WASHINGTON — Increasing demand but decreasing budgets are putting a strain on NASA’s Deep Space Network (DSN), threatening its ability to provide communications for the agency’s science missions and Artemis lunar expeditions.
While pressures on the DSN, a system of antennas located in Australia, California and Spain used primarily for communications with spacecraft beyond Earth orbit, have been growing for years, the Artemis 1 mission and the demands it placed on the network laid bare the challenges NASA will face in the future, officials warned.
“When Artemis comes online, everybody else moves out of the way, and it’s an impact to all the science missions,” said Suzanne Dodd, director of the interplanetary network directorate at NASA’s Jet Propulsion Laboratory, during an Aug. 29 meeting of the NASA Advisory Council’s science committee.
In the case of last fall’s Artemis 1 mission, the Orion spacecraft itself took 903 hours of DSN time, while eight cubesats launches as secondary payloads took an additional 871 hours. Science missions that use the DSN lost 1,585 hours in the same period, including the James Webb Space Telescope, which lost 185 hours alone. NASA also deferred maintenance on the DSN during Artemis 1 to free up an additional 509 hours.
Accommodating Artemis missions also involves scheduling challenges as date shift, something the DSN had to deal with on Artemis 1 because of its delays. “We either have to clear everybody off the network for that launch window or we struggle — and our experience with Artemis 1 was struggling with trying to move everybody around and shift it for the Artemis 1 launch date.”
The amount of time used by the DSN on the cubesats took members of the science committee by surprise, and was a source of frustration for Dodd. “I’m not sure who thought it was a good idea” to put those cubesats on Artemis 1, she said. “I don’t think that’s a good use when your DSN is oversubscribed.”
Much of the DSN time used for the cubesats was on what she called “search and rescue” operations when they ran into problems. She suggested NASA refrain from such efforts if future Artemis missions carry cubesats.
“We probably spent a lot of time looking for these cubesats and things that didn’t work that, in the future, I would recommend that we don’t do,” she said. “If we don’t hear your signal, your mission’s over.”
Demand grows and budgets decline
The DSN will continue to see spikes in demand from future Artemis missions as well as overall growth from an increasing number of other missions, many of which are commercial or government robotic lunar missions. “We’re nearly doubling the load on the DSN,” Dodd said. “The load is increasing and it’s very stressful to us.”
That is compounded, Dodd said, by decreased budgets to operate the DSN. Its annual budget has fallen from $250 million in 2010 to $200 million today, with the budget projected to continue to decrease through the end of the decade. “Looking out to the 2030s, that really scares us on the DSN.”
There have been several past reports that have warned of strains on the DSN. That included an audit of the DSN published July 12 by NASA’s Office of Inspector General. That report concluded that the network “is currently oversubscribed and will continue to be overburdened by the demands created by an increasing number of deep space missions,” and that efforts to enhance the DSN with new antennas is behind schedule and over budget.
“These are all great and, I would say, very accurate lessons learned,” Dodd said of that report and others. “There’s no money coming to overturn those challenges.”
She cited as an example an incident during the Artemis 1 mission when a system called a private cloud appliance failed at a DSN site in Goldstone, California, causing a 33-hour outage. The network developed a solution that she said was not “over the top” to prevent it from happening again. “We got no funding for that.”
NASA is taking steps to address the demand on the DSN from Artemis missions, said Philip Baldwin, acting director of the network services division of NASA’s Space Communications and Navigation program. He outlined at the meeting a four-point plan that includes upgrades of DSN antennas, installation of new set of 18-meter antennas called LEGS devoted to lunar exploration services, development of lunar communications and navigation relay services around the moon and increased international partnerships.
However, he acknowledged that those steps alone, like the six-antenna LEGS network, will not solve all of DSN’s problems. “We’re talking about six antennas where we have a deficit of more than that.”
Studies help NASA identify gaps in the DSN, Baldwin said, but officials need to carefully articulate what they need given constrained budgets. “We can’t overreach here. We can’t just say, let’s double the DSN budget,” he said, noting that NASA was not expecting additional funding for DSN because of a debt-ceiling agreement enacted in June that keeps non-defense discretionary spending, which includes NASA, at 2023 levels for fiscal year 2024.
“We have reached a really critical point with the DSN’s aging infrastructure,” said Sandra Cauffman, deputy director of NASA’s astrophysics division, who has been involved in studies of the network, noting that challenges will continue even with upgrades like LEGS. “This scares us very much.”
It also scared members of the science committee. “We’ve clearly gotten a five-alarm fire bell,” said one committee member, Marc Weiser of RPM Ventures.
The DSN “is in a deep deficit, and I think the only way we’re going to get out of it is to spend the necessary resources not only to recover capacity but to increase capacity,” said Vint Cerf of Google, another committee member.
Members of the committee spent part of the meeting proposing recommendations to NASA to address the DSN’s problems, and considered elevating the problem to the National Space Council. However, Ellen Williams, chair of the science committee, noted that any recommendations could not be formally transmitted to NASA until they were approved by the full NASA Advisory Council, which is not expected to meet before November.