US Space Command says it needs more maneuverable Ars Technica satellites

Imagine you bought a vehicle that was supposed to last eight years on a single tank of gas. You’d probably avoid hard accelerations, keep an eye on the fuel gauge, and not leave the driveway unless it was a vitally important trip.

That was the analogy drawn Thursday by Lieutenant General John Shaw, deputy commander of the US Space Command, for how the Space Force operates its reconnaissance satellites.

The way we’ve done space operations since the dawn of the space age is wrong, Shaw said at an event hosted by the Mitchell Institute for Aerospace Studies.

The military’s fleet of communications, navigation, early warning and surveillance satellites never leaves their operational orbits. Each spacecraft has a finite amount of fuel for its thrusters to change altitude or pitch (the angle of its orbital flight path relative to the equator).

But it’s time for the military to transcend the orbital limitations imposed by celestial mechanics on a satellite with a single fuel tank, Shaw said.

“There is an emerging set of platforms that we believe need to move beyond this positional approach,” he said. “And they probably have to spend most of their lives changing their energy state and maneuvering, instead of staying in orbit. We have satellites that have projected lifetimes measured in years and fixed fuel tanks, so we can’t do that. And that’s limiting our ability to do many things that we want to do at US Space Command.”

The US Space Command’s area of ​​responsibility extends from the top of the atmosphere to the Moon and beyond. The Space Force, established as a new military branch in 2019, is responsible for equipping Space Command and other regional commands around the world with weapons, sensors and personnel to respond to hostile threats.

“I Don’t Want Zeppelins Anymore”

Shaw, as a second-ranking general at Space Command, said his team needs satellites that continuously maneuver in orbit.

He used the example of the US military’s neighborhood surveillance satellites that wander in geosynchronous orbit more than 22,000 miles (nearly 36,000 kilometers) above the equator. In that orbit, a spacecraft’s speed matches the speed of Earth’s rotation, making the geosynchronous belt a popular location for valuable communications, signals intelligence, and missile warning satellites.

The Space Force’s Geosynchronous Space Situational Awareness Program (GSSAP) satellites are designed to approach and inspect other objects in the geosynchronous belt, keeping a close eye on Chinese and Russian spacecraft in similar orbits. The military has launched six GSSAP satellites to date.

“Their only purpose is to move along the geosynchronous belt and look at other platforms,” ​​Shaw said. “We’ll look into our platforms if something might be malfunctioning. And if there’s anything that’s acting suspicious, we’ll go check that too. It’s like the Coast Guard. We’ll look into it and make sure we better understand what it is.”

Shaw said the military is “constrained” in what it can do with GSSAP satellites because ground controllers “have to think in terms of months and years” of fuel life with any decisions about what and where to maneuver the spacecraft to approach another orbiting object. Each unit of fuel on a satellite results in the spacecraft’s ability to change its speed by a certain amount, a measure known as delta-V in spaceflight parlance.

“If we saw a satellite that was behaving suspiciously, but was sufficiently far from a GSSAP platform, it would take us a while to get there, given the tight fuel budget, and it could be determined that we just can’t get there because it’s not within in life. This is basic astrodynamics with basic delta-V limitations.”

“We can’t have these constraints in the future,” Shaw said.

Without the restriction of limited maneuverability, military satellites could respond “at will” to an adversary’s threats. A satellite that can continuously maneuver in orbit is also a less attractive target, Shaw said. “I think there is intrinsic deterrent value in our ability to understand what is happening in the domain and respond.”

One option to achieve this capability is in-orbit refueling.

“If I could refuel my GSSAP satellites once a month, we’d be running them completely differently than we do now,” he said. “They were operating at maximum thrust levels.”

But ground controllers have to factor in fuel budgets and carefully plan each manoeuvre. Low-impulse burns result in more gradual changes in a satellite’s orbit, often eliminating any chance of catching an opponent by surprise.

“Today we operate the GSSAP as if you were doing aerial reconnaissance with a Zeppelin,” Shaw said. “I mean, we can do this. But you’re not kidding anyone by saying you’re coming. And you’re operating at the whim of the domain, and you really need to figure out how I’m going to do it? very carefully because I have very little fuel. I don’t want any more Zeppelins.”

