SpaceX Engineers Answer Questions About Starlink During Reddit 'Ask Me Anything' Session

Featured Image Source: Starlink Satellite Render By @ErcXspace via Twitter

SpaceX engineers participated in a Reddit ‘Ask Me Anything’ (AMA) session this afternoon. Space enthusiasts had the opportunity to ask written technical questions via the online platform related to the aerospace company’s rockets, spacecraft, software, and SpaceX’s broadband network. “We're a few of the people on SpaceX’s software team, and on Saturday, May 15 at 12:00 p.m. PT we’ll be here to answer your questions about some of the fun projects we’ve worked on this past year […]” they said. SpaceX has achieved a lot of incredible things this past year including: launching their first set of crewed missions with Crew Dragon to the International Space Station under NASA’s Commercial Crew Program, as well as rapidly developing the next-generation spacecraft, Starship; and rolling out Starlink beta internet service to the U.S. and abroad. The company already operates the world’s largest broadband constellation with approximately 1,624 satellites in orbit.

“It's cool to see as many women on this list as there are, especially in lead positions,” a Reddit user wrote in reference to the female engineers participating in the AMA session, “How does the SpaceX work environment vary from other places you've worked? What things would you do to encourage young girls/women that are interested in coding and/or space?” they asked. “I love the SpaceX environment because we get to work on the most challenging problems and change the world,” SpaceX Engineer Kristine Huang, who leads application software for Starlink constellation, wrote in response. “I encourage young girls and women to dream big, follow your passion, and believe in yourself. When the journey gets challenging, that means you're in the right place so that you can grow. It’s never too late to learn software engineering,” she said, “Software engineering is about being logical, thinking critically, and also being creative – if that appeals to you, you can be a software engineer.”

SpaceX engineers answered many questions about the Starlink network. Huang discussed the subject of making the Starlink dish antenna and equipment manufacturing ‘more scalable.’ “For the production scale we're looking to achieve with Starlink kits, we've been building from the ground up for much of what we're doing here, growing into a new factory with new software systems that have been designed with Starlink's planned scale in mind,” she wrote. The company's Starlink manufacturing headquarters are in Redmond, Washington State, and they have plans to open a new manufacturing facility in Austin, Texas. “The software team is colocated in the factory with everyone else that is thinking about this problem, and they have spent time building Starlinks on the line to ensure they've understood the high rate manufacturing processes as well as they can. For a factory producing at our desired target rate we're looking to have a highly integrated factory system, with automation, robots, people, and software working together. The guiding principle is generally to keep looking for how much we can simplify what we're doing,” Huang shared.

SpaceX founder Elon Musk aims to make the Starlink internet infrastructure mobile before this year ends, so customers are able to take their phased-array dish antenna anywhere they go aboard vessels at sea, RV’s, large trucks, even aircraft. A Reddit user asked about what kind of work engineers are doing to convert Starlink into a network capable of serving customers on-the-go. “The biggest challenge we have to solve when thinking about fixed ground terminals is how to allocate "beams" from satellites to each spot on Earth we want to serve,” Huang said, “We have to take into account how many users need bandwidth, radio interference from other satellites (including ourselves!), and field of view constraints. Motion does not generally add much complexity for the telemetry system. It does present some interesting challenges when it comes to satellites for example which are out of contact from the ground in parts of their orbit. This means our telemetry system has to be resilient to out of order and/or late arriving telemetry,” she explained, “Moving targets require us to solve the attitude determination problem (which way is dishy pointing?) quickly and continuously. They also change the number of users are in a given spot at once, which affects how much bandwidth is needed there.”

A Starlink internet beta user said -“The transition between Starlink satellites is so smooth its unnoticeable. How have you guys managed to make this happen?” they asked. “The starlink system is built to be super dynamic since our satellites are moving so fast (>7km/s) that a user isn't connected to the same satellite for more than a few minutes,” SpaceX Engineer Jeanette Miranda, who works in developing Starlink firmware for laser communications said. “Each user terminal can only talk to one satellite at a time, so our user to satellite links utilize electrically steered beams to instantaneously change targets from satellite to satellite, and we temporarily buffer traffic in anticipation of this ‘handover,’” she explained in the Reddit post. “Our satellite to gateway links use mechanically steered antenna, so we have to account for movement time and make sure we don't "let go" of one connection until we've securely established the next one. A good visual is to picture our satellites "walking" their gateway connections across the earth as they fly by,” she said.

Another SpaceX engineer, Natalie Morris, who leads software test infrastructure for the Starlink satellites, said that “To manage a large satellite constellation without needing hundreds of human operators, we rely on software automation running on the ground and on the satellites,” she wrote, “In order to fully test our systems in an end-to-end configuration, that means we have to integrate hundreds of different software services in a dev environment.” Morris shared that it is challenging to test the network’s capability. She shared that engineers in the Starlink team set-up ‘mock ground stations with a fixed antenna’ to test some aspects of the network. “We can run a test where we simulate the satellite flying over the ground station, but we have to override the software so that it thinks it is always in contact with our fixed antenna […].” You can read the full SpaceX engineers Reddit AMA session in the link below.

SpaceX software team will do an AMA tomorrow on @rSpaceX https://t.co/bx3gyskstW

— SpaceX (@SpaceX) May 14, 2021

Featured Image Source: Starlink Satellite Render By @ErcXspace via Twitter