On May 24, 2023, during the SETI Live: A Sign in Space - Simulating First Contact, the European Space Agency's ExoMars Trace Gas Orbiter (TGO) in orbit around Mars transmitted an encoded message to Earth to simulate receiving a signal from extraterrestrial intelligence.

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Friday 2nd of June

Could the Message be a mouse?
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Friday 2nd of June

Now that the message is confirmed, dozens of different theories about its interpretation have appeared. Each of them has its own dedicated thread in the #interpretation-chat channel in Discord, which now is much more active than ever. Here are some of the different topics seen around.
Does the Fourier transform give any useful information? This is similar to the pattern that you would get if you perforated the message on a piece of cardboard and shined light through it, due to diffraction.

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Does the message match the absorption spectrum of some chemical element?

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Is there any information encoded in how the message was split into pieces for transmission?

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Thursday 1st of June

The A Sign in Space Message.
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A dedicated group consisting of most of the active posters in ⁠decode-data-filter has converged on a very compelling message candidate.

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Wednesday 31 of May

The participants are now much more confident that the message is a binary file of 8212 bytes that was transmitted in 1800 pieces of 4 and 8 bytes. They also notice that Johannes Bauer, from ESA, had mentioned in the launch event that the message was transmitted with a command file of 1800 commands. The participants now set to document thoroughly all their work, so that people interpreting the message can know where the data came from and how it was processed.
Still, there are many things that are not clear about this strong message candidate. Is the "starmap" representation the correct one? Should it be plotted in color somehow? Is it even intended to be presented as an image? They also wonder about the pieces of 4 and 8 bytes. Does the size of the pieces mean anything?

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Wednesday 31 of May

One participant has found that the headers in TGO's space packets, which were mostly overlooked before, use an ESA protocol called PUS. These headers tell us something about the meaning of each packet: its purpose, and the kind of data it contains. With this new information, the participants quickly uncover the meaning of each of the packet "types" (APIDs) that appeared when the message reception began. APID 0017, which was considered as the main candidate for containing the message is seen to contain "memory dumps" from the spacecraft. The other APIDs contain information about the commands that the spacecraft executed to generate the memory dumps.

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Tuesday 30 of May

A large part of the conversation still revolves around the "star-map". Could it be pulsars? Active galactic nuclei? Molecular clouds? Maybe it is related to TGO's star tracker? These are cameras on the spacecraft that look at the stars to find how the spacecraft is oriented. In parallel, there are attempts to visualize the same data in a completely different way.
Also there is talk about whether some checksums could be intended to describe the absorption spectrum of a star or planet. These usually tell us much about their chemical composition. To sort out the files and code they are producing and the documentation they are using, some participants have assembled a repository in Github. It is very well organized, and it can help others to understand the previous steps in more detail.
Guithub link: https://github.com/BatchDrake/ASignInSpace

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No matter in which frames the data is...

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Monday 29 May

The participants continue to analyze the data in the three APIDs ("packet types") which are considered the most likely to contain the message. One of the three APIDs (the one numbered as 0x17) has received the most attention. When arranged in a particular way, some of the data in these packets forms a square image of size 256x256, with dots arranged in some clouds. What is this? The Pleiades? Another star cluster pointing to the location of the extraterrestrial intelligence? These are some of the ideas considered, but no one is quite sure. This image has been labeled as the best candidate found so far by some participants, but meanwhile the effort continues to explore other parts of the data and to find other possible ways to interpret the APID 0x17 packets.

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The Pleiades

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APID 0017 stripping the packets

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APID 0017

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Decoding state of the art pt.2

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Decoding state of the art pt.1

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Sunday 28 May

Noticing that part of the data was missing from earlier decoding attempts, the participants make some improvements to their approach and decode again the Green Bank Telescope SigMF recording. Now they carefully check the frame sequence numbers and CRCs to ensure that no data has been lost or corrupted. Plotting how the number of space packets in each APID ("packet type") increases over time, the participants notice that there are three APIDs that start transmitting packets only at the beginning of the message reception time on Earth (19:00 UTC plus a delay of about 16 minutes). They focus on the data in each of these APIDs, looking for patterns and producing visualizations and statistical analyses. Since the contents of the telemetry frames and space packets are solid at this stage, the organizers publish this information as the current state-of-the-art of the decoding process, allowing newcomers to join the decoding more easily.

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Saturday 27 May

The participants are studying the data in the space packets from different points of view. They try to find patterns, and plot the data in different ways. Some of the participants are still working on the earlier stages of the decoding process, with the SigMF recordings. They want to manage to decode them on their own to understand how this can be done. Other participants help them set up the software to do this.

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Friday 26 May

The organizers have hinted that the message is in the telemetry signal of TGO, intermixed with other data that is sent normally by the spacecraft. The participants now try to decode the telemetry signal. They have identified the CCSDS protocols used by TGO and obtained a binary file containing telemetry frames, and then produced another binary file containing the space packets which are contained in these frames. To make the space packet data more accessible, they have also made a CSV file which lists the sequence number, APID (roughly "type" of packet), length and contents of each space packet.

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Thursday 25 May

The SigMF recordings made at the Allen Telescope Array, Green Bank Telescope and Medicina Observatory have been made available for download. The participants have explored these recordings using different software. They have produced different visualizations and sonifications, and they have looked carefully at the spectrum of the radio frequency signal trying to find hidden signals.

Archive of the whole decoding and interpreting process in this page.

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Join us on the online (free) platform Discord, where the debate around decoding and interpreting the message is ongoing, with people from all over the world exchanging their thoughts while attempting to discover the signal's content.


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