The satellite was getting old, pushing 19 — an age that verges on geriatric in spacecraft years. Still, it was healthy and could perform its duties, beaming the Internet to cruise ships and airplanes, among other tasks.

Problem was, its fuel was running out.

Normally in such a case, the satellite would have flown to a designated graveyard orbit, thousands of miles above the Earth, where spent satellites go to die peacefully and out of the way of others.

Instead, two companies teamed up to extend the life of the satellite, known as Intelsat 901, for another five years. In February, a spacecraft built by Northrop Grumman reached the satellite more than 22,000 miles above the Earth, latched on to it and is now essentially serving as a tow truck. Northrop’s spacecraft, known as a Mission Extension Vehicle (MEV), has taken over propulsion and steering for the satellite, making sure it maintains its orbit and is pointing in the right direction.

And late last week, Intelsat and Northrop Grumman announced that 901 has now successfully resumed operations, albeit with the MEV tethered to its back.

The mission marked the first time two commercial spacecraft have docked with each other in space and holds the promise of limiting the amount of orbital debris, a growing and nettlesome problem, as well as creating a new business opportunity for companies in space.

“It proves that in-orbit servicing is real,” Jean-Luc Froeliger, Intelsat’s vice president of space systems engineering and operations, said in an interview. “This was a project that took years in planning. We had identified this satellite three years ago and decided it’s healthy but it’s going to run out of fuel in early 2020. And so rather than having to discard the satellite and retire it, we teamed up with Northrop Grumman to do this in-orbit servicing mission.”

The companies are planning to perform the feat again, perhaps later this year with a different aging satellite. And there is now hope that robots in space will be able to look after each other and touch off a new chapter in commercial space operations. About 20 satellites a year reach the end of their lives and could be rescued, Northrop Grumman said.

“This is further evidence that the technology is moving out of the realm of specialized government activities into the broader commercialized domain,” said Brian Weeden, director of program planning at the Secure World Foundation, a think tank. “That’s a pretty important step for this nascent sector that one day holds promise for a whole range of things, from not only life extension but to on-orbit repair, fueling, inspection, assembly and manufacturing.”

Space, while vast, has become increasingly littered with all sorts of debris, including dead satellites, spent rocket stages, even a spatula dropped by an astronaut on a spacewalk.

In 2007, China fired a missile that blew up one of its dead weather satellites. Two years later, an active U.S. communications satellite crashed into a defunct Russian spacecraft. Those two incidents alone created thousands of pieces of debris, raising concerns that junk in space can create more junk and lead to more collisions.

In orbit, items move incredibly fast — as much as 17,500 mph — so even a small piece of debris, such as a screw, can cause enormous damage. Being able to pull dead satellites out of major traffic lanes in space, then, would be a welcome step, officials said.

The mission comes at a time when there are increased concerns about adversaries’ activities in space. The Trump administration has established the Space Force, as a part of the Air Force, to help deter conflict in space. Satellites are vital to the way the Pentagon wages war. They’re used to detect missiles, to guide precision munitions, and to provide intelligence and communications. But the satellites are just sitting there, vulnerable. And potential adversaries such as Russia and China have demonstrated the ability to interfere with them — or take them out completely.

This month, for example, Russia tested a missile the Pentagon said was designed to take out satellites in space. The Pentagon denounced the test, with Gen. John W. “Jay” Raymond, the Space Force’s chief of operations, saying in a statement that it was “yet another example that the threats to U.S. and allied space systems are real, serious and growing.”

This year, the Pentagon said two Russian spacecraft got uncomfortably close to a sensitive U.S. satellite. The Russian spacecraft “exhibited characteristics of a space weapon,” Raymond said, and “conducted maneuvers near a U.S. government satellite that would be interpreted as irresponsible and potentially threatening in any other domain.”

Northrop and Intelsat said their mission was for commercial purposes only. But it involved a great number of technological advances, years of planning and then a few nail-biting moments, as the MEV approached slowly over a period of weeks.

“We didn’t make it on the first try,” Intelsat’s Froeliger said. “It required several tries to actually dock.”

Because the satellite was built at a time when in-orbit satellite servicing was “a remote concept,” he said, it didn’t have a docking port. So engineers had to get creative.

They built a probe on the MEV that could extend like an arm, reach into one of the satellite’s engine nozzles and then extend three fingers that acted like “an anchor in a wall,” he said. After the five years is up, the companies will decide to either extend the mission or deliver the satellite to the graveyard orbit.

Correction: An earlier version of this article incorrectly referred to Gen. John W. “Ray” Raymond as an Air Force general. He is now a general in the Space Force.