U.S. military makes adjustments in GPS launch to allow for SpaceX booster landing

The U.S. military’s third GPS 3-series satellite, designated SV03, is prepared for encapsulation inside the payload fairing of its SpaceX-built Falcon 9 rocket. Credit: SpaceX

SpaceX is preparing for liftoff Tuesday of its first mission for the U.S. Space Force, a launch from Cape Canaveral that will deploy a new GPS navigation satellite using a redesigned profile to allow the Falcon 9 rocket’s first stage booster to reserve enough propellant for landing on SpaceX’s drone ship in the Atlantic Ocean.

The launch profile adjustment to make landing of the Falcon 9 booster possible ended up saving “several million dollars” for the military from the original SpaceX launch contract value of $96.5 million, according to Walter Lauderdale, mission director for the GPS SV03 launch from the Space Force’s Space and Missile Systems Center.

The U.S. Space Force’s third GPS 3-series navigation satellite is set for liftoff from Cape Canaveral’s Complex 40 launch pad during a 15-minute launch window opening at 3:55 p.m. EDT (1955 GMT) Tuesday. There’s a 60 percent chance of favorable weather, according to a forecast issued by the Space Force’s 45th Weather Squadron.

Built by Lockheed Martin, the spacecraft will join two previous GPS 3 satellites launched by SpaceX in 2018 and by United Launch Alliance last year.

Tuesday’s mission is the first by SpaceX for the Space Force since the establishment of the new military branch in December.

“This is our first U.S. Space Force launch, and we’re really excited about it and hope this is the first of many, many of those launches in the future,” said Lee Rosen, SpaceX’s vice president of customer operations and integration.

During a nearly 90-minute launch sequence, SpaceX’s Falcon 9 rocket head northeast from Cape Canaveral and propel the 9,505-pound (4,311-kilogram) GPS 3 SV03 spacecraft into an elliptical transfer orbit ranging between about 250 miles (400 kilometers) and 12,550 miles (20,200 kilometers) in altitude. The Falcon 9’s on-board computer will aim to release the GPS 3 SV03 satellite into an orbit inclined 55 degrees to the equator.

On SpaceX’s first launch of a GPS navigation satellite in December 2018, military officials required the launch company to devote all of the Falcon 9 rocket’s capacity to placing the spacecraft into orbit. That meant SpaceX could not install landing legs on the Falcon 9’s first stage or attempt recovery of the booster.

SpaceX lands, refurbishes and re-flies Falcon 9 first stages to reduce costs, and it is the only launch company that currently reuses rocket hardware.

The launch of the GPS 3 SV03 mission Tuesday is the first flight with a high-priority national security satellite that will reserve propellant for landing of the rocket. SpaceX has recovered rockets on previous launches with military payloads, such as a Falcon Heavy mission last June, but those missions carried experimental technology demonstration and research satellites — not operational spacecraft like a GPS satellite.

On SpaceX’s first GPS launch in 2018, the military required the Falcon 9 rocket to place the spacecraft into an orbit with a higher perigee, or low point, of more than 740 miles, or about 1,200 kilometers. Teams also loaded extra fuel into the GPS spacecraft as an extra precaution.

It was the first high-priority national security payload to launch on a SpaceX rocket, and it was also the first satellite in a new design of GPS spacecraft.

“Simply put, there was insufficient performance given the mission trajectory and payload weight, combined with the uncertainties associated with this demanding mission,” Lauderdale said.

“Our evaluation of that mission’s performance, combined with additional work with SpaceX, reduced uncertainty in many areas,” Lauderdale said. “When we approached SpaceX to revise some spacecraft requirements for this mission … they responded with an opportunity to recover the booster in exchange for adding these requirements, as well as other considerations.”

SpaceX’s Falcon 9 rocket is prepared for rollout to Cape Canaveral’s Complex 40 launch pad. Credit: SpaceX

Officials are now more comfortable with the performance of the Falcon 9 rocket and the new GPS 3-series satellite design. That allowed engineers to load less propellant into the third GPS 3 satellite.

Mission planners also changed the perigee of the spacecraft’s initial orbit after launch from around 740 miles to 250 miles, according to Col. Edward Byrne, senior materiel leader at SMC’s Medium Earth Orbit space systems division.

“All that required from us was to reassess our burn profile, so we made some slight modifications to that burn profile, but there’s been no mission impact associated with the booster recovery option,” Byrne said in a pre-launch conference call with reporters.

One change to the Falcon 9 rocket requested by the Space Force for the GPS SV03 mission is a gray band of thermal insulation on the launcher’s upper stage. The thermal layer will help maintain kerosene fuel at proper temperatures during a nearly one-hour coast phase between the first and second burns of the upper stage’s Merlin engine.

SpaceX has tested the thermal layer before, but it did not fly on the first GPS 3 launch in 2018. The company has experimented with long-duration coasts of the Falcon upper stage to gather data before the first dedicated launch of a national security payload on SpaceX’s triple-core Falcon Heavy rocket late this year.

