SpaceX’s final launch of the year set for early Tuesday, weather permitting

A Falcon 9 rocket emerges from SpaceX’s hangar at Kenned Space Center for the quarter-mile trip up the ramp to launch pad 39A. Credit: SpaceX

SpaceX’s 31st and final Falcon 9 launch of the year is scheduled to take off early Tuesday from NASA’s Kennedy Space Center, weather permitting, with a Dragon cargo ship carrying more than 6,500 pounds of supplies to the International Space Station.

With the upcoming flight, the privately-held company will launch a brand new Falcon 9 booster for just the second time in 31 missions in 2021. The year has seen SpaceX fly a reusable first stage for an 11th time, launch three crew missions, and 989 Starlink internet spacecraft, more than half of the company’s active fleet of broadband satellites.

SpaceX’s final launch of the year, and fifth of this month, is set for liftoff at 5:07:08 a.m. EST (1007:08 GMT) Tuesday from pad 39A at Kennedy Space Center.

Ground teams rolled the 229-foot (70-meter) launcher to the pad Sunday, then raised the rocket vertical on its launch mount at pad 39A. SpaceX did not perform a test-firing of the rocket on the pad, the booster — designated B1069 — is brand new and was hot-fired at the company’s test site in McGregor, Texas, after leaving its factory in Hawthorne, California.

“It’s been a record breaking year for SpaceX,” said Sarah Walker, director of Dragon mission management at SpaceX. “This is our 31st and final launch of 2021, which is a step above the 26 launches we completed last year.”

But the weather forecast is dicey Tuesday morning, with just a 30% chance of acceptable conditions for the instantaneous launch window.

A frontal boundary that passed through Florida’s Space Coast over the weekend is forecast to back-track north overnight, bringing windy conditions and rain showers to the area.

“Gusty showers and storms will accompany the warm front overnight, along with extensive mid and upper level cloudiness across the area ahead of the main low (pressure system),” the launch weather office from the U.S. Space Force’s 45th Weather Squadron wrote Monday. “Less than favorable conditions are expected for the primary launch window early Tuesday morning, with the main concerns associated with this weather being the cumulus cloud rule, thick cloud layer rule, and surface electric field rule.”

SpaceX has a backup launch opportunity at 4:44 a.m. EST (0944 GMT) Wednesday, when forecasters expected improved conditions at Kennedy Space Center. There’s a 70% chance of good weather at the launch site Wednesday morning.

But the weather team expects a moderate risk of upper level winds exceeding the Falcon 9 rocket’s safety criteria, and a high risk that offshore winds and waves might be out of limits for landing of the first stage on SpaceX’s drone ship “Just Read the Instructions.”

The portion of the space station in its orbit will prevent launch attempts Thursday and Friday, meaning the next opportunity after Wednesday would be on Dec. 25, Christmas morning, according to Joel Montalbano, NASA’s space station program manager.

The booster’s landing on the drone ship, if successful, would mark the 100th recovery of a Falcon first stage since landings began in 2015.

“To make it even more special, if the clouds part for us and we are able to launch on (Tuesday), and we do recover that booster, it will also be on the anniversary of our very first booster landing,” Walker said. “It was Dec. 21, 2015.”

SpaceX and NASA technicians loaded time-sensitive experiment samples into freezers on-board the Dragon cargo ship Monday in preparation for the countdown early Tuesday.

Walker said Monday that teams were not working on any technical issues ahead of launch, which will also mark the 31st and final orbital mission to depart from Florida’s Space Coast this year.

That will also set a new record for space launch activity at the Florida spaceport, one more than the 30 orbital flights launched from Cape Canaveral Space Force Station and Kennedy Space Center last year. The record set last year was the most orbital launches from the Space Coast in a year since 1966.

A Cargo Dragon spacecraft stands on top of a Falcon 9 rocket at NASA’s Kennedy Space Center in Florida on Dec. 20. Credit: Michael Cain / Spaceflight Now / Coldlife Photography

Assuming an on-time launch Tuesday, the Dragon capsule is set to dock with the space station’s Harmony module around 4:30 a.m. EST (0930 GMT) Wednesday.

The Dragon cargo ship flying to the space station this week will deliver 6,590 pounds (2,989 kilograms) of supplies and experiments, including packaging, to the research lab’s seven-person crew.

The station crew is set to receive holiday gifts and a feast packed inside the Dragon spacecraft.

“Every year, we do our best to send up some presents to the crew,” Montalbano said. “I won’t get in front of Santa Claus and tell you what’s going to be sent up, but we are going have some gifts for the crew.”

