For about the past 30 months, the Opportunity rover has been exploring Cape Tribulation on Mars, a towering ridge on the rim of Endeavour crater. Now, Opportunity has finally left that location, to continue its journey southward down the western side of the crater rim. The views have been scenic from the top of Cape Tribulation, but now it is time to move on, and head to the next major target, an ancient gully not too far to the south-east, also on the crater rim. This gully is thought to have been carved by running water millions or billions of years ago, so scientists are very interested in examining it up close, and the rover is now almost there.
With thousands of images taken by various probes sent to Mars, it would seem inevitable that unusual or puzzling objects might be seen in some of them. And of course, there have been, most notably the famous “Face on Mars” first seen in low-resolution Viking orbiter images in the 1970s. Higher-resolution images taken later by other orbiters with better cameras showed it, and nearby interesting formations, to be just natural hills and mesas. Despite that, other curious things are seen in both orbital and ground images from time to time, although they almost always have a simple prosaic explanation. Another such oddity was just recently seen in an image taken by the Mars Reconnaissance Orbiter (MRO), which has attracted some attention. Most likely it is a natural rock formation, but it’s also not, as described by the tabloid Daily Mail, a “spherule” either.
As the Curiosity rover continues its traverse among the buttes and sand dunes of Gale crater, you would expect to see some wear and tear after a few years. The rover’s wheels have naturally taken the brunt of that, with small dents and holes appearing in the solid aluminum. But now, new damage has been seen for the first time, breaks in the raised treads on the wheels, called grousers. While not unexpected, and not a mission-stopper by any means, it does show how the wheels, and the rover overall, have been aging since landing in 2012.
Mars is a busy place these days, with multiple rovers and orbiters exploring the planet. Out of the several spacecraft currently in orbit, NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) is a fairly recent addition, having been at Mars for just over two years now. Usually, things are pretty routine, but this week the spacecraft had to make an unplanned evasive maneuver – to avoid a collision with one of Mars’ two small moons, Phobos!
The subject of water on Mars is one of the most highly debated in planetary science; various missions have provided ample evidence that the planet used to be a lot wetter than it is now, with rivers, lakes and maybe even oceans. Most scientists now generally agree on this, but as to how much water there was, how long it lasted and how warm the environment was, is another question. There have been apparent conflicting lines of evidence, and now findings from the Curiosity rover have only added to the mystery. Curiosity has revealed a paradox of sorts – it has found abundant evidence for ancient lakes in now-dry Gale crater, but at the same time has not found evidence for a previous thicker atmosphere with more carbon dioxide, which normally would be needed for water to remain liquid on the surface. These two lines of evidence seem to contradict each other, so how to resolve this puzzle?
Thirteen years. That is how long NASA’s Opportunity rover has now been exploring Meridiani Planum on Mars; not bad for a robot which was designed with a hoped-for nominal 90-day mission. Today marks the 13th anniversary of the landing of Opportunity, on Jan. 24, 2004 PST (Jan. 25, 2004 UTC). The mission since then has been nothing short of incredible, as Opportunity soon found evidence that Meridiani Planum used to be a much wetter place than it is now. It was a place where microbial life could have existed; whether it actually did or not is still unknown but Opportunity continues to provide more clues as it continues exploring vast sandy plains and mountainous crater rims.