“Mars Has Water!” News Releases
This table is updated often. The latest update is the date of the latest news release.
|Date News Released||News Title, Mission, Evidence
||Reliability of Evidence||Amount of Water||Date the Water May Have Been Liquid|
|September 24, 2009||Scientists See Water Ice in Fresh Meteorite Craters on Mars , HiRISE Camera on Mars Reconnaissance Orbiter, images and change in images over time. Very pure water ice found at mid-low latitudes on Mars was kicked up (excavated) when a meteor hit Mars creating a crater. This ice disappeared quickly over the course of the summer.||Medium||Small||A long time ago. The ice probably sublimed rather than melting.|
|September 29, 2008||NASA Mars Lander Sees Falling Snow, Soil Data Suggest Liquid Past , MET on Phoenix, LIDAR data on polar clouds||Medium||Small||Ice crystals that sublimed before hitting the surface|
|September 24, 2008||Evidence of Rain on Mars , HRSC on Express, MOC on Global Surveyor, HiRISE and CTX on MRO, Photograph of river channels and other water-eroded surface features||Medium||Medium||3.5-3.8 Billion Years Ago|
|July 31, 2008||NASA Spacecraft Confirms Martian Water, Mission Extended , Phoenix Lander, Direct Sampling and Gas Analysis||Extremely High||Small||Well, we melted it in TEGA, but other than that, unknown|
|May 30, 2008||NASA’s Phoenix Lander Robotic Arm Camera Sees Possible Ice , Phoenix Lander, Photograph of Ice followed by Photograph of Presumed Ice Sublimation ||Medium||Small||Unknown|
|Dec. 6, 2006||NASA Images Suggest Water Still Flows in Brief Spurts on Mars , Mars Global Surveyor, Formation of new gullies in crater walls||High||Small||Between 1999 and 2005|
|May 28, 2002 (2001?)||Found it! Ice on Mars , Mars Odyssey, Large Amounts of Subsurface Hydrogen||Low||Large||Unknown: millions of years ago.|
|June 22, 2000||Mars Surprise , Mars Global Surveyor, Old Gullies||High||Small||In the last million years or last 100 years.|
|1999||Water on Mars: Not So Ancient, After All , Mars Global Surveyor, Large-Scale Landforms Possibly Created by Water||Medium||Medium||In the last 10 million years|
|1970s||North Pole Has Some Water Ice  as well as Dry CO2 Ice , Mariner 9 and Earth-Based Observations, Spectrographic and Infrared Analysis||Medium||Very Small||Unknown: millions of years ago.|
From December 8, 2006
The Mars Global Surveyor, a satellite that has been in orbit around Mars since 1997, sent back a picture containing evidence that water flowed on Mars sometime during the last five years. These pictures were released by NASA on December 6, 2006, though the photos were taken in 2004 and 2005.
The evidence shows new deposits within a crater that look like they were left by flowing water. Simple enough evidence, so let me answer a few specific questions about this story.
How come we’re just hearing about this now?
As of November 2006 the Mars Global Surveyor stopped responding to NASA Control (it had a lifetime of 9 years – 7 years longer than expected). The pictures containing the evidence were taken and sent to Earth in 2004 and 2005. As with most NASA missions, we get more data back than we can possibly sift through as fast the satellites send it to us. To tell you the truth, they’re still sorting through some of the data from the 1996 Pathfinder mission to Mars (the first rover). Expect to hear more discoveries from the Mars Global Surveyor in the future, even though the satellite itself is now defunct.
Background Knowledge: Erosion and Deposition
Okay, time for a quick geology/planetology class. Do you remember the vocabulary words sediment, erosion, and deposition from some science class you had? As water flows it picks up (erosion) bits of dirt and whatever else is on the surface (sediments). When the water slows down it drops those sediments (deposition).
Water is the best eroder we know. Wind can erode too, but not nearly as effectively, and wouldn’t leave sediments in the same patterns as water. That’s why we’re excited by these new photos: the deposits look like they were left by water.
Why is this important?
Life as we know it needs liquid water. Life is cool.
Is this news?
“Wait,” I hear you saying, “Didn’t this news come out several years ago? And then didn’t we hear it again a couple of years ago? What’s with this?”
You’re right: this is the fourth (or maybe fifth) reliable announcement in recent history that “Mars has water.” The difference between all these announcements is the strength of the evidence, the amount of water found, and the estimated date that the water was liquid.
In the 1970s, we observed the light bouncing off Mars’s ice caps, and determined that they contained at least some water, though they were mostly frozen carbon dioxide (dry ice). Two decades later, in 1999, we were able to look at photos of the surface of Mars that showed outlines of riverbeds, floodplains, and smooth surfaces: all evidence of “recent” water activity. In this case, “recent” means geologically speaking: within several million years. In the year 2000, scientists received pictures of gullies carved by water: gullies that could have easily been formed within the last 100 years. Or, they could have been formed a million years ago, since we haven’t observed much erosion on Mars.
More recently, in 2001 (2002?), scientists detected large amounts of underground hydrogen. Since water is H2O (two hydrogens and an oxygen), underground hydrogen indicates the possibility of large deposits of water. Other evidence tells us that this water would be frozen, if it’s actually there.
Two days ago we got new news. Between the time that we took a picture of a few certain crater walls in 1999, and the most recent pictures of the same craters from 2004 and 2005, new dirt (the fancy word for dirt on another planet is regolith) had been deposited.
Where’d I Get My Info?
Mars Global Surveyor 
Press Release 
Press Release 
Space Science