Il video clip è leggermente fuorviante e presenta un po 'di semplificazione di ciò che sarebbe realmente accaduto. In realtà, ciò che l'MRO avrebbe ricevuto era un segnale portante, che sarebbe poi stato ritrasferito sulla Terra e analizzato da scienziati e ingegneri per gli indizi sul successo della missione.
Come spiegato da Michel Denis, Mars Express Spacecraft Operations Manager, e riportato sul sito web dell'ESA :
"Only Odyssey can receive, decode and then relay to Earth the actual telemetry data coded into the those signals. Conversely, MRO and MEX will save on board 'open-loop' recordings," says Denis.
Michael Khan, un analista di missione presso l'ESOC, ha confermato questo per Mars Express, come riportati sul blog Mars Express :
"All that Mars Express will receive is the UHF [radio] carrier signal. From apparent changes in the received frequency, one can deduce at which speed relative to the MEX the landing craft is moving. Or -- hopefully this will not be the case -- if suddenly the signal stops, then we have an indication of when things went awry," he points out.
"Mars Express can and does relay data for surface assets. But that is long after landing and requires MEX to pass very low over the landing site; not the situation we will have on Monday, 6 August."
E sono entrati un po 'più in dettaglio nel processo di registrazione a ciclo aperto in un post di follow-up, " Cos'è la registrazione ad anello aperto? ":
In open loop recording, we don't try to decode the bits and bytes being sent by the descending lander but instead try and listen to as much of the radio spectrum as we can, hopefully detecting the tone of the lander's transmissions within this spectrum. Think of it like listening to a crowd of people – you can either focus on the words one person is saying, or listen to the whole crowd to get a full picture of what's going on; that's what we'll do with open loop recording.
On Mars Express we'll use our UHF Melacom radio to listen in on the UHF part of the spectrum – usually used on Earth for radio and television transmissions; it's also used at Mars as the frequency that different orbiters and landers use to talk to each other.
[...]
By using this technique, we will see the trace of Curiosity's signal in the UHF and X-Band ranges and watch as it drifts and changes in response to Doppler, in this case not just because Mars Express is moving overhead but also because Curiosity will be changing velocity as it slows itself to a soft landing on Mars. This will give us a great insight into the progress and success of the landing.
Questo processo di analisi del segnale è ciò che avrebbe richiesto ore. Naturalmente, non era necessario in quanto Curiosity era in grado di trasmettere dati all'orbita di Mars Odyssey, e probabilmente non sarebbe più necessario per il resto della missione.