After nearly breaking, NASA's Deep Space Network "worked well" on Artemis II - Ars Technica

Overview

After nearly breaking, NASA’s Deep Space Network “worked well” on Artemis II

“Some missions are using more than what their paperwork would say.”

Details

NASA pushed its Deep Space Network beyond its limits during the Artemis I mission nearly four years ago. The global array of deep space communications antennas couldn’t keep up with the routine demands of 40 robotic science missions and the extraordinary surge required by NASA’s Orion space capsule as it flew around the Moon.

The experience in late 2022 reduced or delayed downlinks from several high-profile science missions, including the James Webb Space Telescope and Mars rovers, as the data-hungry Artemis I mission took priority on NASA’s communications network. And that was before the first Artemis mission with astronauts onboard. When Artemis II launched April 1, NASA called upon the Deep Space Network (DSN) again to connect Mission Control to the Orion capsule as it soared more than a quarter of a million miles from Earth.

With a crew of four flying inside the spacecraft, the agency’s appetite for data from Orion on Artemis II was even higher than it was on Artemis I. But at a little more than nine days, the Artemis II mission was shorter than the 25 days Artemis I spent in space, helping alleviate the communications overload. Artemis I also launched 10 small Cube Sats into deep space, many of which required tracking and telecom services from the DSN. Artemis II carried fewer Cube Sats.

“We learned a lot on Artemis I, and we actually put some new processes in place ahead of Artemis II, mostly focused around coordination and our scheduling processes with all the missions, not just the Orion vehicle itself,” said Greg Heckler, deputy program manager for capability development in NASA’s Space Communications and Navigation Program. “I think that worked well.”

Heckler said NASA’s science division, responsible for most of the missions using the DSN, provided the network’s managers with “positive feedback” after Artemis II. But the limitations of the network and the high demand continue to “create some asset contention” among NASA’s missions.

“During Artemis I, we had a subsystem called the Private Cloud Appliance. This PCA actually failed during Artemis I. Because of that failure, that high visibility, we actually received some additional resources from our Moon to Mars program, and we were able to install, effectively, a new subsystem ahead of Artemis II,” Heckler said.

The demand for signal is only going up. NASA and its commercial and international partners plan to launch numerous missions to the Moon in the next few years. NASA is working with commercial providers to construct ground antennas for a dedicated network for Moon missions, called Lunar Exploration Ground Sites (LEGS), to free up more capacity on the DSN to support other spacecraft. Commercial companies are also developing data relay satellites to fly in orbit around the Moon, supporting future landers and construction of a Moon Base. High-bandwidth optical communications may be another solution. NASA successfully tested a laser communications terminal on the Orion spacecraft on Artemis II.

“We’re going to have to work as a community to deal with that higher level of contention during the Artemis missions themselves, but we’re doing everything to establish non-DSN, or new infrastructure, to take on that load and burden,” Heckler said Wednesday in a meeting of the Small Bodies Assessment Group.

The burden currently includes around 40 operating missions that rely on the DSN’s antennas in California, Spain, and Australia to stay in communication with Earth. Most of NASA’s missions outlive their original design lives, so they put demand on the network for longer as the agency launches new spacecraft.

About 40 more missions are projected to need the DSN over the next 10 years, and many of the 40 missions currently using time on the network will likely still be operating over that time. One of NASA’s most data-intensive missions, the Nancy Grace Roman Space Telescope, is scheduled for launch in August. It will return more data through the DSN than all of NASA’s previous astrophysics missions combined.

The 10 Cube Sats that launched as secondary payloads on Artemis I placed an unforeseen burden on the DSN. Some of the small satellites were lost soon after deploying from the rocket, and their operators called upon the DSN to use its giant antennas to search for the Cube Sats as they headed into deep space, further exacerbating the communications crunch the network was already experiencing with the Orion spacecraft.

“Before onboarding new missions to the DSN, we now strictly require a feasibility study to see if there’s enough capacity to make that type of commitment,” Heckler said. “So we’re trying to balance, through data and analysis, the new demands coming onto the system versus those legacy missions we have to support until they fly out due to natural causes.”

DSN managers are also working with NASA’s older missions, some of which continue to pull on the network decades after their launch, to understand how much capacity they will use. As these older missions got extended, some of them did not update the network on their needs. “Some missions are using more than what their paperwork would say,” Heckler said.

“Once that is in place, as we move forward with new mission commitments, we will just be more focused, I think, and more process-oriented in being able to commit to new missions or not,” Heckler said.

One constraint on the DSN is an accident last year that knocked one of the network’s three 70-meter (230-foot) antennas offline at the Goldstone Deep Space Communications Complex near Barstow, California. This antenna, along with similar ones in Spain and Australia, is used to communicate with some of NASA’s most distant missions.

The 70-meter dish was tracking NASA’s Juno spacecraft at Jupiter last September when it “over-rotated” and damaged cables and water lines in the facility’s fire suppression system. An estimated 200,000 gallons of water flooded the base of the antenna. The water contained glycol, causing it to be classified as an environmental hazard, officials wrote in a report after investigating the accident. The resulting flooding rendered the antenna inoperable.

Investigators cited several technical and process causes. After troubleshooting a problem with the antenna’s emergency stops, technicians at Goldstone “overrode and bypassed multiple safeguards that normally would have prevented over-rotation,” officials wrote in the report.

“The investigation revealed inadequate training, insufficient written procedures, a reliance on undocumented behaviors and tacit knowledge, and deficiencies in the antenna’s control logic,” officials wrote. “In addition to the root causes listed above, the hydraulic limit system—the final fail safe against over-rotation—was discovered to have been severely damaged to the point of inoperability in an unknown and undocumented prior incident.”

Work logs indicated the hydraulic limit system was last tested in 2004.

NASA officials estimate it will cost between

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Key Takeaways

• After nearly breaking, NASA’s Deep Space Network “worked well” on Artemis II

• “Some missions are using more than what their paperwork would say

• NASA pushed its Deep Space Network beyond its limits during the Artemis I mission nearly four years ago

• The experience in late 2022 reduced or delayed downlinks from several high-profile science missions, including the James Webb Space Telescope and Mars rovers, as the data-hungry Artemis I mission took priority on NASA’s communications network

• With a crew of four flying inside the spacecraft, the agency’s appetite for data from Orion on Artemis II was even higher than it was on Artemis I