23 May 2019
SpaceX launches 60 Starlink satellites, begins constellation buildout
By Caleb Henry
WASHINGTON — SpaceX launched the first 60 satellites for an internet constellation that could ultimately number 12,000 on a Falcon 9 rocket Thursday night.
The rocket took off from Cape Canaveral, Florida at 10:30 p.m. Eastern, and deployed the satellites into a low Earth orbit a little over an hour later.
SpaceX previously planned the launch for early May, but the mission was pushed back due to knock-on delays from an earlier resupply mission to the International Space Station that had its own schedule slips. Upper-level winds delayed the Starlink launch again last week, as did additional time SpaceX elected to take for software checks on the satellites.
The 60 satellites mark the beginning of SpaceX’s deployment of a global internet megaconstellation intended to generate more revenue to fuel the company’s interplanetary ambitions.
Each Starlink satellite launched May 23 weighs roughly 227 kilograms. Collectively they are expected to deliver 1 terabit per second of usable capacity, and 2.5 to 3 terabits per second of total capacity.
SpaceX landed the booster that launched the satellites 9 minutes after liftoff on the droneship “Of Course I Still Love You,” in the Atlantic Ocean. The same Falcon 9 first stage previously launched the Telstar 18 Vantage satellite to geostationary orbit in September 2018, and 10 Iridium Next satellites to low Earth orbit this January.
SpaceX deployed the Starlink satellites collectively from the upper stage, allowing the satellites to drift off using their own inertia instead of springs or another conventional deployment mechanism. The satellites collectively weighed 13.6 metric tons, making this launch the heaviest mission for SpaceX to date.
The launch deployed the Starlink satellites into a 440-kilometer orbit. From there, the spacecraft will use Krypton-fueled electric propulsion thrusters to reach their target operational altitude of 550 kilometers.
SpaceX received approval from the U.S. Federal Communications Commission in late April to operate some of its satellites at that lower orbit instead of 1,150 kilometers as previously planned.
The lower orbit means less signal lag, and also ensures that atmospheric drag will pull satellites down in five years or less, reducing the risk of space debris from any damaged or defunct spacecraft, SpaceX said.
SpaceX CEO Elon Musk, in a call with reporters last week, said the Starlink satellites will also automatically maneuver around orbital debris by using Air Force tracking data uploaded directly to each spacecraft.
Musk said Starlink will be able to start partial service with around 400 satellites, and will reach “significant operational capability” at around 800 satellites. Once the constellation reaches 1,000 spacecraft, it will become “economically viable,” he said.
SpaceX intends to do three to seven Starlink launches this year, counting this mission, according to Gwynne Shotwell, company president and COO. The exact number depends on the success of this first mission, she said.
Musk emphasized that while SpaceX has taken significant measures to make sure the Starlink satellites work, the early spacecraft have lots of new technology and could fail.
“It’s possible that some of these satellites may not work, and in fact it’s possible that, [there’s a] small possibility that all of the satellites will not work,” he said. “But these are a great design and we’ve done everything we can to maximize probability of success.”
Some of that new technology includes propulsion systems that run on krypton instead of the typical xenon fuel. Musk said krypton proved less expensive than xenon, making it SpaceX’s preferred fuel.
SpaceX is using two different deployment mechanisms for the Starlink solar arrays — each satellite has just one solar array — which carries some risk, Musk said. There is also a risk that the onboard phased array antennas may not function as efficiently as intended, he said.
SpaceX’s first Starlink satellites are scaled down from what the company intends to fly later. Shotwell said the satellites launching in this first bulk deployment lack intersatellite links that later iterations will carry.
Musk said SpaceX plans to evolve the design of the Starlink satellites over time. Ideally, new technology will make older Starlink satellites obsolete in about five years, at which point SpaceX would deorbit them and launch new, more capable versions, he said.
SpaceX wants to use Starlink to provide internet access to people either unreached by current infrastructure or with limited options for connectivity. Musk said SpaceX will likely start commercial sales late this year or early next year.
Musk said it wouldn’t surprise him
to see SpaceX launch 1,000 to 2,000
Starlink satellites a year using its
Falcon family of launchers. The
constellation doesn’t need 12,000
satellites to constitute a win, he
said, but that would mark a “very