UPDATE!
NASA’s live stream is down (for configuration errors) but Nature Geoscience has released this paper from embargo. (Probably water on the brain)
Spectral evidence for hydrated salts in recurring slope lineae on Mars
Looks like the earlier speculation was correct.
NASA is hyping an announcement to be made tomorrow about Mars.
NASA to Announce Mars Mystery Solved
NASA will detail a major science finding from the agency’s ongoing exploration of Mars during a news briefing at 11:30 a.m. EDT on Monday, Sept. 28 at the James Webb Auditorium at NASA Headquarters in Washington. The event will be broadcast live on NASA Television and the agency’s website.
News conference participants will be:
- Jim Green, director of planetary science at NASA Headquarters
- Michael Meyer, lead scientist for the Mars Exploration Program at NASA Headquarters
- Lujendra Ojha of the Georgia Institute of Technology in Atlanta
- Mary Beth Wilhelm of NASA’s Ames Research Center in Moffett Field, California and the Georgia Institute of Technology
- Alfred McEwen, principal investigator for the High Resolution Imaging Science Experiment (HiRISE) at the University of Arizona in Tucson
A brief question-and-answer session will take place during the event with reporters on site and by phone.
It will probably be connected with this paper to be presented this week at the European Planetary Science Congress. Three of the authors are to be at the Press Announcement. Even if not specifically about this paper the announcement is likely to be about water on Mars.

Recurring slope lineae observed in HiRISE images of Mars. The RSL form on Sun facing slopes during warm season and fade during cold season. image sci-news.com
L Ojha et al, Spectral Evidence for Hydrated Salts in Seasonal Brine Flows on Mars, Vol. 10, EPSC 2015-838-1, 2015 European Planetary Science Congress 2015
Abstract: Recurring Slope Lineae (RSL) are seasonal flows on warm Martian slopes initially proposed, but not confirmed, to be caused by briny water seeps. Here we report spectral evidence for hydrated salts on RSL slopes from four different RSL locations from the Compact Reconnaissance Imaging Spectrometer for Mars on board Mars Reconnaissance Orbiter. These results confirm the hypothesis that RSL are due to present-day activity of briny water.
It would suggest that the dark streaks observed periodically on the surface of Mars are caused by the seasonal flow of salt-laden water across the surface. The salt levels would have to be high enough to allow the water to remain liquid long enough to create the streaks before it freezes. Some of the streaks seem to be of the order of several hundred metres in length.
If there actually is sub-surface ice on Mars, then it is not an unthinkable geo-engineering step (terraforming) to achieving a Martian atmosphere which, in time, could contain free oxygen in addition to water vapour and carbon dioxide. It is still not clear how Earth got its Nitrogen which provides a stable ballast and it is unclear if a similar “ballast gas” could be engineered around Mars.
The paper continues:
Pure water would rapidly evaporate and/or freeze on the present-day surface of Mars at most times and places; however brines are far less volatile compared to pure water due to their lower freezing points and evaporation rates. Various salts (e.g. sulfates, chlorides and perchlorates) have been detected on the surface of Mars from remote and in situ investigations. These salts can lower the freezing point of water by up to 80 K, lower the evaporation rate of water by an order of magnitude, and can be hygroscopic (i.e. able to easily absorb atmospheric moisture), thus increasing the possibility of forming and stabilizing liquid water on the surface of present day Mars. Recurring Slope Lineae (RSL) are narrow, low reflectance features forming on present-day Mars that have been hypothesized to be due to the transient flow of liquid water. ….
and concludes:
The origin of water forming the RSL is not understood, given the extreme aridity of Mars’ surface environment. Water could form by the surface/sub-surface melting of ice, but the presence of near-surface equatorial ice is highly unlikely. Water could also form via deliquescence by hygroscopic salts, although it is unclear how the Martian atmosphere can sufficiently supply water vapor every year to create RSL. The absence of concentrated deliquescent salts would rule out this hypothesis. Another hypothesis is seasonal discharge of a local aquifer, which concentrates salt deposits as the brine evaporates, but then lineae emulating from the tops of local peaks are difficult to explain. It is conceivable that RSL are forming in different parts of Mars via different formation mechanisms. The new compositional insights reported here from widely separated sites provide essential new clues.
Water on Mars not only gives a higher probability of some life-form having existed, or existing, on Mars but also increases the probability of human life coming to exist on Mars. That would be something to be around for, but it will be after I am long gone.