Image: Ancient "bomb sag" crater on Mars
NASA/Georgia Tech
The arrow points to an ancient "bomb sag" on Mars, a crater produced when a Martian rock blasted into the air by a volcanic eruption 3.5 billion years ago fell back to the ground.
updated 5/9/2012 9:07:14 PM ET 2012-05-10T01:07:14

A new look at an ancient volcanic blast on Mars suggests that the Red Planet was much more Earth-like billions of years ago, with abundant surface water and a relatively thick atmosphere, scientists say.

The air on Mars was likely at least 20 times denser 3.5 billion years ago than it is today, researchers said. Back then, they added, the Red Planet's atmosphere likely helped sculpt and shape the planet's surface, much like Earth's atmosphere does today.

"Atmospheric pressure has likely played a role in developing almost all Mars’ surface features," said study lead author Josef Dufek, of the Georgia Institute of Technology, in a statement. "The planet’s climate, the physical state of water on its surface and the potential for life are all influenced by atmospheric conditions."

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Currently, the atmosphere of Mars is less than 1 percent as thick as that of the Earth.

Recreating Martian volcanoes in the lab
The new study was inspired by a rock fragment blasted into the Martian atmosphere by a volcanic eruption roughly 3.5 billion years ago. This rock fell back to Mars, creating a divot, or "bomb sag," in the volcanic sediment. [Photos: The Search for Water on Mars]

In 2007, NASA's Spirit rover took a closer look at the embedded fragment, giving Dufek and his colleagues enough information to determine the size, depth and shape of the bomb sag.

The team then went to the lab to generate some bomb sags of their own. They created beds of sand using grains the same size as those observed by Spirit, then launched particles of varying composition at different speeds into the beds.

Some of the sand beds were dry, some were damp and some were saturated. Whatever their composition, particles propelled into the saturated beds consistently produced bomb sags similar to the one Spirit studied on Mars, researchers said.

The team also determined that lab particles must hit the wet sand at a speed less than 90 mph or so to create penetration depths similar to the Martian bomb sag.

A thicker Martian atmosphere?
In order for a rock to move at such speeds through Mars' atmosphere, the air would have to be at least 20 times more dense there than it is today, researchers said.

"Our study is consistent with growing research that early Mars was at least a transiently watery world with a much denser atmosphere than we see today," Dufek said. "We were only able to study one bomb sag at one location on the Red Planet. We hope to do future tests on other samples based on observations by the next rover, Curiosity."

NASA's 1-ton Curiosity rover is due to land at the Red Planet's Gale Crater on the night of Aug. 5. Curiosity's main task is to determine if the Gale Crater area is, or ever was, capable of supporting microbial life.

Dufek and his colleagues published their results recently in the journal Geophysical Research Letters.

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Photos: Month in Space: January 2014

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  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
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