2hats
Dust.
That's what the press release says:
Source: NASA.
Speculation is that this concerns evidence for water on Mars (given the background of some of the panel members for this event).
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.
Source: NASA.
Speculation is that this concerns evidence for water on Mars (given the background of some of the panel members for this event).