ESA's satellite is dead. Its ghost: 2,123 signals. TabPFN beat the published SOTA; 83¢ of Tinker stopped an LLM speaking for it

Hacktoberfest Open-Source AI Challenge: Ghost in the Machine Submission 👻🌼

This is a submission for the Hacktoberfest Open-Source AI Challenge Week 4: Ghost in the Machine

2022-06-02 03:17:03 UTC I_PD3_THETA 0.0540137 2022-06-02 03:17:08 UTC I_PD3_THETA 0.0462915 2022-06-02 03:17:13 UTC I_PD3_THETA 0.0000000 2022-06-02 03:17:18 UTC I_PD3_THETA 0.0000000 2022-06-02 03:17:23 UTC I_PD3_THETA 0.0025708 Enter fullscreen mode Exit fullscreen mode Ten seconds of nothing. Recorded by a light sensor on a spacecraft that no longer exists.

ESA's OPS-SAT burned up in the atmosphere on 22 May 2024. Its engineers have moved on. Nobody is left to ask what happened at 03:17:13.

Ask a chatbot and it will tell you anyway. A sensor fault. A reboot. An eclipse. It will sound certain, and it will be making it up, because nothing in the archive says why.

So I built a séance with one house rule: nobody speaks for the dead.

The Last Satellite hands the archive to two open models:

Ask it why the light went out at 03:17:13, and you get the most honest sentence a medium can give:

"Root cause of this signal behaviour is not documented in the archive."

One confession before we start. My model looked at those ten seconds and called them 0.098: probably fine. It was wrong. That miss is in the demo, on purpose.

OPS-SAT was ESA's flying laboratory: a CubeSat that teams outside ESA could upload experiments to. Over four and a half years it sent home thousands of telemetry fragments. Then, in the words of its mission-end coverage, it was "impacted by the recent unexpectedly strong increase in solar activity that began in early 2024", and it came down early.

The labels say that something was wrong. Nothing in the archive says why.

That's the trap. Point a modern AI at this archive and ask "what happened to segment 204?" and it will give you a confident, plausible, completely made-up story. A sensor fault. A reboot. Cosmic rays. The data can't contradict it, because the people who could are gone.

The failure you have to fear isn't "the model is wrong." It's "the model invents a memory the archive doesn't hold, and you believe it."

The Last Satellite is a Mission Memory Engine: an archival investigation console with two open models, one evidence layer and one rule.

Why it fits Ghost in the Machine: this week runs from Halloween night into Día de los Muertos, when the line between past and present is supposed to be thinnest. OPS-SAT is a ghost in the most literal sense: a machine that no longer exists, still talking through 303,493 archived readings.

Día de los Muertos isn't about being afraid of the dead. It's about remembering them accurately: the ofrenda holds their real photos, their real favourite foods, their real stories. So the console is built like one. Marigold and candlelight, not horror. The satellite's own words are the offerings, every one sourced. And there's one rule a séance usually breaks: nobody gets to put words in the ghost's mouth. Not me, not the language model. Measured, cited, or unknown.

The video above is the whole tour. The console talks to the live FastAPI backend when it's running. Without it, it falls back to a labelled archived snapshot of real API responses, so it works anywhere.

The signal that should not be there. Pick one of six candles: six real segments from the official test split, labels hidden. Step through the signal, the 18 measured features, TabPFN's probability, the documents, the most similar past segments, and the investigation card. Then reveal the truth.

And the one it missed. The demo set deliberately includes the false alarm and a missed anomaly. Notice the banner on the summary: the fine-tuned interpreter's draft was rejected by the validator, so the card fell back to plain, deterministic text. More on that below.

Ask the archive. It tells you what it doesn't know.

The queue. 529 segments ranked by TabPFN, each with a card and three buttons: Confirm, Reject, Investigate.

Its mission ended. Its memories did not.

OPS-SAT was ESA's flying laboratory, a CubeSat that re-entered the atmosphere on 22 May 2024. This project is an archival analysis system built on its real, public telemetry and documents. It has two halves:

An evidence layer joins the two into investigation cards. Every statement on a card is either measured or cited, and an analyst can confirm, reject or investigate it.

Nothing here is live. All numbers below are produced by scripts…