kilometers in a circular orbit,” Welle said. “But in elliptical orbit you can descend lower provided you have time at a higher altitude to do the drag makeup.”
At the end of April, Aerospace launched the 18-month development campaign for the DiskSat demonstration mission. No launcher has yet been identified.
At the Small Satellite Conference at Utah State University in August, Aerospace plans to showcase a DiskSat model.
“We’ll be happy to talk to anyone interested in flying a DiskSat,” Welle said. “We plan to develop a DiskSat standard, analogous to the cubesat standard. We will define the interface between the satellite and the launcher with the idea that it can be used in carpooling operations.
Aerospace engineers develop a dispenser to release the circular spacecraft.
“Long term, you can have flights with 20 DiskSats in a single dispenser,” Welle said. “We are developing a distribution mechanism that will release them one at a time with a reasonable delay in between to ensure separation between adjacent drives in the stack.”
Welle sees the main advantages of circular DiskSats over cubesats.
In terms of power, an eight kilogram DiskSat with a deployable panel can easily deliver 100 watts of average onboard power. To deliver the same power, a cubesat with deployable panels would weigh around 30 kilograms, Welle said.
With more power and less mass than cubesats, DiskSats could use electric propulsion to drastically alter their orbits. A 10 kilogram DiskSat could move, for example, from low Earth to geosynchronous or even lunar orbit.
Additionally, the 2.5 centimeter edge of a DiskSat would encounter little atmospheric drag, which is why miniature satellites could operate at low altitudes. There is growing interest in very low orbits where sensors can collect high-resolution images of the Earth.
“Operating DiskSats within 300 kilometers is simple,” Welle said. “It gives you a whole new orbital regime that isn’t overpopulated by other satellites.”
DiskSats are lightweight composite structures with hollow interiors. Components can be distributed throughout the internal volume or grouped together in a central avionics bay.
“There’s a lot of volume that’s spread out and easily accessible,” Welle said. “It greatly simplifies the manufacturing process.”
Additionally, DiskSats in low Earth orbit are likely to re-enter the Earth’s atmosphere quickly after completing their missions. Without attitude control, a DiskSat orbiting 600 kilometers will re-enter the atmosphere for about two and a half years.
“If the attitude control system goes down, the satellite goes down,” Welle said. “It will increase drag by an order of magnitude.”