While a GSSAP satellite, the Zeppelin airship in Shaw’s analogy, is purely a reconnaissance platform, militaries may eventually want spacecraft with offensive and defensive capabilities, something like a fighter jet in the air force’s fleet.

“As we get more capability in the future that we see F-15s coming into orbit, we can’t fly an F-15 like we fly a Zeppelin,” Shaw said. “That won’t cut it.”

Getting serious about on-orbit refueling

The Space Force is working on projects to answer the call from space commands. The Army awarded a $44.5 million contract last year to Orion Space Solutions for the Tetra-5 experiment, a mission slated to launch in 2025 to demonstrate hydrazine refueling in geosynchronous orbit.

The Tetra-5 mission, developed in collaboration with the Air Force Research Laboratory and the Defense Innovation Unit, will consist of three small satellites. The Tetra-5 spacecraft will connect in geostationary orbit with a fuel depot provided by Orbit Fab and hosted on an Impulse Space satellite. Orbit Fab, with early investments from industry giants Lockheed Martin and Northrop Grumman, also provides the refueling port for the Tetra-5 demonstration. The fuel port is a device called a Rapidly Attachable Fuel Transfer Interface (RAFTI).

The Space Force is accelerating its efforts to field satellite-assist capabilities by focusing on technology that commercial companies already have in development, Maj. Gen. Stephen Purdy said in April. At the time, Purdy was in charge of the Space Forces securing access to the Space Division, but now works at the Pentagon in the Space Forces procurement department.

Civilian satellites could also be attractive customers for satellite utility companies.

“It’s amazing how many companies do in-orbit servicing and maneuvering; it’s actually hard to keep track of,” said Purdy. Last year, dozens of companies participated in a satellite servicing day organized by the Space Force.

Part of the Army’s initial experiments in satellite assist will involve testing standardized refueling interfaces. One such interface is Orbit Fabs RAFTI. Future satellites could be launched with integrated refueling intakes, but most military spacecraft in today’s fleet weren’t designed with maintenance in mind.

Other companies working on satellite maintenance or refueling include Maxar, which is the prime contractor for NASA’s OSAM-1 technology demonstration mission that will attempt to refuel an aging Landsat Earth observation satellite. OSAM-1, scheduled to launch in 2025, will attempt to demonstrate that a utility satellite can insert a refueling probe into the Landsat 7 satellite’s fuel tank “and not blow it up,” Purdy said. “It’s actually fascinating and I’m very, very interested to see how it works.”

SpaceLogistics, a subsidiary of Northrop Grumman, has docked two of its life extension vehicles to Intelsat satellites in geostationary orbit, providing maneuvering capabilities for spacecraft that are running low on fuel. The company plans to launch a series of mission extension pods, or jet packs, to provide years of additional propulsion for customer satellites in orbit.

Japanese company Astroscale is also developing experiments for in-orbit maintenance, with eventual plans to apply the technology to clearing space junk from orbit. Last month a US company called Starfish Space launched its first technology demo experiment for satellite maintenance, but the mission ran into problems soon after getting into orbit.

Russia regularly resupplies the International Space Station with Progress resupply freighters. And DARPA, the Pentagon’s research and development agency, tested the satellite maintenance and refueling technology on the Orbital Express mission in 2007, but there was no operational program ready to use it.

Maj. Gen. David Miller, the Space Forces director of operations, echoed Shaw’s comments about refueling the satellites. He said military satellite operators don’t want to get into a situation “where a single maneuver takes us out of combat or takes us off mission.”

But satellite assistance may not be the only solution, particularly in an era where companies like SpaceX have been developing mass-produced satellites for mega constellations, such as the Starlink network.

Shaw said the Space Force could also try to launch cheaper satellites on a more regular basis. “This is commodification,” he said she. “I’m getting a GSSAP (satellite) today, but I’ll need another in two weeks because I’m flying out. It’ll empty that gas tank fast.”

Whatever the solution, Space Command wants it in place within five years for satellites with missions that require extensive maneuverability.

“For any platform that we think should operate as a platform for dynamic space operations, by 2028, we want to have sustained maneuvering capability,” Shaw said.