Timeline for How hard is it to receive direct signals from vehicles on the surface of Mars, and has anyone other than the DSN done so?
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
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| Mar 6, 2021 at 12:50 | comment | added | user21103 | @uhoh: which is good! | |
| Mar 6, 2021 at 5:44 | comment | added | uhoh | I think our conclusions are similar: space.stackexchange.com/a/50575/12102 | |
| Mar 5, 2021 at 13:32 | history | edited | user21103 | CC BY-SA 4.0 |
added link to goonhilly blog
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| Mar 2, 2021 at 11:33 | vote | accept | CommunityBot | ||
| Mar 1, 2021 at 10:35 | comment | added | user21103 | @user2705196: yes, I think it would be millions of dollars (maybe even less) not billions: it's kind of a house-sized thing really. I was just trying to think of very rich people! The real trick would be to find a surplus one for cheap, which is more-or-less what the Goonhilly people have done, | |
| Mar 1, 2021 at 10:33 | comment | added | user21103 | @JohnBollinger: I rearranged my (*) equation to get this crappy $K$ thing, which is the value of $P_td^2D^2$ for something to be just detectible. By assumption Scot Tilley was working at that value, and we know all the LHS for that, which gives us $K$, which involves his value of $D$. Then if we have other values for $P_t$ & $d$, we can work out the required $D$ using the $K$ we worked out. | |
| Mar 1, 2021 at 2:30 | comment | added | uhoh | @JohnBollinger "Scott Tilley was just able to hear MRO" and that satellite's much larger diameter and therefore higher gain antenna and higher power. When scaling to the much lower gain antenna and lower power that a rover has, the receive antenna must be scaled up by the same cumulative factor. | |
| Feb 28, 2021 at 16:51 | comment | added | John Bollinger | You lost me somewhere in that computation. How is it that the size of Tilly's dish is an input parameter, but you conclude that a much larger dish than Tilly's is needed to receive the signal? Or is that in fact not how this answer should be read? | |
| Feb 28, 2021 at 15:48 | comment | added | user2705196 | Great answer! Which made me think, how expensive would it be to build a 10m dish?? Naively, I'd think much less than Bezos, Gates, or Musk kind of money. | |
| Feb 28, 2021 at 13:33 | history | edited | user21103 | CC BY-SA 4.0 |
Noted that Goonhilly officially did hear the vehicle during descent and on the surface.
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| Feb 28, 2021 at 11:22 | comment | added | user21103 | @jamesqf: yes, there's a sourced figure of 100W for MRO, and I assumed 33W for Perseverance. I suspect it is less than that but I wanted to make it more likely to hear it in my sums. | |
| Feb 28, 2021 at 4:26 | comment | added | jamesqf | Not only do the orbiting relays have larger antennas, they are also likely to have more power available, since they can have larger solar panels that don't get dusty, don't have to worry about nights, and don't have to use power for wheels, robotic arms, and the like. | |
| Feb 27, 2021 at 19:16 | comment | added | uhoh |
+1 for a wonderful answer! Since even at closest approach Mars is much smaller than the resolution of even a 100 meter dish at 8 GHz any time you point at Mars you get everything, and have to use your radio to reject all the spacecraft except the one you want to listen to. It's possible space agencies hear other space agency's Mars craft regularly.
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| Feb 27, 2021 at 17:35 | comment | added | Organic Marble | That was really interesting and thanks for the link to the goonhilly site. At first I was hoping the initial antenna was named after Arthur Clarke but it seems to be the king instead. | |
| Feb 27, 2021 at 16:02 | history | answered | user21103 | CC BY-SA 4.0 |