SpaceX ready for 60-satellite Starlink launch debut: third time’s the charm?

SpaceX is approximately two hours away from its third Starlink v0.9 launch attempt, an ambitious batch of 60 satellites that will also be the company’s heaviest payload ever.

As hinted at by the name “Starlink v0.9”, these sixty satellites are not quite the final design. More a beta test at an unprecedented scale, several critical new technologies and strategies will be put to the test on this launch, ranging from a seriously unorthodox satellite deployment method to the near-final krypton-fueled electric thrusters. Same as SpaceX’s May 15th and 16th launch attempts, Starlink v0.9’s third try has a 90-minute window that opens at 10:30 pm EDT (02:30 UTC), this time on Thursday, May 23rd.

Falcon 9 and 60 Starlink satellites are vertical on Pad 40. Launch window opens tonight at 10:30 p.m. EDT → https://t.co/gtC39uBC7z pic.twitter.com/166LTfD68M

— SpaceX (@SpaceX) May 23, 2019

Third try’s the charm

May 23rd’s Starlink v0.9 launch attempt will be the mission’s third, preceded by May 15th – scrubbed by high-altitude wind shear – and May 16th, cancelled before fueling began in order to troubleshoot and update the software aboard the 60 Starlink satellites. After a week of concerted effort from SpaceX technicians and software developers, those issues have been more or less dealt with and the first batch of Starlink satellites are once again ready for orbit.

According to SpaceX, the massive payload of 60 flat-packed Starlink satellites weighs approximately 18.5 tons (16,800-18,500 kg, unclear if short or metric tons). Either way, it will easily break SpaceX’s previous record – likely Crew Dragon’s DM-1 debut – and become the heaviest payload the company has ever attempted to launch. Despite the sheer size and mass of the payload, Falcon 9 booster B1049 – launching for the third time – will still be able to land aboard drone ship Of Course I Still Love You (OCISLY) some eight minutes after launch.

If the recovery goes well, B1049 will become the third SpaceX booster to successfully complete three orbital-class launches and landings, paving the way for a series of fourth flights (and beyond) later this year.

Cubesats, meet Flatsats

Aside from the mission’s impressive rocket performance requirements, Starlink v0.9 will also serve as a huge beta test of a dozen or more new technologies. The most visible of those has to be each satellite’s truly unique flat, rectangular form factor, as well as SpaceX’s use of flat-packing in place of a dedicated structure for holding and dispensing the satellites. It’s unclear if there is some additional reinforcement or if the satellites themselves provide all of the stack’s strength. If the latter is true, the satellites at the bottom must survive massive forces – ranging from ~7000 kg at rest to 35,000+ kg at the end of Falcon 9’s second stage burn.

Aside from their exotic structure, each Starlink satellite also carries a single-panel ~3 kW solar array using one of two experimental deployment mechanisms. Each satellite’s main propulsion comes from an unknown number of Hall Effect thrusters (i.e. electric/ion thrusters) fueled by krypton instead of the usual xenon. SpaceX’s internally-developed krypton thrusters are the only known examples to have been tested in orbit.

Elon: We have the most advanced phased array antenna that I am aware of. #SpaceX #Starlink

— Michael Baylor (@nextspaceflight) May 15, 2019

Aside from thrusters, SpaceX CEO Elon Musk also believes that the company’s space-based phased array antennas – also developed in-house – are more advanced than any operational competitor on Earth. Musk also revealed that SpaceX would attempt to use a bizarre and largely untested method of satellite deployment, spinning Falcon 9’s upper stage and releasing the satellites with inertia instead of traditional springs or pushrods.

Regardless of whether everything works as planned, the launch is going to be a spectacular one and the webcast may even include views of the bizarre satellite deployment. Catch SpaceX’s live coverage of the mission – likely to include new details about the Starlink constellation – at the link below. Coverage will begin ~15 minutes prior to liftoff.

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Source: https://www.teslarati.com/spacex-60-satellite-starlink-launch-third-try/