Falcon 9 rocket returns to launch pad with Starlink satellites after delays

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

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

The 229-foot-tall (70-meter) launcher is expected to take off at 1:12:05 a.m. EDT (5:12:05 a.m. GMT) Friday from Kennedy Space Center station 39A along with 57 other Starlink satellites.

It will be the first SpaceX launch to carry a full set of Starlink satellites fitted with new sunshades, or visors, in a bid to make the spacecraft less visible to ground-based telescopes, addressing concerns expressed by astronomers than thousands of Starlink satellites could interfere with scientific observations.

“All of the Starlink satellites on this flight are fitted with a deployable visor to prevent sunlight from reaching the brightest points of the spacecraft – a step SpaceX has taken as part of our work with major astronomical groups. to attenuate the reflectivity of satellites, ”SpaceX says on its website. .

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

The mission that was scheduled to launch on Friday was originally scheduled to take off in late June, but SpaceX has delayed the flight several times. The company has not disclosed any details of the nature of the issues – other than weather – that delayed the Starlink / BlackSky mission.

The Starlink / BlackSky launch was supposed to take off on June 26, but SpaceX has delayed the mission to perform additional pre-launch checks, the company said on Twitter. An attempted launch on July 8 was cleaned up a few minutes before takeoff due to bad weather.

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

The concerns that delayed the launch of Starlink / BlackSky did not affect other SpaceX missions.

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

The Starlink / BlackSky launch was tentatively slated to launch last week from Kennedy Space Center, but there were safety concerns with the range of the Falcon 9 rocket taking off from a station near where the rover was. NASA Perseverance – with a nuclear power generator on board – was ready for takeoff.

SpaceX says the Falcon 9 rocket ready for launch Friday will be powered by a kerosene-powered first-stage thruster that has previously flown on four missions, starting with the launch of the company’s Crew Dragon spacecraft on its maiden flight. unmanned test to the International Space Station on March 2, 2019.

Since then, the reusable first-stage booster – designated B1051 – has been launched and successfully landed on mission on June 12, 2019, January 29, and April 22 of this year. This will be the fifth flight of this particular first stage thruster.

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 thruster lands on SpaceX’s drone on January 29 in the Atlantic Ocean following a previous Starlink launch. The same booster will be launched again during Friday’s mission. Credit: SpaceX

SpaceX’s launch team will prepare the rocket for loading supercooled and densified thrusters on Thursday evening, before the automated countdown sequencer begins at 12:37 a.m. EDT (4:37 GMT).

At this time, kerosene and liquid oxygen will begin to pump aboard the first stage of the Falcon 9 rocket, and kerosene will begin to flow into the second stage of the rocket. At 12:56 p.m. EDT (0456 GMT), SpaceX will begin filling the second stage with its supply of liquid oxygen.

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

Nine 1D Merlin engines will come to life at the base of the Falcon 9 rocket and hold down clamps will open to allow the launcher to fly off pad 39A at 1:12 a.m. EDT (5:12 GMT).

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

The booster will target a propellant landing on the floating platform nearly eight and a half minutes after the mission begins.

Meanwhile, the Falcon 9’s second stage will ignite its 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 motor will stop at T + plus 8 minutes, 51 seconds, to hit a hill on the other side of the world before re-igniting for a few seconds at T + plus 47 minutes, 18 seconds.

This will inject the Starlink and BlackSky satellites into a near-circular orbit with elevations between 388 kilometers and 249 miles (401 kilometers) above Earth, with a tilt of 53 degrees from the equator.

Both BlackSky satellites will deploy from the top of the Starlink 61 satellite stack and 66 minutes after takeoff.

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

The deployment of the BlackSky payloads will pave the way for the separation of the 57 Starlink spacecraft at T + plus 1 hour 33 minutes or 2:45 a.m. EDT (6:45 GMT).

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

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

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

Each of the flat-screen satellites weighs about a quarter of a ton and is built by SpaceX in Redmond, Washington. Once in orbit, they will deploy solar panels to start generating 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 to almost everyone in the world, and 12 launches could cover higher latitude regions, such as Canada and the northern United States.

Launch Friday will be the 10th mission to transport Starlink satellites into orbit, but the Starlink spacecraft deployed on the network’s first dedicated launch was designed to demonstrate satellite and payload performance. SpaceX has not said if any of these satellites could be integrated into the operational fleet.

The Falcon 9 rocket can carry up to 60 Starlink satellites – each weighing about a quarter of a ton – on a single Falcon 9 launch. But launches with secondary payloads, such as the new Earth imaging satellites of BlackSky, can carry fewer Starlinks to allow carpool passengers to adapt to the rocket.

The initial phase of the Starlink network will have 1,584 satellites, according to SpaceX regulatory filings with the Federal Communications Commission. But SpaceX plans to launch thousands of additional 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.

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

Last month, SpaceX fans digging through the coding on Starlink’s website found images of a prototype version of the antenna that consumers will use to connect to the Internet.

Musk responded to the tweet, writing that the Starlink ground terminal “has motors to self-steer for the optimum viewing 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 potential customers, and SpaceX says it will provide updates on Starlink news and service availability to those who sign up.

Beta testing is expected to begin for users living in higher latitudes – like 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 that includes a small antenna, router, and other gear to those selected for beta testing.

Astronomers have expressed concern about the brightness of Starlink satellites from SpaceX and other companies that plan to launch large numbers of broadband satellites into low earth orbit.

Starlink satellites are brighter than expected and are visible on trains shortly after each launch, before expanding and darkening as they travel higher above Earth.

SpaceX introduced a darker coating on a Starlink satellite launched in January in an effort to reduce the amount of sunlight reflected from the spacecraft back to Earth. This has offered an improvement, but not enough for ultra-sensitive observatories like the US government-funded Vera Rubin Observatory in Chile, which will collect images from the sky to study distant galaxies, stars and search for potentially asteroids. dangerous close to Earth.

SpaceX launched a satellite on June 3 with a new, fold-out radiolucent sunshade to prevent sunlight from reaching the spacecraft’s bright surfaces, such as its antennas. SpaceX says all Starlink satellites from the spacecraft at launch Friday will carry the umbrellas.

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Follow Stephen Clark on Twitter: @ StephenClark1.

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