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The ExoMars Entry, Descent and Landing Demonstrator Module (EDM) Schiaparelli was configured to broadcast a UHF beacon throughout the entry, descent and landing phases using multiple transmitters and antennae. The Giant Meter Wave Radiotelescope (GMWR) - an array of roughly 30 dishes of 45 meters diameter each - was able to receive the signal during at least the first part of the descent.

Were the previous Mars landers configured to transmit beacon signals, or even data during entry, descent, and/or landing?

It doesn't have to be intended to be heard on Earth - configuration to signal an orbiting spacecraft counts too.

edit: I had originally read (somewhere) that Schiaparelli was only transmitting a beacon signal. But after reading this BBC article I found this ESA update Schiaparelli Descent Data: Decoding Underway that explains that the transmissions were spacecraft telemetry, and it was received both by the GMWR on Earth, and by the orbiter ExoMars TGO satellite - even while it was busy putting itself into Mars orbit.

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Only Mars Polar Lander and Beagle 2 didn't. (Both when we would have wanted it the most, of course.) Mars Pathfinder's was limited to carrier, Doppler, and one subcarrier semaphore every 10 seconds on a direct-to-Earth link, since there were no relay orbiters there yet.

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    $\begingroup$ I thought Beagle2 didn't either, and one of the outcomes of the ESA analysis was that all future landers should. $\endgroup$ – JCRM Nov 2 '17 at 8:34
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    $\begingroup$ Good point! I was only thinking of US missions. $\endgroup$ – Mark Adler Nov 2 '17 at 15:29
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Yes, in fact, there have been several. It's not easy to figure out exactly which ones had such a system, but I'm sure Curiosity did. Usually what they have is a very low bandwidth signal or beacon. The signal changes to indicate key events have occurred, like parachute deployment.

It's very hard to have meaningful telemetry during the decent, because the higher link antennas can't be pointed at the host satellite correctly, and the entry can cause other interference. But this kind of low bandwidth telemetry can be enough to at least point in the right direction of what failed, and has assisted with such failure before.Phoenix, for instance, landed on the edge of uncertainty with respect to it's landing, which was traced to the parachute opening at the wrong time. This was discovered in part by these beacon signals.

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  • $\begingroup$ The ESA update says "The detailed telemetry recorded by the Trace Gas Orbiter was needed to better understand the situation." and I believe it means it received telemetry from EDM and recorded it for later transmission (since it was quite busy at the time) but I am not sure that's what it means. $\endgroup$ – uhoh Oct 20 '16 at 15:56
  • $\begingroup$ For Curiosity, This item about MELDI says "A limited amount of the data collected may be included in the real time telemetry stream during entry, but the full dataset will be transferred to the Rover Compute Element and will be transmitted to Earth within the first month after landing." $\endgroup$ – uhoh Oct 20 '16 at 15:58
  • $\begingroup$ Yeah, that sounds about right. A very limited datastream is possible, and helpful for situations like what happened, where the landing wasn't successful. $\endgroup$ – PearsonArtPhoto Oct 20 '16 at 16:01
  • $\begingroup$ "Further analysis must be done of some 600 megabytes of data Schiaparelli sent home before its signal died, to 'know whether it survived structurally or not.'" though I don't know if that's really 600 MB of actual data, or just the raw digitization (recording) of the incoming received signal on the ground $\endgroup$ – uhoh Oct 21 '16 at 0:14
  • $\begingroup$ See this comment. $\endgroup$ – uhoh Oct 21 '16 at 0:21

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