How a Long-Dead NASA Satellite Spoke Again After 60 Years.

"The Ghost Signal: How a Long-Dead NASA Satellite Spoke Again After 60 Years"

In June last year, astronomers working with the Australian Square Kilometre Array Pathfinder (ASKAP) were on the hunt for distant fast radio bursts (FRBs)—mysterious and energetic pulses from across the universe. Instead, they stumbled upon something far closer to home: a powerful, fleeting radio flash that temporarily outshone everything else in the sky. Upon tracking it down, they were startled to find its origin wasn’t a distant galaxy—it was NASA’s Relay 2 satellite, launched in 1964 and deactivated by 1967. A relic of the early Space Age, Relay 2 had been silently orbiting Earth for nearly 60 years before unexpectedly “speaking” again

What Happened?

On June 13, 2024, the ASKAP team detected a radio burst lasting less than 30 nanoseconds, with a peak intensity surpassing 300 kJy—a signal so strong it temporarily eclipsed every other radio source in the sky. 

Analysis linked the burst to low-Earth orbit (~12,400 miles above the Earth), and cross-referencing with satellite databases revealed the culprit: Relay 2—a communication satellite that NASA used in the mid-1960s and considered dead since 1967

Possible Explanations

Since Relay 2 has been inactive for decades, the pulse couldn't have been a deliberate broadcast. Researchers suggest two likely causes:

1. Electrostatic discharge (ESD)

• Spacecraft can accumulate charge through solar and cosmic radiation. When enough builds up, a spontaneous discharge can occur, releasing a burst of energy—and in this case, a powerful radio pulse

2. Micrometeorite impact

• A tiny particle striking the satellite could vaporize part of its outer shell into plasma, producing an electromagnetic pulse detectable from Earth

Karen Aplin from the University of Bristol explains that both scenarios offer similar outputs, making it tricky to distinguish between them. Regardless, each holds scientific value, since understanding these events can inform satellite design and space debris monitoring

Why It Matters

This unlikely detection highlights a clever new tool in the toolbox for space monitoring:

• Space debris tracking:
  In an era where countless satellites and debris orbit Earth, unexpected radio flares could serve as natural beacons—revealing orbits, material wear, or impacts in real time .

• Protecting active satellites:
  Electrostatic discharges can pose operational risks. Monitoring such events provides insight into how to shield or better design spacecraft to endure charge buildup .

• Astrophysics calibration:
  A powerful Earth-orbiting signal can skew radio astronomy observations. Recognizing such "local interference" helps astronomers clean their data and remain alert to terrestrial influences

Echoes of Zombie Satellites

Relay 2 isn’t alone in occasional reappearances. Other long-dead satellites have seemingly “come back to life”:

• Galaxy 15 (2005) — went rogue in 2010 but spontaneously rebooted later that year.

• AMSAT‑OSCAR 7 (1974) — ceased function in 1981, then miraculously resumed transmissions in 2002 near the end of a preprogrammed timer’s cycle

These events reveal how dormant satellites can unpredictably return to transmitting—a mix of design quirks, time-delayed circuits, or external triggers like particle impacts.

What Comes Next?

The detailed study, now published in The Astrophysical Journal (via arXiv), recommends researchers:

• Monitor space more vigilantly for unplanned radio bursts from orbit.

• Correlate these events with space weather (solar activity) and micrometeorite flux.

• Use radio observatories like ASKAP proactively for debris and anomaly tracking.

As Karen Aplin notes, “this radio detection may ultimately offer a new technique to evaluate electrostatic discharges in space”. These insights could reshape how we safeguard—or at least catalog—Earth’s increasingly populated orbital environments.

Final Thoughts

Relay 2’s sudden radio burst is more than a quirky footnote in space history—it’s a ticking reminder that even decades-old satellites can flash back into the spotlight in dramatic ways. It underscores the unpredictable nature of orbital space, where ancient junk, micro‑impacts, and electric charge collude to create phenomena that surprise even seasoned space-watchers.

This event offers a promising pivot: using radio astronomy not just for cosmic exploration, but as a sentinel keeping tabs on humanity’s growing footprint in orbit. As our skies grow busier, maybe the best debris-tracking tools will be the very signals we once thought were "from beyond."