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

Video VOA EXCLUSIVE: Iraq President Vows to Fight IS 'Until They Are Killed or We Die'

In wide-ranging interview with VOA Persian service reporter, Fuad Masum describes conflict as new type of fight that will take time to win More

Video Russian Anti-Corruption Campaigner Slams Putin’s Crackdown on Dissent

In interview with VOA Alexei Navalny says he believes new law against 'undesirable NGOs' part of move to keep Russian president in power More

Video On The Scene: In Ethiopia, 'Are You a Journalist?' Is a Loaded Question

VOA's Anita Powell describes the difficulties faced by reporters in fully conveying the story in a country where people are reticent to share their true opinions More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Expelled from Pakistan, Afghan Refugees Return to Increased Hardshipi
X
Ayesha Tanzeem
May 28, 2015 6:48 PM
Undocumented refugees returning to Afghanistan from Pakistan have no jobs, no support system, and no home return to, and international aid agencies say they and the government are overwhelmed and under-resourced. Ayesha Tanzeem has more from Kabul.
Video

Video Expelled from Pakistan, Afghan Refugees Return to Increased Hardship

Undocumented refugees returning to Afghanistan from Pakistan have no jobs, no support system, and no home return to, and international aid agencies say they and the government are overwhelmed and under-resourced. Ayesha Tanzeem has more from Kabul.
Video

Video Britain Makes Controversial Move to Crack Down on Extremism

Britain is moving to tighten controls on extremist rhetoric, even when it does not incite violence or hatred -- a move that some are concerned might unduly restrict basic freedoms. It is an issue many countries are grappling with as extremist groups gain power in the Middle East, fueled in part by donations and fighters from the West. VOA’s Al Pessin reports from London.
Video

Video Floodwaters Recede in Houston, but Rain Continues

Many parts of Texas are recovering from one of the worst natural disasters to hit the southwestern state. Heavy rains on Monday and early Tuesday caused rivers to swell in eastern and central Texas, washing away homes and killing at least 13 people. As VOA’s Greg Flakus reports from Houston, floodwaters are receding slowly in the country's fourth-largest city, and there likely is to be more rain in the coming days.
Video

Video 3D Printer Makes Replica of Iconic Sports Car

Cars with parts made by 3D printers are already on the road, but engineers are still learning about this new technology. While testing the possibility of printing an entire car, researchers at the U.S. Department of Energy recently created an electric-powered replica of an iconic sports roadster. VOA’s George Putic has more.
Video

Video Al-Shabab Recruitment Drive Still on In Kenya

The al-Shabab militants that have long battled for control of Somalia also have recruited thousands of young people in Kenya, leaving many families disconsolate. Mohammed Yusuf recently visited the Kenyan town of Isiolo, and met with relatives of those recruited, as well as a many who have helped with the recruiting.
Video

Video US Voters Seek Answers From Presidential Candidates on IS Gains

The growth of the Islamic State militant group in Iraq and Syria comes as the 2016 U.S. presidential campaign kicks off in the Midwest state of Iowa.   As VOA’s Kane Farabaugh reports, voters want to know how the candidates would handle recent militant gains in the Middle East.
Video

Video A Small Oasis on Kabul's Outskirts Provides Relief From Security Tensions

When people in Kabul want to get away from the city and relax, many choose Qargha Lake, a small resort on the outskirts of Kabul. Ayesha Tanzeem visited and talked with people about the precious oasis.
Video

Video Film Festival Looks at Indigenous Peoples, Culture Conflict

A recent Los Angeles film festival highlighted the plight of people caught between two cultures. Mike O'Sullivan has more on the the Garifuna International Film Festival, a Los Angeles forum created by a woman from Central America who wants the world to know more about her culture.
Video

Video Kenyans Lament Losing Sons to al-Shabab

There is agony, fear and lost hope in the Kenyan town of Isiolo, a key target of a new al-Shabab recruitment drive. VOA's Mohammed Yusuf visits Isiolo to speak with families and at least one man who says he was a recruiter.
Video

Video Scientists Say Plankton More Important Than Previously Thought

Tiny ocean creatures called plankton are mostly thought of as food for whales and other large marine animals, but a four-year global study discovered, among other things, that plankton are a major source of oxygen on our planet. VOA’s George Putic reports.
Video

Video Kenya’s Capital Sees Rise in Shisha Parlors

In Kenya, the smoking of shisha, a type of flavored tobacco, is the latest craze. Patrons are flocking to shisha parlors to smoke and socialize. But the practice can be addictive and harmful, though many dabblers may not realize the dangers, according to a new review. Lenny Ruvaga has more on the story for VOA from Nairobi, Kenya.
Video

Video Iowa Family's Sacrifice Shaped US Military Service for Generations

Few places in America have experienced war like Waterloo. This small town in the Midwest state of Iowa became famous during World War II not for what it accomplished, but what it lost. As VOA’s Kane Farabaugh reports, the legacy of one family’s sacrifice is still a reminder today of the real cost of war for all families on the homefront.

VOA Blogs