Natural satellite

Space Photos of the Week: Saturn, You So Pretty

This image, taken by NASA’s Mars Reconnaissance Orbiter, shows a landslide and rocky deposit in Simud Valles, a channel on Mars shaped by ancient floods.
1 / 7 In the latest from the Cassini mission, Saturn’s shadow on its rings shrinks as the planet tilts and orbits the sun, moving towards the planet’s solstice.NASA

The universe dished up a host of exciting new discoveries this week. From a shadow on Saturn’s rings to a murky baby…

Radical idea could restore ice in the Arctic Ocean

Melting sea ice in Barrow, Alaska
GOING, GOING… Warmer conditions in the Arctic are melting sea ice (as seen here near Barrow, Alaska). Now is the time to develop ways to save the ice, a scientist argues.

Sometimes the world needs radical ideas to correct its issues. The more out of the box the idea, the crazier the scheme, the bigger the payoff. Sometimes your answer lies beyond the borders of the world itself.

Leave it to a researcher who studies icy moons in the outer solar system to come up with an out-there scheme to restore vanishing sea ice in the Arctic.

Ice is a good insulator, says Steven Desch, a planetary scientist at Arizona State University in Tempe. That’s why moons such as Jupiter’s Europa and Saturn’s Enceladus, among others, may be able to maintain liquid oceans beneath their thick icy surfaces. On Earth, sea ice is much thinner, but the physics is the same. Ice grows on the bottom surface of floating floes. As the water freezes, it releases heat that must make its way up through the ice before escaping into the air. The thicker the ice, the more heat gets trapped, which slows down ice formation. That’s bad news for the Arctic, where ice helps keep the planet cool but global warming is causing ice to melt faster than it can be replaced.

The answer to making thicker ice more quickly? Suck up near-freezing water from under the ice and pump it directly onto the ice’s surface during the long…

Japanese Space Agency’s Mission Aims To Uncover How Moons Of Mars Formed

NASA/JPL/Handout via Reuters

The Japan Aerospace Exploration Agency (JAXA) has announced a mission to visit the two moons of Mars and return a rock sample to Earth. It’s a plan to uncover both the mystery of the moons’ creation and, perhaps, how life began in our Solar System.

The Solar System’s planets take their names from ancient Greek and Roman mythology. Mars is the god of war, while the red planet’s two moons are named for the deity’s twin sons: Deimos (meaning panic) and Phobos (fear).

Unlike our own Moon, Phobos and Deimos are tiny. Phobos has an average diameter of 22.2km, while Deimos measures an even smaller 13km. Neither moon is on a stable orbit, with Deimos slowly moving away from Mars while Phobos will hit the Martian surface in around 20 million years.

The small size of the two satellites makes their gravity too weak to pull the moons in spheres. Instead, the pair have the irregular, lumpy structure of asteroids. This has led to a major question about their formation: were these moons formed from Mars or are they actually captured asteroids?

Our own Moon is thought to have formed when a Mars-sized object hit the early Earth. Material from the collision was flung into the Earth’s orbit to coalesce into our Moon.

A similar event could have produced Phobos and Deimos. The terrestrial planets were subjected to a rain of impacts during the final throes of Solar System formation.

Mars shows possible evidence of one such major impact, as the planet’s northern hemisphere is sunk an average of 5.5km lower than the southern terrain. Debris from this or other impacts could have given birth to the moons.

Alternatively, Phobos and Deimos could be asteroids that were scattered inwards from the asteroid belt by the looming gravitational influence of Jupiter. Snagged by Mars’s gravity, the planet could have stolen its two moons. This mechanism is how Neptune acquired its moon, Triton, which is thought to have once been a Kuiper belt object, like Pluto.

There are compelling arguments for both the #TeamImpact and #TeamCapture scenario.

The orbits of the two moons are circular and in the plane of Mars’s own rotation. While the chance of this happening during a capture event are extremely low, observations of the moons suggest they may have a composition similar to that of other asteroids.

Definite determination of the moons’ composition would act as a fingerprint to distinguish the two models. A collision event…