The meal includes turkey, green beans, fruit cake, and smoked seafood.

The mission will be SpaceX’s 24th resupply flight to the station since 2012 under multibillion-dollar contracts with NASA.

Here’s a breakdown of the cargo load:

• 2,468 pounds (1,119 kilograms) of science investigations
• 2,002 pounds (908 kilograms) of unpressurized payloads
• 852 pounds (386 kilograms) of crew supplies
• 724 pounds (328 kilograms) of vehicle hardware
• 400 pounds (182 kilograms) of spacewalk equipment
• 72 pounds (33 kilograms) of computer resources

The Dragon cargo ship will deliver four experimental CubeSats to the station from teams at Kennedy Space Center, Aerospace Corp., Utah State University, and Georgia Tech. The CubeSats will be robotically deployed outside the complex next year.

The scientific experiments launching to the space station include an investigation from Merck Research Labs studying monoclonal antibodies. The research focus of that experiment is on analyzing the structure and behavior of a monoclonal antibody used in a drug aimed at treating cancers.

Another experiment will assess the loss of immune protection in astronauts flying in space. Proctor & Gamble and NASA have partnered in another experiment to test the performance of a new fully degradable detergent named Tide Infinity, a product specifically designed for use in space.

Astronauts on the space station currently wear an item of clothing several times, then discard the garment. But crews flying to the moon and Mars won’t have the same supply chain of cargo missions to support them.

NASA says Tide plans to use the new cleaning detergent to “advance sustainable, low-resource-use laundry solutions on Earth.”

Two research pallets from the U.S. military’s Space Test Program are riding inside the Dragon spacecraft’s unpressurized trunk. The two payloads, named STP-H7 and STP-H8, will be transferred from the Dragon spacecraft to mounting points outside the space station using the lab’s Canadian-built robotic arm.

The STP-H7 payload package will be mounted outside the European Space Agency’s Columbus lab module, according to NASA. STP-H8 will be placed on the exposed science facility outside the Japanese Kibo lab.

Two weather instruments from NASA’s Jet Propulsion Laboratory are hosted on the STP-H8 experiment package.

One of them, called the Compact Ocean Wind Vector Radiometer, or COWVR, will measure the direction and speed of winds at the ocean surface. The Temporal Experiment for Storms and Tropical Systems, or TEMPEST, instrument looks at atmospheric humidity, according to NASA.

Scientists will test the instruments’ performance in space during a three-year primary mission. Simultaneous measurements of ocean winds and atmospheric water vapor profiles could improve storm forecasting and weather models.

Team members pose with the Compact Ocean Wind Vector Radiometer instrument at NASA’s Jet Propulsion Laboratory. Credit: NASA/JPL-Caltech

The COWVR instrument has been in development for a decade. It originally was designed to fly on a standalone military satellite to replace an instrument named WindSat that collects ocean wind data for the Defense Department.

WindSat is on the military’s Coriolis satellite, which has been in orbit since 2003 and is well beyond its design life.

A microwave instrument like COWVR or WindSat measures ocean winds through detecting naturally occurring microwave emissions from Earth’s surface. The microwave data can reveal the speed and direction of winds, useful in applications such as hurricane forecasting and naval deployments.

NASA partnered with the Defense Department in a $24 million program to develop a simplified, new-generation version of the WindSat instrument that can fit within smaller mass and volume constraints. The COWVR instrument weighs 130 pounds (59 kilograms), about an eight the mass of WindSat, and reduces the number of moving parts needed to spin the rotating microwave sensor and collect data.

The new instrument was reassigned from being hosted on its own satellite to a cheaper ride to the space station.

“COWVR has the distinct possibility of being an absolute game changer for our users,” said Don Boucher, principal scientist in the chief architect’s office in the Space Force. “It’s simpler to build, simpler to test, the timeframe to build the instrument is less – so you can build more of them for the same amount of money as one conventional radiometer. That has tremendous implications for our supply chain.”

The TEMPEST radiometer flying alongside COWVR will be sensitive to a different range of microwave signals that yield information about moisture in the atmosphere. The instrument, just the size of a cereal box, is a spare left over from a CubeSat program.

“TEMPEST brings to the table an ability to sense both the amount of atmospheric moisture and its vertical distribution,” said Steve Swadley, the lead for calibration and validation of microwave sensors at the U.S. Naval Research Laboratory in Monterey, California. “This is important both for numerical models and for characterizing the moisture surrounding tropical cyclones.”

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