Yes, there are subtleties here that are missed by the headline. Water ice on Mars is not new, particularly in the polar ice caps. What is new is that they have produced a map of (very) near surface water ice at lower latitudes (within a few centimetres of the surface). This isn't exactly a surprise, but it also hasn't really been shown before. It shows that the water is there and widely available.

From the abstract of the article in GRL, here's a sentence on the novelty of this particular work:

> While several investigations have already predicted, identified, and characterized some properties of near‐surface ice on Mars, our results constitute a significant advance in the context of the upcoming crewed exploration because 1) they focus on very shallow depths accessible with limited equipment, 2) they provide continuous regional coverage including the mid‐latitudes, and 3) they yield moderate spatial resolution maps (3 ppd [= pixels per degree of lat/lon, I believe]) relevant to landing site selection studies.

The basic measurement used is surface thermal emission vs. time, which is inverted using a thermal model with a rock/ice depth boundary, thermal emission from the surface, albedo, solar insolation angle, conduction by a faint atmosphere, etc.

The paper also mentions that one of the co-authors passed away unexpectedly while the paper was being written. RIP.

That is exactly what I wanted to say as well. It seems every other month, I see the exact the same title. At some point, it loses it becomes just another useless news