UPDATE 8/4, 3:15pm: It appears that NASA will answer the rumors tomorrow at a press conference. Don't get your hopes up: the early information available suggests that the most likely outcome of the new data is to downgrade the habitability of Martian soil. See our new post on the topic.

Rumors are flying this weekend that Mars Phoenix has made a major discovery relating to the potential for life on Mars.

Wired.com reached Sam Kounaves, the mission's wet-chemistry lab lead, by cellphone this morning. He quickly directed us to speak with NASA's PR representatives, but not before he said, simply, "Rumors are rumors."

They stem from an article in Aviation Week and subsequent pickup on Slashdot and elsewhere indicating that the White House had been briefed on the potential for life on the planet.

"The White House has been alerted by NASA about plans to make an announcement soon on major new Phoenix Lander discoveries concerning the "potential for life" on Mars," wrote Craig Covault, citing anonymous sources on the Phoenix Lander's wet-chemistry lab team.

Covault's article showed some restraint, though, and made sure to note that "sources say the new data do not indicate the discovery of existing or past life on Mars."

The subtleties, however, were quickly lost in the blogosphere, where excitement began to build that simple extraterrestrial life, or something suggesting its presence, had been found on Mars.

Late last night, @MarsPhoenix (aka Veronica McGregor, a NASA employee) responded to the story, via the mission's Twitter account.

"Heard about the recent news reports implying I may have found Martian life. Those reports are incorrect," she Tweeted. "Reports claiming there was a White House briefing are also untrue and incorrect."

Covault implies that a test in which Earth water was mixed with Martian soil is the cause of the excitement. Mars Phoenix scientists have repeatedly stated that the lander doesn't have the tools to directly detect life.

Over at LiveScience, David Leonard hints, without sourcing or attribution, that a paper on the work is going to come out in the journal Science.

"The reason that all this seems so hush-hush is due to a future paper and press release that appears likely to pop out of the American Association for the Advancement of Science (AAAS) and its Science magazine," Leonard writes. "Whatever the poop is from the scoop that’s been studied by Phoenix, that information is purportedly going through peer-review."

We're still trying to get to the bottom of this story and will keep you updated with any new developments.

UPDATE #2 Monday, 11:02am: We contacted the president's science advisor's office and his spokesperson, Kristin Scuderi, said, "No one was briefed by NASA about any science reports from the Mars Phoenix team." She referred specifically to John Marburger, the director of the Office of Science and Technology Policy, and Richard Russell, the organization's associate director.

There is another denial out now on Space.com from Peter Smith, the mission's lead, who called the information about a White House briefing "bogus and damaging." (Damaging to whom, one wonders.) In a subsequent email Smith said that he didn't know "where this information came from." Craig Covault, the veteran space writer who authored the original article in Aviation Week, is sticking by his story.

Also, over at the Discovery Channel's Space Disco blog, Dave Mosher reports that a Mars Phoenix scientist, Chris Hecht, emailed him about the rumors. "There is likely to be a press release to address them, possibly as soon as tomorrow," the scientist wrote.

So, the story isn't over, but it's not any clearer, either.

UPDATE #1 Sunday, 12:10pm: Check out the forum discussion taking place onunmannedspaceflight.com. There is a lot of commentary about how Covault did his reporting and what kinds of discoveries the Phoenix Lander's various instruments are capable of making. (Hat tip to NASA Watch's Keith Cowing for pointing them out.)

WiSci 2.0: Alexis Madrigal's Twitter , Google Reader feed, and webpage; Wired Science on Facebook.