Aliens haven't landed—the flying saucer seen in this April 9 picture belongs to NASA, not invaders from Mars.

In fact, the saucer is planned for an earthly invasion of Mars. The rocket-powered test vehicle belongs to the space agency's Low-Density Supersonic Decelerator (LDSD) project, an effort to test better supersonic parachutes and high-altitude landing brakes for future Mars explorers.

On display this week at NASA's Jet Propulsion Lab, the device will be fired from Hawaii this summer, almost into space, to undertake a series of tests aimed at safely delivering heavier cargoes, and astronauts, to the red planet someday.

View Images PHOTOGRAPH BY NASA/JPL/UNIVERSITY OF ARIZONA

High-flying winds on Mars lead to twin-toned dunes, seen in this Mars Reconnaissance Orbiter image released on April 9.

The HiRISE camera aboard the orbiter sees into the infrared spectrum, revealing the dual coloring of the dunes located in the Meridiani Terra region of Mars.

Rusty, light-colored dust coats the lower-lying folds of the dunes. That's because they are left unmolested by fierce winds that flow at higher altitudes. (See "Pictures: Looking Back at Visions of Life on Mars.")

Higher up on the dunes, the winds scour their surfaces, removing the dust and revealing the dark blue sands underlying the dune crests.

View Images PHOTOGRAPH BY Christoph Malin, ESO

High above the Chilean Andes, a fireball zooms past the high-precision antennas of a desert space observatory, as seen in this April 7 time-lapse picture released by the European Southern Observatory.

The shooting star is just a bit of space dust burning up as it zips through the upper atmosphere, leaving a fiery wake. (See "Star Found Shooting Water 'Bullets.'")

Beneath the meteor, some of the 66 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) observatory keep an eye on far more distant space phenomena from their perch some 16,404 feet (5,000 meters) above sea level.

Just above the antennas, in the center of the image, Mars and the star Spica, the brightest star in the constellation Virgo, burn brightly in the night sky.

View Images PHOTOGRAPH BY NASA/JPL/UNIVERSITY OF ARIZONA

Just outside an ancient volcano, this curious heart-shaped feature rears above the Martian plain, as seen in an April 9 view by NASA's HiRISE camera.

Most likely, the ridges enfolding the mount reveal that it's a long-dormant, dusted-over volcanic vent. Winds eroded the softer rocks surrounding the vent ridges, leaving only fortress-like walls behind. (See "Strange Lights in Mars Photos Are Not Alien Bonfires.")

Such "inverted terrains" are a hallmark of Mars, its surface sculpted by hundreds of millions of years of dusty winds blowing over volcanic rock.

View Images PHOTOGRAPH BY BABAK TAFRESHI, TWAN

Our Milky Way galaxy gleams in all its splendor, as seen from a desert observatory in a recent picture released by the astronomy-education project The World At Night (TWAN).

The clear, dry desert air provides a perfect home for the La Silla Observatory, where the 11.8-foot (3.6-meter) New Technology Telescope (NTT) makes its nightly rounds of the sky's far reaches. The telescope rests between the open doors in the photo.