After delays, Falcon 9 rocket back on launch pad with Starlink satellites

SpaceX’s Falcon 9 rocket stands vertical on pad 39A on Thursday morning. Credit: Spaceflight Now

After a six-week delay for undisclosed reasons, SpaceX raised a Falcon 9 vertical on its launch pad Thursday at the Kennedy Space Center in Florida for another try early Friday to send into orbit the company’s next batch of Starlink Internet relay stations and a pair of commercial BlackSky Earth-imaging microsatellites.

The 229-foot-tall (70-meter) launcher is set for takeoff at 1:12:05 a.m. EDT (0512:05 GMT) Friday from pad 39A at the Kennedy Space Center with 57 more Starlink satellites.

It will be SpaceX’s first launch to carry a full set of Starlink satellites equipped with new sunshades, or visors, in an attempt to make the spacecraft less visible to ground-based telescopes, addressing concerns voiced by astronomers that thousands of Starlink satellites could interfere with scientific observations.

“All Starlink satellites on this flight are equipped with a deployable visor to block sunlight from hitting the brightest spots of the spacecraft — a measure SpaceX has taken as part of our work with leading astronomical groups to mitigate satellite reflectivity,” SpaceX says on its website.

Two commercial Earth observation satellites from BlackSky will accompany the Starlink payloads into orbit, taking advantage of SpaceX’s rideshare service, which sells excess capacity on Falcon 9 missions to other companies.

The mission set for launch Friday was originally supposed to take off in late June, but SpaceX has delayed the flight multiple times. The company has not disclosed any details about the nature of the problems — other than weather — that have delayed the Starlink/BlackSky mission.

The Starlink/BlackSky launch was supposed to take off June 26, but SpaceX delayed the mission to conduct additional pre-launch checkouts, the company said on Twitter. A launch attempt July 8 was scrubbed minutes before liftoff by poor weather.

SpaceX called off another launch attempt July 11, and the company again said officials made the decision “to allow more time for checkouts,” without providing further details.

The concerns that delayed the Starlink/BlackSky launch have not affected other SpaceX missions.

SpaceX successfully launched two Falcon 9 rockets June 30 and July 20 from Cape Canaveral with a U.S. military GPS navigation satellite and the Anasis 2 military communications satellite for South Korea.

The Starlink/BlackSky launch was tentatively planned to launch last week from the Kennedy Space Center, but there were range safety concerns about the Falcon 9 rocket taking off from a pad near where NASA’s Perseverance rover — with a nuclear power generator on-board — was being readied for takeoff.

SpaceX says the Falcon 9 rocket poised for launch Friday will be powered by a kerosene-fueled first stage booster that previously flew on four missions, beginning with the launch of the company’s Crew Dragon spaceship on its first unpiloted test flight to the International Space Station on March 2, 2019.

Since then, the reusable first stage booster — designated B1051 — launched and landed successfully on missions June 12, 2019, and Jan. 29 and April 22 of this year. This will be the fifth flight of this particular first stage booster.

The launch early Friday will be the 90th flight of a Falcon 9 rocket since 2010, and the 13th launch by SpaceX so far this year.

A Falcon 9 first stage booster lands on SpaceX’s drone ship Jan. 29 in the Atlantic Ocean following a previous Starlink launch. The same booster will launch again on Friday’s mission. Credit: SpaceX

SpaceX’s launch team will ready the rocket for loading of super-chilled, densified propellants Thursday night, before the start of the countdown’s automated sequencer at 12:37 a.m. EDT (0437 GMT).

At that time, kerosene and liquid oxygen will begin pumping aboard the Falcon 9 rocket’s first stage, and kerosene will start flowing into the rocket’s second stage. At 12:56 a.m. EDT (0456 GMT), SpaceX will start filling the second stage with its liquid oxygen supply.

In the final 10 minutes of the countdown, the Falcon 9 will begin chilling its engine plumbing for ignition, activate and check out its hydraulic systems, and pressurize its cryogenic propellant tanks for flight.

Nine Merlin 1D engines will flash to life at the base of the Falcon 9 rocket, and hold-down clamps will open to allow the launcher to fly away from pad 39A at 1:12 a.m. EDT (0512 GMT).

Heading northeast over the Atlantic Ocean, the Falcon 9 will surpass the speed of sound before shutting down its first stage engines at T+plus 2 minutes, 32 seconds. Four seconds later, the booster will separate to begin a controlled descent toward SpaceX’s drone ship “Of Course I Still Love You” parked in the Atlantic Ocean nearly 400 miles (about 630 kilometers) downrange from Cape Canaveral.

The booster will target a propulsive landing on the floating platform nearly eight-and-a-half minutes into the mission.

Meanwhile, the Falcon 9’s second stage will ignite its single powerful Merlin 1D engine at T+plus 2 minutes, 44 seconds, to drive the 57 Starlink satellites and two BlackSky payloads into a preliminary orbit.

