SpaceX poised for back-to-back launches Sunday at Cape Canaveral

SpaceX is readying two Falcon 9 rockets for a pair of flights nine hours apart Sunday from separate pads along Florida’s Space Coast. Weather permitting, the back-to-back departures Sunday would mark shortest span between two orbital-class launches from Cape Canaveral since 1966.

SpaceX’s two missions Sunday come on the heels of a dramatic abort just before the planned liftoff of a powerful Delta 4-Heavy rocket early Saturday.

The triple-core Delta 4-Heavy rocket, built by United Launch Alliance, was counting down to launch at 3:28 a.m. EDT (0728 GMT) Saturday with a classified satellite for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

But a computer controlling the final moments of the countdown commanded an abort during the rocket’s ignition sequence.

A ULA spokesperson said one of the Delta 4-Heavy’s three Aerojet Rocketdyne RS-68A engines — mounted under the rocket’s starboard booster — had already ignited when the abort was triggered three seconds before liftoff. The starboard engine ignites first in the Delta 4-Heavy’s staggered engine startup sequence.

ULA said Saturday the Delta 4-Heavy launch would be grounded for a minimum of seven days while engineers examine the cause of the launch abort and configure the rocket for another countdown.

That sets the stage for SpaceX’s next two Falcon 9 rocket missions Sunday to carry 60 more Starlink broadband spacecraft and Argentina’s SAOCOM 1B radar observation satellite into orbit.

“SpaceX is targeting Sunday, August 30th, for two launches — a Starlink mission in the morning and the SAOCOM 1B mission in the evening,” the company wrote on its website.

First, a Falcon 9 rocket is scheduled to take off from pad 39A at the Kennedy Space Center at 10:12 a.m. EDT (1412 GMT) with the next batch of 60 Starlink satellites for SpaceX’s planned network to beam worldwide broadband Internet signals from space.

Around nine hours later, a different Falcon 9 rocket could launch from pad 40 at Cape Canaveral Air Force Station at 7:18 p.m. EDT (2318 GMT) with Argentina’s SAOCOM 1B radar observatory.

The dual blastoffs will be the 100th and 101st orbital launch attempts in SpaceX’s history, including flights of the light-class Falcon 1 booster beginning in 2006.

With the 60 satellites launching Sunday morning, SpaceX will have deployed 713 flat-panel Starlink spacecraft on 12 Falcon 9 rocket flights since May 2019. SpaceX’s Starlink “megaconstellation” is already the largest fleet of satellites in the world, but hundreds more will be launched in the coming months.

Jonathan Hofeller, SpaceX’s vice president of Starlink and commercial sales, said earlier this month that the company is building six Starlink spacecraft per day, and plans to launch Starlink missions at intervals of every two to three weeks until completing the initial Starlink network of around 1,440 satellites.

SpaceX has regulatory approval from the Federal Communications Commission to eventually operate nearly 12,000 Starlink satellites to blanket the planet with high-speed, low-latency Internet signals.

After heading northeast from Cape Canaveral, the Falcon 9 rocket will inject the 60 Starlink satellites — each weighing about a quarter-ton — into an elliptical orbit ranging in altitude between 132 miles and 213 miles (213 and 343 kilometers). The satellites, built at a SpaceX facility in Redmond, Washington, will deploy from the rocket’s upper stage around 15 minutes after liftoff from Cape Canaveral.

The satellites will unfurl solar panels, switch on their krypton ion thrusters, and begin maneuvering to an operating orbit around 341 miles (550 kilometers) above Earth. SpaceX has started “beta testing” of the Starlink network for prospective customers in Washington before commencing commercial service.

The SAOCOM 1B satellite awaiting launch Sunday evening was developed by Argentina’s space agency, CONAE.

Like its twin satellite SAOCOM 1A, the SAOCOM 1B spacecraft will scan the Earth with an L-band steerable synthetic aperture radar, enabling all-weather imagery of the planet day and night. Radar imagers can see through clouds and are effective 24 hours a day, but optical cameras are hindered by clouds and darkness.

Among other objectives, the SAOCOM satellites are designed to measure soil moisture and collect data for users in Argentina’s agricultural and forestry sectors.

The SAOCOM 1B satellite weighs around 6,724 pounds (3,050 kilograms) and is identical to SAOCOM 1A, according to Raúl Kulichevsky, executive and technical director of CONAE.

Kulichevsky said the Falcon 9 will place SAOCOM 1B into a 385-mile-high (620-kilometer) orbit, where it will double the observing capacity of SAOCOM 1A. The SAOCOM satellites work in tandem with Italy’s COSMO-SkyMed satellites to survey the same regions with L-band and X-band radar imagers.

