Enlarge / A self portrait of InSight's hardware on the red planet. (credit: NASA/JPL-Caltech)

To say Mars is a bizarre planet might be something of an understatement. It has nearly no atmosphere, has an unstable liquid metal core that causes it to wobble on its axis constantly, and as a frozen desert, is an oxymoron in itself. As if Mars wasn’t strange enough, data from NASA’s InSight Lander (RIP) has now revealed that the red planet is spinning faster and faster every year.

The increasing spin went unknown until a research team found evidence of acceleration through InSight’s RISE (Rotation and Interior Structure Experiment) instrument. That same team, led by radio scientist Sebastien Le Maistre of the Royal Observatory of Belgium, who is also the principal investigator of RISE, had previously found that the core of Mars is most likely a glob of molten metal. Looking further into RISE data from InSight’s first 900 days on Mars, they saw that the planet’s spin was accelerating by a fraction of a millisecond per (Earth) year, or about 0.76 milliseconds. Martian days are gradually growing shorter. But why?

What lies beneath—or above

RISE’s main objective was to see how much Mars wobbled as its orbit was pushed and pulled by the gravity of the Sun. This would determine whether the core was more likely to be solid or liquid. However, RISE also had another task, which was measuring the length of a Martian day. Days on Mars, known as sols, are about a half-hour longer than Earth days at 24 hours and 37 minutes. RISE measured both the rotation rate and wobbling of Mars with reflected radio waves. When it received a radio signal from NASA’s Deep Space Network (DSN), it would reflect those waves right back at Earth. The difference between the frequency of the signal sent out by the DSN and the signal that bounced back to Earth told the InSight team how the lander was moving along with Mars.

Enlarge / The newly described deposits (left) have their shapes highlighted in red at right. (credit: NASA/JPL-Caltech/MSSS/IRAP )

The prodigious evidence for water on Mars has eliminated scientific debate about whether Mars had a watery past. It clearly did. But it has left us with an awkward question: What exactly did that past look like? Some results argue that there were long-lived oceans and lakes on Mars. Others argue that the water largely consisted of ice-covered bodies that only allowed water to burst out onto the surface on occasions .

The picture is further confused by the fact that some or all of these may have been true at different times or in different locations. Creating a clear picture would help shape our understanding of an environment that might have been far more conducive to life than anything that exists on present-day Mars.

A new paper describes evidence that at least one part of Mars went through many wet/dry cycles, which may be critical for the natural production of molecules essential to life on Earth—though they don't necessarily mean conditions in which life itself could thrive.

Enlarge / This view of NASA’s Ingenuity Mars Helicopter was generated using data collected by the Mastcam-Z instrument aboard the agency’s Perseverance Mars rover on Aug. 2, 2023. (credit: NASA/JPL-Caltech/ASU/MSSS)

By the standard of some of its previous flights, the most recent voyage of NASA's intrepid Ingenuity helicopter on Mars was nothing special. Over a period of 24 seconds, the small helicopter rose to an altitude 5 meters above the red planet's dusty surface and then touched back down in the same spot.

During some of its past flights, Ingenuity has flown for nearly three minutes at a time and traversed as far as 700 meters across Martian terrain. In fact, after landing on Mars more than two years ago as part of the Perseverance mission, the helicopter is arguably one of NASA's greatest exploration feats of all time.

Mission success for Ingenuity was completing five relatively short flights. However, since its first test flight in April 2021, the helicopter has exceeded all expectations by flying more than 50 different sorties across Mars and surviving long and dark winters .

Enlarge / Jezero crater shows clear signs of water-formed deposits, so it's not a surprise to find water-altered material there. (credit: NASA/MSSS/USGS )

Organic chemicals, primarily composed of carbon and hydrogen, underly all of life. They're also widespread in the Universe, so they can't be taken as a clear signature of the presence of life. That creates an annoying situation regarding the search for evidence of life on Mars, which clearly has some organic chemicals despite the harsh environment.

But we don't know whether these are the right kinds of molecules to be indications of life. For the moment, we also lack the ability to tear apart Martian rocks, isolate the molecules, and figure out exactly what they are. In the meantime, our best option is to get some rough information on them and figure out the context of where they're found on Mars. And a big step has been made in that direction with the publication of results from imaging done by the Perseverance rover.

Ask SHERLOC

The instrument that's key to the new work has a name that pretty much tells you it was designed to handle this specific question: Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC). SHERLOC comes with a deep-UV laser to excite molecules into fluorescing, and the wavelengths they fluoresce at can tell us something about the molecules present. It's also got the hardware to do Raman spectroscopy simultaneously.