The second stage engine will shut down at T+plus 8 minutes, 51 seconds, to begin a coast halfway around the world before reigniting for a few seconds at T+plus 47 minutes, 18 seconds.

That will inject the Starlink and BlackSky satellites into a near-circular orbit ranging in altitude between 241 miles (388 kilometers) and 249 miles (401 kilometers) above Earth, with an inclination of 53 degrees to the equator.

The two BlackSky satellites will deploy from the top of the stack of Starlink satellites 61 and 66 minutes after liftoff.

BlackSky, based in Seattle, is deploying a fleet of Earth observation satellites designed to monitor changes across Earth’s surface, feeding near real-time geospatial intelligence data to governments and corporate clients. The two 121-pound (55-kilogram) satellites on Friday’s mission will become the fifth and sixth operational spacecraft in BlackSky’s fleet, which the company could eventually number more than 50 satellites, depending on customer demand.

The deployment of the BlackSky payloads will set the stage for separation of the 57 Starlink spacecraft at T+plus 1 hour, 33 minutes, or at 2:45 a.m. EDT (0645 GMT).

SpaceX’s Starlink network is designed to provide low-latency, high-speed Internet service around the world. SpaceX has launched 538 flat-panel Starlink spacecraft since beginning full-scale deployment of the orbital network in May 2019, making the company the owner of the world’s largest fleet of satellites.

With Friday’s launch, SpaceX will have delivered 595 Starlink satellites to orbit since May 2019.

SpaceX plans to debut a new sunshade structure on its future Starlink satellites. Credit: SpaceX

Each of the flat-panel satellites weighs about a quarter-ton, and are built by SpaceX in Redmond, Washington. Once in orbit, they will deploy solar panels to begin producing electricity, then activate their krypton ion thrusters to raise their altitude to around 341 miles, or 550 kilometers.

SpaceX says it needs 24 launches to provide Starlink Internet coverage over nearly all of the populated world, and 12 launches could enable coverage of higher latitude regions, such as Canada and the northern United States.

The launch Friday will be the 10th mission to carry Starlink satellites into orbit, but the Starlink spacecraft deployed on the network’s first dedicated launch were designed to demonstrate satellite and payload performance. SpaceX has not said if any of those satellites might be incorporated into the operational fleet.

The Falcon 9 rocket can loft up to 60 Starlink satellites — each weighing about a quarter-ton — on a single Falcon 9 launch. But launches with secondary payloads, such as BlackSky’s new Earth-imaging satellites, can carry fewer Starlinks to allow the rideshare passengers room to fit on the rocket.

The initial phase of the Starlink network will number 1,584 satellites, according to SpaceX’s regulatory filings with the Federal Communications Commission. But SpaceX plans launch thousands more satellites, depending on market demand, and the company has regulatory approval from the FCC to operate up to 12,000 Starlink relay nodes in low Earth orbit.

Elon Musk, SpaceX’s founder and CEO, says the Starlink network could earn revenue to fund the company’s ambition for interplanetary space travel, and eventually establish a human settlement on Mars.

SpaceX fans sleuthing through coding on the Starlink website last month found images of a prototype version of the antenna consumers will use to connect to the Internet network.

Musk responded to the tweet, writing the the Starlink ground terminal “has motors to self-orient for optimal view angle. No expert installer required.”

SpaceX has not released pricing information for the Starlink service.

SpaceX says it will soon begin “beta testing” using the Starlink network. The company is collecting email information and mailing addresses from prospective customers, and SpaceX says it will provide updates on Starlink news and service availability to those who sign up.

The beta testing is expected to begin for users living at higher latitudes — such as the northern United States and southern Canada — where the partially-complete Starlink satellite fleet can provide more consistent service. SpaceX will send a Starlink kit including a small antenna, router and other equipment to people selected for beta testing.

Astronomers have raised concerns about the brightness of SpaceX’s Starlink satellites, and other companies that plan to launch large numbers of broadband satellites into low Earth orbit.

The Starlink satellites are brighter than expected, and are visible in trains soon after each launch, before spreading out and dimming as they travel higher above Earth.

SpaceX introduced a darker coating on a Starlink satellite launched in January in a bid to reduce the amount of sunlight the spacecraft reflects down to Earth. That offered some improvement, but not enough for ultra-sensitive observatories like the U.S government-funded Vera Rubin Observatory in Chile, which will collect all-sky images to study distant galaxies, stars, and search for potentially dangerous asteroids close to Earth.

SpaceX launched a satellite June 3 with a new unfolding radio-transparent sunshade to block sunlight from reaching bright surfaces on the spacecraft, such as its antennas. SpaceX says all Starlink satellites beginning with the spacecraft on the launch Friday will carry the sunshades.

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Follow Stephen Clark on Twitter: @StephenClark1.