“One of the main targets of the SAOCOM satellites is to provide information for the agriculture sector because one of the things we develop is soil moisture maps, not only of the surface, but taking advantage of the L-band capabilities, we can measure the soil moisture 1 meter the surface of the land,” Kulichevsky said. “This is very important information.”

The entire SAOCOM project cost about $600 million, including two satellites, two launches, a new ground tracking station, and industrial improvements, Kulichevsky told Spaceflight Now in an interview.

Two small rideshare payloads will ride into orbit with SAOCOM 1B.

After releasing SAOCOM 1B around 14 minutes into the mission, the Falcon 9 will deploy two smaller satellites named GNOMES 1 and Tyvak 0172 about an hour after liftoff, according to SpaceX.

The GNOMES 1 microsatellite is the first of a planned fleet of around 20 small spacecraft being developed by a Colorado-based company PlanetiQ to collect radio occultation data by measuring the effects of the atmosphere on signals broadcast by GPS, Glonass, Galileo and Beidou navigation satellites. The information can yield data on atmospheric conditions that are useful in weather forecasts.

Tyvak 0172 is a small spacecraft built by Tyvak Nano-Satellite Systems. Details about its mission have not been disclosed by SpaceX or Tyvak.

SpaceX plans to land the first stage booster from the Starlink mission on a drone ship positioned in the Atlantic Ocean northeast of Cape Canaveral. The first stage from the SAOCOM 1B mission is due to return to Cape Canaveral Air Force Station for an onshore landing less than 10 minutes after liftoff.

One of SpaceX’s two vessels tasked with retrieving payload fairing shells — which jettison a few minutes after launch — is in position northeast of Cape Canaveral to recover the two-piece shroud from the Starlink mission. Another boat is south of Cape Canaveral near the recovery zone for the fairing shells from the SAOCOM 1B launch.

Both launches Sunday will employ previously-flown Falcon 9 rocket boosters. But the weather forecast is iffy Sunday.

In the official launch weather outlook for Sunday morning’s Falcon 9 launch, the U.S. Space Force predicts a 50 percent chance of favorable weather, with “considerable” mid-level and high-level clouds expected over Florida’s Space Coast. The prime weather concern for the Falcon 9/Starlink mission is the potential of violating the thick cloud rule.

There’s just a 40 percent chance of acceptable weather predicted for launch of the SAOCOM 1B satellite Sunday evening, due to the “threat of evening thunderstorms and associated cloudiness over the launch area,” according to the 45th Weather Squadron.

If they both take off as scheduled, the dual Falcon 9 launches planned Sunday would make history.

The last time Cape Canaveral hosted two orbital launches in a shorter period of time was Nov. 11, 1966, when an Atlas-Agena and a Titan 2 rocket launched just 99 minutes apart from different pads, according to a launch log maintained by Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics who tracks global satellite and launch activity.

The Atlas lofted the Agena target vehicle used for docking by the two-man Gemini 12 crew, which launched on the Titan 2 rocket the same day.

Speaking with reporters earlier this week, Brig. Gen. Doug Schiess — commander of the 45th Space Wing which runs the Eastern Range — said the range has shortened the time it needs to reconfigure between missions.

“The launches are continuing to increase,” Schiess said. “That’s due in part to our national security space missions, and a huge part is our commercial missions.

“We want to be a range that’s resilient and reliable enough that any time anybody wants to launch, whether that’s a national security payload, a civil payload with NASA, or a commercial payload, that we’re able to do that,” Schiess said Tuesday.

While noting the busy launch manifest this week required some “scheduling gymnastics,” Schiess lauded the range’s partnership with ULA and SpaceX to help make it happen.

The advent of the autonomous flight termination systems, which would be activated to destroy a rocket if it flew off course, helps the range streamline operations required to support missions from Cape Canaveral. SpaceX’s Falcon rocket family uses the automatic destruct systems, while ULA’s Delta 4-Heavy and Atlas 5 rockets use an older flight termination system that requires a manual command to be sent from a control officer on the ground.

ULA’s next-generation Vulcan Centaur rocket will have the autonomous flight termination capability, which allows the range to support launches with smaller teams. The automated safety system also allows the range to accommodate more than one launch on the same day.

Before the introduction of the automated flight safety system and satellite-based GPS tracking, a network of tracking radars were required to monitor each rocket’s flight path to ensure it stayed within predefined corridors. Coupled with concerns over aging range infrastructure, that often required a minimum of two days between launches from Cape Canaveral in recent decades.

“Autonomous flight safety systems allow us to be much faster at this, so as the new rockets come online from ULA and others that will have autonomous flight system (systems), that will allow us to be even better at this,” Schiess said.