Military engineers charged with overseeing the design and production of SpaceX rockets for national security missions assessed numerous configuration changes since the Falcon 9’s first launch of a GPS satellite in 2018.

“Since the GPS 3 launch in December 2018, we’ve worked with SpaceX to stay current on the configuration of the Falcon 9, evaluating 665 changes,” Lauderdale said. “This enabled us to maintain the vehicle technical baseline that is the foundation of our independent mission assurance.”

The military has contracted with SpaceX to launch the fourth, fifth and sixth GPS 3 satellites. Assuming the launch of GPS SV03 goes according to plan, the SV04 mission could launch from Cape Canaveral on a Falcon 9 rocket as soon as Sept. 30, according to the Space and Missile Systems Center.

The GPS SV05 spacecraft is scheduled for launch on a Falcon 9 rocket in January.

Space Force officials have not yet approved SpaceX to launch critical national security satellites using previously-flown boosters. SpaceX has re-launched Falcon boosters 37 times to date with a 100 percent success record.

Lauderdale said the SMC mission assurance team is becoming more familiar with how SpaceX refurbishes rockets in between flights.

“I can’t commit to when we’ll be ready,” he said Friday, referring to when the military could launch a national security payload on a reused Falcon 9 booster.

SpaceX is building an all-new Falcon Heavy rocket for a national security launch late this year, and the company is expected to use a brand new booster for the next GPS launch no earlier than Sept. 30.

The military is currently considering proposals from four companies — SpaceX, ULA, Blue Origin and Northrop Grumman — in the next round of launch service procurements. Lauderdale said the military will allow launch service providers who win the the so-called “Phase 2” contracts to bid reused rockets for national security space launches in an effort to reduce costs.

“As a program, we are open and ready and looking forward to whatever industry wants to make available to us, but predominately we’ve been looking at the Phase 2 competition as that opportunity,” Lauderdale said.

A SpaceX Falcon 9 rocket stands vertical on pad 40 at Cape Canaveral Air Force Station before launch of the GPS 3 SV03 spacecraft. Credit: Lockheed Martin

The GPS 3 SV03 spacecraft awaiting launch Tuesday will use its on-board propulsion system to circularize its orbit after separation from the Falcon 9 rocket. It’s expected to enter service later this year.

Both of the previous GPS 3-series satellites are healthy, according to the U.S. Space Force’s Space and Missile Systems Center. They were “set healthy” and officially entered the operational GPS constellation Jan. 13 and April 1, an SMC spokesperson said.

The launch of the GPS 3 SV03 spacecraft is timed to inject the satellite into Plane E, Slot 4 of the GPS constellation. That position is currently occupied by a GPS satellite launched May 10, 2000, from Cape Canaveral on a Delta 2 rocket. Military officials did not say whether that satellite, which was originally designed for a 10-year mission, will be decommissioned or moved to another slot in the GPS network.

The GPS satellites are spread among six orbital planes, each with four primary spacecraft, plus spares. Byrne said Friday the GPS constellation currently consists of 31 satellites.

The GPS network provides positioning and timing services worldwide for military and civilian users, beaming signals relied upon by airliners, ATMs, drivers and smart bombs, among numerous other users.

“The Global Positioning System has become part of our critical national infrastructure, from transportation to financial markets to energy grids to the rideshare industry,” said Tonya Ladwig, acting vice president of Lockheed Martin’s navigation systems division. “It’s no longer a matter of did you use GPS today. It’s a matter of how many times did you actually use it.”

The GPS 3 satellites provide more accurate navigation signals and boasting longer design lifetimes of 15 years. The new GPS 3 satellites also broadcast e a new L1C civilian signal that is compatible with Europe’s Galileo network and Japan’s Quasi-Zenith Satellite System.

Other space-based navigation networks operated by Japan and China are also adopting similar compatible signals.

Like the previous line of Boeing-built GPS 2F satellites, all GPS 3-series spacecraft broadcast a dedicated L5 signal geared to support air navigation. The GPS 3 satellites also continue beaming an encrypted military-grade navigation signal known as M-code.

The M-code signal allows GPS satellites to broadcast higher-power, jam-resistant signals over specific regions, such as a military theater or battlefield. The capability provides U.S. and allied forces with more reliable navigation services, and could also allow the military to intentionally disrupt or jam civilian-grade GPS signals in a particular region, while the M-code signal remains unimpeded.

L3Harris Technologies builds the navigation payloads for the GPS 3 satellites.

Ladwig said the GPS 3 SV04 and SV05 spacecraft are complete and in storage awaiting launch, and the next three satellites are fully assembled and undergoing environmental testing. SV09 and SV10 are currently being assembled at Lockheed Martin’s GPS satellite factory near Denver.

Lockheed Martin is on contract with the Defense Department to build 10 GPS 3 satellites — two of which have launched — and up to 22 upgraded GPS 3F-series satellites.

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