OneWeb vouches for high reliability of its deorbit system

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WASHINGTON — Satellite broadband startup OneWeb says no other system on its low-Earth orbit satellites will be built for higher reliability than the deorbit module it is including to prevent the creation of space debris.

“The subsystems on the spacecraft that are required to do that deorbiting operation are spec’d as the highest-reliability functions on the entire spacecraft — even above that of the revenue-generating payload,” Tim Maclay, OneWeb’s director of mission systems engineering, said July 10 during a Secure World Foundation panel discussion here. “That gives you a sense of the commitment that we’ve got to responsible operations.”

OneWeb’s first-generation constellation of 900 small satellites, the first of which are expected to launch in March on a Europeanized Soyuz rocket, have prompted concerns that the company could create catastrophic space debris situations if deorbiting went unprioritized. To assuage these concerns, OneWeb stated its intent early on to deorbit out-of-use satellites within five years, a full two decades ahead of the internationally accepted 25-year guideline. Every OneWeb satellite will also have ion electric propulsion to enable deorbiting.

Maclay said the extra mass needed to store fuel for deorbiting does not have a major impact on spacecraft costs, and that OneWeb now anticipates bringing down defunct spacecraft in an even shorter period.

“We’ve committed to five years, in reality it is probably going to be like one to two,” he said. “The operation takes a little bit longer than a year.”

Maclay said each small satellite will have redundant GPS receivers to ensure position knowledge from launch to atmospheric reentry. Global ground stations will enable telemetry, tracking, and command for constant communication with the satellites, he said. Also, because each spacecraft weighs in at 150 kilograms, Maclay said they will be easily visible by tracking systems.

Maclay said OneWeb has agreements with the U.S. Defense Department’s Joint Space Operations Center and the 18th Space Control Squadron at Vandenberg Air Force Base in California for sharing spacecraft position information. OneWeb is willing to share that so-called ephemeris data with other operators as well, he said.

“It’s in everybody’s best interest to know where everybody else is,” he said. “We will do that directly, and we are also investigating value-added outlets like the Space Data Center and ComSpoc.”

The Space Data Association (SDA), a collective of mostly satellite operators and agencies, along with a handful of other satellite companies, shares ephemeris data among its members to prevent collisions, radiofrequency interference and to minimize the frequency false alarms triggered when satellites appear to be on a collision course with other satellites or orbital debris. ComSpOC, or the Commercial Space Operations Center, is operated by  Analytical Graphics Inc. to provide space situational awareness data.

Maclay said OneWeb does not intend to passivate, or deplete, the batteries on the OneWeb satellites because the company intends to guide the satellites throughout reentry. This will enable collision-avoidance maneuvers post-decommissioning, and ensure the satellites are destroyed in the atmosphere.

Maclay added that if, despite these efforts, some satellites fail to deorbit, that the company is willing to use Active Debris Removal, or ADR services — assuming such services come to market.

“If there does come a time when ADR services are commercially viable, we would like to take some steps upfront to facilitate our use of those,” he said.

How much OneWeb would be willing to pay for ADR services is hard to know, he said, because each of its satellites is expected to cost less than $1 million to produce.