#marspathfinder

Phil Stooke @PhilStooke@mastodon.social · Jul 23, 2026

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Compare this with the map published at the time. Here the tracks and images of the rover make an uninterrupted path. I really don't know why this was not done at the time. What they had was good enough, but it didn't really tell the story of the rover mission very well. Next: onwards to the Rock Garden! #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 24, 2026

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This is the 4th and last part of the Sojourner route map. The plucky little rover was driven south to avoid a group of rocks, then north again where it got stuck propped up on some rocks as we saw earlier. Finally it moved down into the rock garden area and investigated several rocks. It was moving north when it stopped to analyze Chimp, and then the mission ended - or at least the lander's ability to transmit ended. What of the rover? #maps #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 24, 2026

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The map I just posted has a white dot on it labelled 'Final position of Sojourner?' We will see where this comes from next. Sojourner was commanded from Earth (via the lander) but if it didn't hear anything for a while it was programmed to follow its path backwards to the area where it started. If it got stuck it would listen for further instructions, which never came after the lander died. So we don't know where it might have ended up. Or do we? #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 25, 2026

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We don't know what happened to Sojourner but we do have a clue. The HiRISE camera on Mars Reconnaissance Orbiter imaged the Pathfinder site early in its mission and in 2007 the camera team put out this release about the image: https://www.uahirise.org/PSP_001890_1995 on that page is this image: https://static.uahirise.org/images/2007/details/cut/manyrovers_half_annot_1lyr.jpg It shows end of drive images of the rover, and it also shows a site labelled 'Sojourner?'. My map uses that location... #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 25, 2026

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Why do they think Sojourner might be there? It's from that HiRISE image. This image is also from that HiRISE page: https://static.uahirise.org/images/2007/details/cut/MPFtopo_HiRISE_annot.jpg It shows color-coded topography and identifies a few rocks. One object seen in the image does not correspond to a rock in the panorama, so they suggest it is the rover, stranded there waiting for a command from Earth. It's not easy to match the image with the panorama but this may be right. #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 25, 2026

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Maybe that location is the final resting place of Sojourner. But suppose the mission had not ended when it did... what were people thinking about a longer extended mission for the rover? Tomorrow we will look at that question. #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 26, 2026

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The plan for Sojourner after leaving the Rock Garden was to drive back to the starting area near Yogi rock, roughly following its tracks. If it was still looking healthy the science team considered pushing out to the horizon to look at something new. But which way to go? This image, the panorama projected into a circle, gives us some ideas. Sojourner absolutely could not operate with any significant loss of radio contact - it had to remain visible from the lander. #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 26, 2026

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Look at the northern half of the image in the previous post. Rocks are silhouetted against the sky. We don't see rocks on those distant features in the southern half. To the north the horizon is only a few hundred meters away, and might be in reach. But there's something else: the landscape is pocked with depressions like The Swale and West Swale on earlier maps. Sojourner can't go into them. It's so small it would lose contact easily. #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 26, 2026

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What Sojourner needed was a close horizon with a clear path that does not drop into any hollows. If it lost contact it would wait for instructions. If none came it would backtrack until it was back in contact. It might have been possible to program it to push ahead until contact resumed, but that's dangerous - get stuck between rocks or too tilted and ground commands are essential to recover. There was one possible route... tomorrow! #mars #marspathfinder

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Phil Stooke @PhilStooke@mastodon.social · Jul 27, 2026

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Here is the suggested route for Sojourner if it had survived longer. The horizon is only a few tens of meters away, and Sojourner could not cross it and lose contact. It might have had a good closeup view or even APXS analysis of the big boulder Zaphod, and the team also hoped for a view of North Knob, a hill only partially visible from the lander, as shown in earlier maps in this set. Speaking of views... what about the rover's cameras? #maps #mars #marspathfinder