NASA could lose contact with the Hubble Space Telescope and the International Space Station by the end of this decade. The satellites that keep those missions connected to the ground are dying, and the spacecraft themselves cannot be retrofitted with new radios. If the agency doesn’t secure a replacement communications system before its aging Tracking and Data Relay Satellite System fails, Hubble goes quiet and ISS crew safety is compromised. That’s the backdrop for Project NEXUS, a program NASA announced in April to replace TDRSS with commercial Ka-band relay services—and a bet that private industry can deliver the reliability the agency needs before hardware clocks run out.
The Problem: Hardware That Can’t Be Swapped
TDRSS has been NASA’s primary relay system for communicating with spacecraft in low Earth orbit since the 1980s. The constellation routes data through geosynchronous relay satellites rather than relying on brief windows when a spacecraft passes over a ground station, enabling nearly continuous contact with ground controllers. But the satellites are wearing out, and NASA has been gradually retiring them.
The agency’s concern is blunt: older missions designed around TDRSS cannot transition to alternative communications systems. Their Ka-band transponders are fixed. You can’t send a repair crew to Hubble to install a new radio. NASA has stated that these missions risk loss of telemetry, tracking, and command services, which directly impacts mission safety and scientific return. For a telescope that still produces significant science, that means lost data. For a space station that still carries crew, it means something worse.
This isn’t a theoretical worry. The Artemis 2 mission relied on TDRSS for communications during its final descent phase, switching from the Deep Space Network to the relay satellite system as the Orion capsule approached Earth. That kind of dependency shows how deeply embedded TDRSS remains in NASA’s operational architecture, even as the system approaches what the agency has identified as concerns about service continuity at the end of the decade.
What NEXUS Actually Is
NEXUS stands for Network Extension for User Continuity and Sustainability. It falls under the broader Commercial Services Project, which represents NASA’s strategic shift from owning and operating its own communications infrastructure to purchasing services from private companies.
The core requirement is backward compatibility. Whatever commercial system replaces TDRSS needs to work with the Ka-band transponders already on orbiting spacecraft. The signal format has to match what’s already flying, which is both a technical constraint and a market filter—not every satellite communications company can offer relay services in the specific Ka-band configuration that TDRSS uses.
Kevin Coggins, NASA’s deputy associate administrator for the Space Communications and Navigation program, discussed the institutional challenges of this kind of transition at a symposium hosted by the Universities Space Research Association and Space Policy Institute. Moving away from long-standing systems that are reaching end of life is hard enough. Doing it on a deadline set by failing hardware makes it harder.
Coggins also indicated that NASA will coordinate with the National Telecommunications and Information Administration to ensure that companies participating in NEXUS can access the Ka-band spectrum currently reserved for TDRSS. Spectrum allocation is one of those bureaucratic details that can quietly kill a program if not resolved early.
Three Phases, Then a Long Contract
The program is structured as a competitive funnel. Phase 1 gives companies time to mature their concepts for an end-to-end TDRSS replacement. NASA plans to select multiple companies for this initial stage, casting a wide net across the satellite communications sector.
Phase 2 narrows the field. Selected companies from Phase 1 will develop their systems and conduct ground tests. Phase 3 is an on-orbit demonstration, the point where paper designs have to prove they work in space.
After those demonstration phases, NASA plans to hold separate competitions for companies to actually provide relay services. Those contracts would run for an extended period. For companies that make it through the gauntlet, the payoff is a long-duration government customer with guaranteed demand.
NASA has not disclosed a budget for NEXUS. That omission is worth paying attention to. The absence of a public number could mean the agency is still working through appropriations, or it could mean NASA wants to see what industry proposes before anchoring expectations to a specific figure.
The Timeline Is Tight
NASA expects to release the final solicitation in mid-May, with proposals due in early June. Companies serious about competing have likely already started their concept work based on the draft.
Phase 1 work is slated to begin later this year. If the timeline holds, that puts the on-orbit demonstration phase sometime in 2027 or early 2028, depending on how tightly the phases overlap. The end-of-decade window when TDRSS satellites start failing doesn’t leave much margin.
The compressed schedule reflects the urgency of the continuity risk. If commercial services aren’t ready before critical TDRSS satellites die, NASA faces a communications gap with no workaround for missions that were built around the existing system.
A Template for Deeper Space
NEXUS is framed as a near-term solution for low Earth orbit, but NASA is signaling that it wants the program to serve a broader purpose. The draft solicitation explicitly connects NEXUS to future communications needs for lunar and Mars exploration.
The agency has stated that although NEXUS is focused on near-term relay continuity, it strengthens the industrial base, matures commercially provided relay services and demonstrates acquisition and operational approaches that are directly relevant to the communications architecture needed for future lunar and Mars missions.
This framing matters for understanding what NASA is trying to build. The agency isn’t just buying a replacement for old satellites. It’s trying to create a commercial market for deep space relay services, using TDRSS replacement as the first contract that proves the model works. If commercial providers can handle Ka-band relay in LEO reliably and affordably, the argument for extending that model to cislunar space and eventually Mars communications becomes much easier to make.
The approach mirrors what NASA did with commercial cargo and crew services to the ISS. Start with a defined need, use phased competitions to develop commercial capability, and then transition from development contracts to service purchases. The Commercial Orbital Transportation Services program that eventually produced SpaceX’s Dragon and Orbital Sciences’ Cygnus followed a similar logic.
Who Might Compete
NASA hasn’t named specific companies it expects to bid, but Coggins said the agency hopes to attract broad interest from the satellite communications sector. The broader push toward commercial satellite communications services at NASA has been building for several years, with the agency gradually shifting new missions away from government-owned relay infrastructure. NEXUS addresses the harder problem: what to do about missions already in orbit that can’t be upgraded.
Companies that already have or are developing geostationary or high-orbit relay capabilities may have an advantage. The extended service period also favors companies with the financial staying power to maintain constellation operations over many years.
The Institutional Bet—and the Risk That Matters Most
NEXUS represents a specific bet about how NASA should manage its infrastructure: that the agency is better off buying communications as a service than building and operating its own satellite fleet. This is the same logic that drove commercial cargo and commercial crew. The modernization of NASA’s space network has been an ongoing effort, but NEXUS marks a clear decision point where the agency is committing to commercial provision rather than a next-generation government system.
The reward, if it works, is a communications architecture that doesn’t require NASA to build, launch, and operate its own relay constellation. That frees up budget and institutional attention for the science and exploration missions that are NASA’s reason for existing.
But the risk is the one that should keep program managers awake at night. Commercial communications providers are accustomed to serving customers who can tolerate occasional outages. A streaming service drops for thirty seconds and someone misses a line of dialogue. A relay link to the ISS drops during an emergency and a crew doesn’t receive a critical command. Those are not the same problem. NASA’s crewed missions require near-continuous coverage with reliability standards that the commercial sector has never been asked to meet for an outside customer.
If no commercial provider delivers a system that meets those requirements on time, there is no fallback. The TDRSS satellites don’t care about procurement timelines. They will fail according to their own hardware clocks. NASA would be left with degrading communications for a crewed space station and no government-owned replacement in the pipeline, because the agency is betting this transition on industry.
Proposals are due in the coming weeks. The clock on TDRSS is already running down. What NASA is really asking industry is whether it can match the reliability that human spaceflight demands—not just the signal format, but the standard of service where failure isn’t a contract penalty but a threat to crew safety. The answer will determine whether this transition becomes another successful chapter in NASA’s commercialization playbook, or a cautionary tale about trusting the market with missions where the margin for error is zero.
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