Testing satellites with friction-free 3DOF spherical air bearings
GlobalSpec News Desk | September 09, 2024The number of active satellites in space keeps growing at an accelerated pace. In July, Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, estimated that there are more than 10,000 active satellites orbiting our planet already. Different estimations expect that number to grow by several 10,000s possible up to 100,000 by the end of the decade.
With the advent of compact CubeSats and commercial spaceflight, the cost of building and transporting a satellite into space has dropped significantly, which has made feasible the use of a global network of low Earth orbit (LEO) satellites for free space optical communication via laser beams.
This emerging technology has a huge potential for rapid growth and the increased demand for satellites also drives the need to new test equipment. Commercial and academic institutions developing these satellites continuously work on improved test systems and methodologies to fully validate their hardware before launch.
PI’s 3-DOF spherical air bearing systems are commonly used to test the attitude control systems of small satellites. The frictionless nature of the spherical air bearing makes it easy to simulate a zero-gravity environment, allowing the satellite’s pitch, roll and yaw control systems to function as they would in space without cumbersome and expensive test simulations, such as traditional drop testing.
PI’s A-651 – A-657 series of spherical air bearings offer frictionless motion in three rotary degrees of freedom – with unrestrained rotation about the vertical Z-axis and +/-45° tilt motion about the horizontal X and Y axes. They are available with diameters from 50 mm to 300 mm and can carry payloads from less than 20 lbs up to 1,400 lbs with compressed air at 80 psi.
This variety in size provides solutions for nearly any small satellite, from 1U picosatellites to half-ton minisatellites. The moving element of the PIglide HB spherical air bearing is lightweight to reduce moving mass and moment of inertia, ensuring the test system closely simulates actual satellite behavior.
What is attitude control and zero-gravity simulation testing?
Attitude control testing: Spherical air bearings are extensively used for testing the attitude control systems of satellites. They provide a frictionless environment that allows for the simulation of pitch, roll and yaw movements, which are essential for assessing how a satellite will orient itself in space.
Zero-gravity simulation: These bearings simulate a zero-gravity environment by allowing frictionless motion in three degrees of freedom (3DOF). This capability is vital for testing how satellites will behave in the weightlessness of space without the need for expensive and complex drop tests or parabolic flights.
Most of the small satellites will be used in free space optical communication, promising affordable high-speed internet at any place on the planet.
In addition to the spherical air bearings, PI also provides other solutions for space applications, such as 6DOF hexapod positioning systems that can be used in the validation of optical terminals, such as the OTVT at the MIT Lincoln Laboratory and fast steering mirrors for free space optical communication in LEO satellites.