Mars Orbiters ‘Duck and Cover’ for Comet Siding Spring Encounter

NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data, as Comet C/2013 A1 Siding Spring heads toward a close flyby of Mars on Oct. 19.

The comet’s nucleus will miss Mars by about 82,000 miles (132,000 kilometers), shedding material hurtling at about 35 miles (56 kilometers) per second, relative to Mars and Mars-orbiting spacecraft. At that velocity, even the smallest particle — estimated to be about one-fiftieth of an inch (half a millimeter) across — could cause significant damage to a spacecraft.

NASA currently operates two Mars orbiters, with a third on its way and expected to arrive in Martian orbit just a month before the comet flyby. Teams operating the orbiters plan to have all spacecraft positioned on the opposite side of the Red Planet when the comet is most likely to pass by.

The European Space Agency is taking similar precautions to protect its Mars Express (MEX) orbiter.
  • For more information about the Mars flyby of comet Siding Spring, click here.
Credit: NASA/JPL-Caltech

That’s today. Here’s hoping none of our robotic emissaries take any damage!




The First Lady Astronaut Trainees / Mercury 13

"The men go off and fight the wars and fly the airplanes and come back and help design and build and test them. The fact that women are not in this field is a fact of our social order."

- John Glenn of the Mercury 7, testifying before a House subcommittee in 1962

"The women underwent the identical tests that the male candidates had undergone. In the end, 68% of the women passed with ‘no medical reservations’ compared to 56% of the men. The 13 females who passed were known as the Mercury 13. They were Bernice ‘Bea’ Steadman, Janey Hart, Geraldine ‘Jerri’ Sloan Truhill, Rhea Allison Woltman, Sarah Lee Gorelick Ratley, Jan Dietrich, Marion Dietrich, Myrtle Cagle, Irene Leverton, Gene Nora Jessen, Jean Hixson, Wally Funk and Geraldyn ‘Jerrie’ Cobb…

Cobb had tested in the top 2% of all tested candidates, male and female.”

The Lovelace Woman in Space Program (1960-1962)

Amazing, I had never heard of this!



Solar wind and Mars’ Atmosphere

Mars does not have a single unified magnetic field like Earth. It has smaller, more fractured fields which cover the planet and have different intensities and polarities. The absence of magnetic protection allows the supersonic solar wind flow to directly interact with the Martian ionosphere.

The Sun constantly emits high-energy photons (gamma rays) and when one of these photons enters the atmosphere of Mars, it can crash into a molecule, knocking loose an electron and turning it into an ion. These ions can then crash into other molecules and fling atoms everywhere. Some of these atoms can be knocked, or sputtered, into space, causing atmospheric loss. The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. When the velocity of the solar wind increases, the Martian ionosphere is compressed and the ionopause (a boundary layer between the ionosphere and the solar wind) is displaced to lower altitudes.

Further Reading:

Credit: Chris Smith (HTSI), NASA/Nagoya University



Total Lunar Eclipse

A total lunar eclipse will take place on October 8, 2014. It is the latter of two total lunar eclipses in 2014, and the second in a tetrad (four total lunar eclipses in series).

Lunar eclipses occur when the Moon passes through the Earth’s shadow, however, for a total lunar eclipse to occur, the Moon and Earth have to be on the same orbital plane with the Sun — this is known as a syzygy. During a total lunar eclipse, the Moon travels completely into the Earth’s shadow (umbra). Even though the Moon is immersed in the Earth’s shadow, indirect sunlight will still reach the Moon. As sunlight passes through Earth’s atmosphere it gets absorbed and then radiated out (scattered). The atmosphere filters out most of the blue-colored light. What’s left over is the orange- and red-colored light. From the Moon’s perspective the Earth’s edge appears to glow bright orange or red. This red-colored light passes through our atmosphere without getting scattered, projecting indirect, reddish light onto the Moon.

For more information:

Credit: NASA/SVS