One cycle running on two worlds

Data from MAVEN's magnetometer, Solar Wind Electron Analyzer and STATIC ion instrument showed that some Martian auroras form through a small-scale Dungey cycle. Magnetic reconnection also drives the terrestrial cycle, but without a global Martian field the process operates above localized regions of crustal magnetism.[1]

Lead author Shaosui Xu says the team expected reconnection, while the Dungey-like pattern surprised them. The result concerns one local event above a crustal magnetic region; it leaves Mars without an inferred Earth-like global magnetosphere and leaves the origins of other Martian auroras open. Agreement among three instruments strengthens that narrow claim.[1]

A null search still maps the sky

Louisa Mason of the University of Manchester searched Band 3 data from just four archival ALMA observations for narrowband technosignature candidates in two small frequency windows. None exceeded the stated thresholds. This first step at millimeter and submillimeter wavelengths reaches only those data and windows; the rest of the sky and other signal forms remain open.[2]

Galactic population modeling also suggests that earlier ALMA surveys may encompass many more stars than could be counted in the Gaia catalog, but those are model estimates rather than individually observed and verified stars. That is the value of the null result: it records which data, frequencies and thresholds were actually tested instead of announcing a discovery.[2]

Reading a finding with its instrument boundary

The two studies produce different kinds of evidence. At MAVEN, three instruments connect particle and magnetic-field behavior in one local cycle. At ALMA, archival data and stated thresholds define the scope of an absence. MAVEN measures mechanistic similarity, while ALMA measures a clearly bounded null result.[1], [2]

The next observations open in different directions across the two instrumental settings. At Mars, searching for the same local cycle above other crustal magnetic fields will show how widely the mechanism operates. For SETI, more ALMA observations, wider frequency coverage and additional signal types will enlarge the search space. Each new measurement will extend the boundary of one of these two narrow observational windows.[1], [2]