“It really just comes down to a collaboration effort and the ability to schedule everything, change the network over,” Schiess said. “That’s also some of the things we’re doing for the range of the future, to build us an architecture that will change over much faster, plug and play with our telemetry, and things like that.”

The SAOCOM 1B mission is noteworthy in another sense because it will be the first rocket launch from Cape Canaveral since 1969 to fly on a southerly course to deploy its payload into a high-inclination orbit that flies near Earth’s poles.

The unusual trajectory will require the Falcon 9 rocket to first fly south-southeast from Cape Canaveral over the Atlantic Ocean, then bend its course back to the west in a right turn to skirt the coast of South Florida.

Known as a “dogleg” maneuver, the right turn will ensure the rocket’s impact point never crosses Florida in the event of an in-flight failure that causes the vehicle to crash back to Earth. The launcher will then head over the Florida Straits and Cuba before placing the SAOCOM 1B radar satellite into orbit.

Range safety officials began studying the southerly launch trajectory after wildfires at Vandenberg Air Force Base — where nearly all the U.S. launches into polar orbit originate — threatened launch and payload processing facilities in 2016. It turned out SpaceX’s ability to return first stage boosters to controlled landings — rather than having them plummet unguided back to Earth downrange — and the Falcon 9’s use of autonomous flight safety system made the polar launch trajectory from Cape Canaveral feasible.

“What we came up with after we analyzed is SpaceX should be able to do it because of two things,” said Wayne Monteith, associate administrator of the FAA’s office of commercial space transportation. “No. 1, booster flyback, and No. 2, even more important, is autonomous flight safety because going south, the way the architecture of the command destruct systems are set up terrestrially, you’d be looking right up the plume, and you get signal attenuation, and you may not be able to … send command destruct.

“So with autonomous flight safety and booster flyback, we were able to provide for them what appeared to be a notional safe corridor from a safety perspective,” said Monteith, a former commander of the 45th Space Wing.

Schiess said the 45th Space Wing safety team worked with the FAA to approve the launch trajectory for the SAOCOM 1B. The FAA is charged with ensuring commercial rocket launches do not endanger the public.

Although the Falcon 9 rocket will follow a source that brushes the South Florida coast, population centers in that region will not be at risk from the launch because its “instantaneous impact point” — where debris would fall if the rocket failed — remains offshore due to the vehicle’s bending trajectory.

“Miami is not in any of those dangers from any of the launch or the ascent,” Schiess said. “It goes out and then starts on its southerly orbit. It will overfly Cuba, but it will be an altitude that we’re safe.”

The State Department is charged with notifying other countries of a rocket flight over their territories. Those notifications have been made for the SAOCOM 1B mission, according to Schiess.

“In this case, they would potentially overfly Cuba, and potentially overfly Central America,” Monteith told Spaceflight Now last year. “The flight corridor we looked at was coming down the Pacific side of South America. So you’ve got to jog through the isthmus. But you’re at an altitude at that point where there’s exceptionally minuscule danger or hazard to anybody below.”

A satellite launching from Cape Canaveral targeting a polar orbit in 1960 suffered an in-flight failure and spread debris over Cuba, reportedly killing a cow and prompting protests at the U.S. Embassy in Havana.

SpaceX elected to use the polar launch trajectory from Cape Canaveral to allow the company to reduce staffing levels at Vandenberg during a period with few launches there, Gwynne Shotwell, company’s president and chief operating officer, told reporters last year.

SAOCOM 1B was previously scheduled for launch in March, but Argentine officials called off the mission due to concerns about the coronavirus pandemic. Engineers placed SAOCOM 1B in storage at Cape Canaveral until early July, when engineers returned to Florida from Argentina to finish readying the spacecraft for liftoff.

The launch of SAOCOM 1B was again delayed from late July because the range was not available for the launch, according to SAOCOM 1B team members. Sources said the delay was caused by range safety and overflight concerns with the classified payload mounted on top of ULA’s Delta 4-Heavy rocket at a neighboring launch pad.

The southerly trajectory required for the SAOCOM 1B mission will take the Falcon 9 rocket on a track closer to the Delta 4 pad than for a typical launch toward the east.

The overflight range safety concerns associated with the Delta 4’s NRO payload appeared to suddenly evaporate without explanation Saturday, when military officials agreed to permit the SAOCOM 1B launch to go ahead.

A ULA spokesperson said the Delta 4-Heavy and its national security payload were secured after the aborted launch attempt early Saturday morning. The protective mobile gantry at the Delta 4 launch pad was moved back into position around the rocket, and the spokesperson told Spaceflight Now no further securing measures are needed before the SAOCOM 1B mission.

A spokesperson for the 45th Space Wing referred questions about the safety concerns to SpaceX. A SpaceX spokesperson did not respond to questions from Spaceflight Now on the matter.