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Perseverance (2021) and Curiosity (2012) each ejected, among many other things, two tungsten "cruise balance masses" before reaching Mars's atmosphere, each about 70 kg.

Were their impacts on the surface noticeable, either by craters visible from orbiting cameras, or by Insight's seismometer?

Some sizeable fragments should have reached the surface intact:

  • Tungsten's melting point is 3700 K, while Perseverance's heat shield encountered at most 2400 K.
  • Tungsten is twice as dense as the nickel-iron meteors that penetrate even Earth's atmosphere.

They would hit the surface at a speed not much less than the approach speed of 5 km/s; the full 70 kg would pack a wallop of almost a gigajoule, about half of "the kinetic energy of a Airbus A380 at cruising speed" per Jalopnik.

Seismometers recorded on 2007 Sept 15 a 17 GJ meteorite impact in Peru whose crater was 14 m wide, so it seems plausible that a 1 GJ impact would be both seismographically noticeable (Mars is much more quiescent than Peru) and visible (MRO never ceases to amaze).

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    $\begingroup$ Yes, they definitely hit Mars. I'm seeing a lot of information about the Insight team planning for detecting the impacts from late January/Early February, haven't found anything about them successfully doing so. $\endgroup$ – notovny Mar 9 at 1:36
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    $\begingroup$ @notovny That's great! In which case you have an excellent answer for How could InSight's seismometers be intentionally and meaningfully “pinged”? $\endgroup$ – uhoh Mar 9 at 2:06
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    $\begingroup$ I'm no rocket scientist; caveat emptor! Yes Horizons has it all the way down to the surface, so if we had an exact UTC time for the release we could have the altitude and position & velocity vectors for those "lead zeppelins". $\endgroup$ – uhoh Mar 9 at 4:53
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    $\begingroup$ photos from Mars Reconnaissance Orbiter show the impact sites from Curiosities 2 main ballast weights about 80k from the rover plus the impact sites of the 6 smaller weights jettisoned just before separation....I guess its fair to assume Perseverance's ballast weights would be a similar distance.nasa.gov/mission_pages/MRO/multimedia/… $\endgroup$ – giles tester Mar 9 at 8:01
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    $\begingroup$ @gilestester I think that can be posted as at least a partial answer. Question asks "...either by craters visible from orbiting cameras..." and that's exactly what's shown there. $\endgroup$ – uhoh Mar 18 at 23:08
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Photos from Mars Reconnaissance Orbiter show the impact sites from Curiosity's 2 main ballast weights about 80 km from the rover, plus the impact sites of the 6 smaller weights jettisoned just before separation...

I guess its fair to assume Perseverance's ballast weights would be a similar distance. https://www.nasa.gov/mission_pages/MRO/main/index.html

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    $\begingroup$ The link is pretty general, it's just an index to many, many other pages. Can you add the link to the particular page that you'd like to cite as supporting your answer? Thanks! $\endgroup$ – uhoh Mar 28 at 12:05

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