SpaceX To Conduct More Airborne Starlink Connectivity Tests For Air Force Research
As it continues to generate investor funds and launch payloads to low earth orbit (LEO) and the International Space Station (ISS), launch service provider and equipment manufacturer SpaceX is also busy moving forward with its satellite-based internet service dubbed Starlink. The service is central to SpaceX's plans for generating non-investor funds necessary for the research and development costs of the company's Starship heavy-lift launch vehicle platform which consists of the Super Heavy launch vehicle and the upper stage spacecraft also called Starship.
With Starlink, SpaceX is working with the U.S. Air Force's Ohio-based research arm for establishing connectivity with ground sites, aircraft, between satellites and from space to aircraft without the need for ground stations. The company was awarded the deal (FA8650-19-9-9320) worth roughly $29 million in 2018, and the Air Force expects testing to be finished by mid-June next year.
For these purposes, the FCC granted SpaceX the authority in July (File Number: 0430-EX-CN-2020) to conduct more Starlink experiments testing connectivity from both ground-based sites and from antennas located on aircraft to the satellites. Following this grant, the company has kicked off the process by requesting authority for conducting these experiments in Colorado.
SpaceX Hopes To Conduct Experiments From September This Year
SpaceX filed the request (1149-EX-ST-2020) with the Commission for the experiments at the end of July, with the company requesting the regulatory body to grant it a six-month window starting in September, to use one antenna to broadcast frequencies in the 14-14.5 GHz, 27.95-29.1 GHz and 29.5-30 GHz bands. Out of the three bands, the antennas that will be fixed on aircraft will use the 14 GHz Ku spectrum, and the filing does not add details about which ground-based stations will be part of the experiments.
SpaceX's plans for the test simply involve using antennas utilizing some similar technical parameters as its future user terminals for Starlink and placing these antennas on an airborne aircraft. However, as the latest filing with the FCC reveals, the company has continued to tweak the antenna design to increase output power over the years.
As part of its experiments with the Air Force, SpaceX plans to use a total of twenty antennas. Out of these, 18 have been manufactured in-house by the company, and two have been manufactured by Colorado-based aerospace technologies firm Ball Aerospace. Given the location for SpaceX's latest request, it's likely that the two companies are testing out upgrades to Ball's antennas that have been used in earlier Starlink experiments conducted with the constellation's first two prototypes, the Microsats 2a and 2b.
SpaceX's narrative for the DEUCSI program that covers these experiments reveals that the company will keep several aircraft-related parameters in mind when conducting them. It will conduct tests with static angles that range between zero to 70 degrees, and prior to integrating the antennas on the test vehicle, the company will ensure that the equipment is compatible with the aircraft's pitch and roll motions. A pitch describes the upward or downward movement of an aircraft's nose while a roll describes its clockwise or counterclockwise movement.
To place the Ball Aerospace antennas onto the vehicle, SpaceX will develop mechanical plates for installation and a fairing to protect the equipment against drag. In astronautics and aerospace, a fairing is used to refer to an encapsulation unit for a payload, whether an antenna or a satellite and the one being designed by SpaceX for this experiment will also serve the purpose of protecting the aircraft from any impact from the antenna itself.
The FCC granted SpaceX authority to conduct the tests in mid-July for a filing filed in May, and the company's request for the Colorado test was filed just days before NASA astronauts Robert Behnken and Douglas Hurley returned from the International Space Station (ISS) on SpaceX's Crew Dragon spacecraft.
Technical specifications part of the May filing reveal that the aircraft antenna for the tests will have slightly higher power output than earlier versions. The newer variants have greater half-power bandwidths (HPBW), which are defined as the part of their output with the greatest consistency. The variants also more powerful than the ones SpaceX had listed for testing in an earlier FCC application (0515-EX-CN-2019), but key performance parameters such as gain are unchanged.
This, combined with the fact that all filings refer to the same product model number confirm that so far, the testing equipment has not achieved a generation upgrade and that the changes are likely to be in response to data gathered from earlier tests.