News / Science & Technology

Evidence of Martian Ocean Mounts

Comparison of exhumed delta in sedimentary rocks on Mars (left) with a modern delta on Earth (right). On the left, a shaded relief map shows elevated, branching, lobate features in Aeolis Dorsa, Mars, interpreted as resistant channel deposits that make up an ancient delta.
Comparison of exhumed delta in sedimentary rocks on Mars (left) with a modern delta on Earth (right). On the left, a shaded relief map shows elevated, branching, lobate features in Aeolis Dorsa, Mars, interpreted as resistant channel deposits that make up an ancient delta.

Related Articles

Water-Ice Clouds Activate Martian Atmosphere

There is more water vapor in the Martian atmosphere than in the upper layers of Earth's

Next Mars Rover Could Look for Signs of Past Life

NASA is thinking ahead to next rover it plans to send to Red Planet

Astronomer Finds New Moon Orbiting Neptune

An astronomer studying archived images taken by the Hubble Space Telescope finds a 14th moon orbiting the planet

Scientists Observe Solar System's Tail for First Time

Images from NASA's Interstellar Boundary Explorer spacecraft, known as IBEX, have allowed scientists to map out heliosphere's tail for first time
VOA News
Mars may have once had a vast ocean that covered as much as a third of the planet.

Researchers at the California Institute of Technology have found evidence of an ancient delta where a Martian river may have once emptied into the ocean.

"Scientists have long hypothesized that the northern lowlands of Mars are a dried-up ocean bottom, but no one yet has found the smoking gun," says Mike Lamb, an assistant professor of geology at Caltech and a coauthor of the paper describing the results. The paper was published online in the July 12 issue of the Journal of Geophysical Research.

Scientists say the evidence is not extensive enough to prove the ocean existed, but note that most of Mars’ northern hemisphere is flat and at a lower elevation than the southern hemisphere. It is similar to ocean basins found on Earth.

Using images from the Mars Reconnaissance Orbiter (MRO), Caltech scientists studied a 100-square-kilometer area on what might have been the former coastline. This area is located in a larger zone known as Aeolis Dorsa, which is covered in ridge-like features called inverted channels.

On Earth, inverted channels are the remnants of rivers or streams. After the river dries, silt and other finer materials erode away, leaving the larger rocks behind.

In the images analyzed by Caltech scientists, the inverted channels on Mars appear to fan out, which the scientists say could have been caused by three things: The channels could have been a drainage system down a mountain where they converged and created a larger river; it could have been caused by an alluvial water drainage fan; or the channels could be part of a river delta.

To determine which scenario they were looking at on Mars, scientists took pictures of the area from different points in the MRO’s orbit, creating stereo images. The camera on the MRO can distinguish changes in elevation at a resolution of one meter.

They determined that the water that once flowed through the channels was spreading out rather than converging, meaning they were part of an alluvial fan or delta. Researchers also noticed an “an abrupt increase in slope of the sedimentary beds near the downstream end of the channels,” which is commonly seen when a stream empties into a large body of water. 

Deltas have been observed on Mars before, but most are inside a geological boundary like a crater. The newly discovered delta showed no confining boundary.

"This is probably one of the most convincing pieces of evidence of a delta in an unconfined region — and a delta points to the existence of a large body of water in the northern hemisphere of Mars," said Roman DiBiase, a postdoctoral scholar at Caltech and lead author of the paper.

But scientists are quick to point out that there could be other explanations. For example, there could have been a confining boundary that later disappeared due to geological activity, but that would lead to the conclusion that the Martian surface was more geologically active than previously thought.

Further analysis of the hypothetical coastline will be needed before determining if there was a large ocean.

"In our work and that of others — including the Curiosity rover — scientists are finding a rich sedimentary record on Mars that is revealing its past environments, which include rain, flowing water, rivers, deltas, and potentially oceans," Lamb said. "Both the ancient environments on Mars and the planet's sedimentary archive of these environments are turning out to be surprisingly Earth-like."

You May Like

EU Court Fines Poland for Hosting CIA 'Black Sites'

Ruling is first time a court has acknowledged suspects were held and tortured at the sites, under US program launched following the 9/11 terrorist attacks More

Migrant Issues Close to Home Spur Groups to Take Action

Groups placing water, food in the desert, or aiding detainees after release, have one common goal: no more deaths of migrants crossing illegally into the US More

Video At AIDS Conference, Prevention Pill Stirs Excitement

Truveda shows promise, spurring debate over access and other approaches More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Israel Targets Gaza Supply Tunnelsi
X
July 24, 2014 4:42 AM
The Israeli military has launched a ground operation in Gaza to destroy the myriad tunnels that may have been used to smuggle weapons to Hamas. VOA's Zlatica Hoke reports that could mean more hardship for the people of Gaza, who obtain some of their essential supplies through these underground passages
Video

Video Israel Targets Gaza Supply Tunnels

The Israeli military has launched a ground operation in Gaza to destroy the myriad tunnels that may have been used to smuggle weapons to Hamas. VOA's Zlatica Hoke reports that could mean more hardship for the people of Gaza, who obtain some of their essential supplies through these underground passages
Video

Video MH17's 'Black Boxes' Could Reveal Crash Details

The government of Malaysia now has custody of the cockpit voice and flight data recorders from Malaysia Airlines Flight 17, which was hit by a missile over Ukraine before crashing last week. As VOA's Carolyn Presutti reports, the so-called black boxes may hold information about the final minutes of the flight.
Video

Video Living in the Shadows Panel Discussion

Following a screening of the new VOA documentary, "AIDS - Living in the Shadows," at the World AIDS conference in Melbourne, a panel discussed the film and how to combat the stigma associated with HIV/AIDS.
Video

Video IAEA: Iran Turns its Enriched Uranium Into Less Harmful Form

Iran has converted its stockpiles of enriched uranium into a less dangerous form that is more difficult to use for nuclear weapons, according to the United Nations’ Atomic Energy Agency. The move complies with an interim deal reached with Western powers on Iran's nuclear program last year, in exchange for easing of sanctions. Henry Ridgwell reports for VOA from London.
Video

Video Relic of Saint Draws Catholics Worried About Immigration Issue

A Roman Catholic saint who is a figure of devotion for those crossing the border into the United States is attracting believers concerned about the plight of undocumented immigrants. Mike O'Sullivan reports from Los Angeles, where a relic of Saint Toribio has drawn thousands to local churches.
Video

Video US Awards Medal of Honor for Heroics in Bloodiest of Afghan Battles

U.S. combat troops are withdrawing from Afghanistan, on pace to leave the country by the end of this year. But on Monday, U.S. President Barack Obama took time to honor a soldier whose actions while under fire in Afghanistan earned him the Medal of Honor. VOA's Jeff Seldin has more from the Pentagon.
Video

Video Ukraine Rebels Surrender MH17 Black Boxes

After days of negotiations, a senior separatist leader handed over two black boxes from an airliner downed over eastern Ukraine to Malaysian experts early Tuesday. While on Monday, the U.N. Security Council unanimously demanded that armed groups controlling the crash site allow safe and unrestricted access to the wreckage.
Video

Video In Cambodia, HIV Diagnosis Brings Deadly Shame

Although HIV/AIDS is now a treatable condition, a positive diagnosis is still a life altering experience. In Cambodia, people living with HIV are often disowned by friends, family and the community. This humiliation can be unbearable. We bring you one Cambodian woman’s struggle to overcome a life tragedy and her own HIV positive diagnosis.

AppleAndroid