Thread: (1) This is interesting... did the Mars Express orbiter happen to photograph another (old) orbiter still circling Mars? This is a Mars Express seminar from August 21, 2020, with Prof. Ralf Jaumann, a professor at the Free University of Berlin and principal investigator...

(2) ...of the High Resolution Stereo Camera (HRSC) on Mars Express. I included a screenshot below of the object seen. Some debate on Twitter about whether it is an imaging artifact, although Jaumann doesn't think so and says it was about 20 km from Mars Express...

(3) ...There are several defunct spacecraft still orbiting Mars, but this would be unusually close.

https://www.issibern.ch/index.php/2020/08/20/mars-express

Original images are here, archived in 2018 but taken in 2017:

https://pds-geosciences.wustl.edu/mex/mex-m-hrsc-3-rdr-v3/mexhrs_1001/data/g472/