This is an artist’s conception of the sequence of events that will take place just prior to landing a life-detection laboratory on the surface of Mars on July 4, 1976. Above right, the Viking spacecraft, composed of an orbiter and a lander, has been in orbit around the Red Planet since June 19, 1976, taking pictures of the planned landing site to ascertain its safety before releasing the lander (top, left) for its threeto five-hour descent. Protected by aeroshells, the heat-sterilized lander hurtles into the thin Martian atmosphere at a speed of about 10,000 mph, to be slowed first by aerodynamic drag until the shell is discarded, then by parachute (center) and finally by retrorockets to assure a gentle landing. Instruments will study the structure and composition of the Martian atmosphere as the lander drifts down. Viking 2 is scheduled to arrive at Mars on Aug. 7 and touch down on the surface on Sept. 4.

The Pioneer 11 spacecraft launched from Cape Canaveral forty years ago, on April 5, 1973. Pioneer 11’s path through Saturn’s outer rings took it within 21,000 km of the planet, where it discovered two new moons (almost smacking into one of them in September 1979) and a new “F” ring. The spacecraft also discovered and charted the magnetosphere, magnetic field and mapped the general structure of Saturn’s interior. The spacecraft’s instruments measured the heat radiation from Saturn’s interior and found that its planet-sized moon, Titan, was too cold to support life.

This image from Pioneer 11 shows Saturn and its moon Titan. The irregularities in ring silhouette and shadow are due to technical anomalies in the preliminary data later corrected. At the time this image was taken, Pioneer was 2,846,000 km (1,768,422 miles) from Saturn.

This view shows the launch pad that Explorer 1 launched from in 1958.

American astronomer Clyde Tombaugh discovered Pluto, the ninth planet in our solar system, on February 18, 1930. Many key questions about Pluto, it’s moon Charon, and the outer fringes of our solar system await close-up observations.

A proposed NASA mission called New Horizons, depicted in the artist’s concept above, would use miniature cameras, radio science experiments, ultraviolet and infrared spectrometers and space plasma experiments to study Pluto and Charon, map their surface compositions and temperatures, and examine Pluto’s atmosphere in detail.

This artist’s concept of the proposed Mars Sample Return mission shows the entry, descent and landing sequence that the lander would undergo on its way to Mars.

A crucial step in the Mars Sample Return mission would be to launch the collected sample away from the surface of Mars. This artist’s concept depicts a Mars ascent vehicle starting a sample of Mars rocks on their trip to Earth.

On the 84th and 85th Martian days of the NASA Mars rover Curiosity’s mission on Mars (Oct. 31 and Nov. 1, 2012), NASA’s Curiosity rover used the Mars Hand Lens Imager (MAHLI) to capture dozens of high-resolution images to be combined into self-portrait images of the rover.

The mosaic shows the rover at “Rocknest,” the spot in Gale Crater where the mission’s first scoop sampling took place. Four scoop scars can be seen in the regolith in front of the rover. A fifth scoop was collected later.

Self-portraits like this one document the state of the rover and allow mission engineers to track changes over time, such as dust accumulation and wheel wear. Due to its location on the end of the robotic arm, only MAHLI (among the rover’s 17 cameras) is able to image some parts of the craft, including the port-side wheels.

The Helios-A solar probe launched on Dec. 10, 1974 from Cape Canaveral Air Force Station, Fla.

As it looped around the Sun in an orbit that took it from Earth’s orbit (1 AU from the Sun) to about 0.3 AU from the Sun and back again, Helios-A studied the solar wind, magnetic and electric fields, cosmic rays, and dust in interplanetary space. It flew within 47 million km of the Sun at a speed of 238,000 km per hour, the closest any human-made object had been. Its data indicated the presence of 15 times more micrometeorites close to the Sun than there are near Earth.

On Dec. 14, 1962, NASA’s Mariner 2 spacecraft sailed close to the shrouded planet Venus, marking the first time any spacecraft had ever successfully made a close-up study of another planet. It flew by Venus as planned at a range of 34,762 km (21,600 miles), scanning the planet’s atmosphere and surface for 42 minutes.

The spacecraft showed that surface temperature on Venus was at least 425°C (797°F) on both the day and night sides, hot enough to melt lead. It also showed that Venus rotates in the opposite direction from most planets in our solar system, has an atmosphere mostly of carbon dioxide with very high pressure at the planet’s surface, continuous cloud cover and no detectable magnetic field. It also found the solar wind streams continuously and that the density of cosmic dust between planets is much lower than it is near Earth.

Tethys may not be tiny by normal standards, but when it is captured alongside Saturn, it can’t help but seem pretty small.

Even Saturn’s rings appear to dwarf Tethys (660 miles, or 1,062 kilometers across), which is in the upper left of the image, although scientists believe the moon to be many times more massive than the entire ring system combined. This view looks toward the unilluminated side of the rings from about 18 degrees below the ringplane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Aug. 19, 2012.

The view was acquired at a distance of approximately 1.5 million miles (2.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 63 degrees. Image scale is 86 miles (138 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Marshall Space Flight Center is testing a new robotic lunar lander test bed that will aid in the development of a new generation of multi-use landers for robotic space exploration. The test article is equipped with thrusters that guide the lander, one set of which controls the vehicle’s attitude that directs the altitude and landing. On the test lander, an additional thruster offsets the effect of Earth’s gravity so that the other thrusters can operate as they would in a lunar environment.

The Cassini team sends “bats wishes” for a happy, healthy and fun Halloween.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C.

[Happy Halloween from sic itur ad astra as well - ed]

Marie Curie, the backup for the 1997 Mars Sojourner rover, sits next to a next-generation Mars Exploration Rover in this December 2002 photo. Sojourner went to Mars as part of the Pathfinder mission, which laid the groundwork for the more advanced Mars Exploration Rovers.

[Mother and daughter photo - ed]

An approximate natural-color image shows Saturn, its rings, and four of its icy satellites.

[Voyager’s encounter with Saturn did produce some amazing images and this is just one of the many that could have been chosen - ed]