William Atkins
Wednesday, 28 May 2008 21:40
Science -
Space
Page 1 of 2
A possible cosmic ray impinging on the Mars Reconnaissance Orbiter may have prevented the Phoenix Mars Lander from receiving radio messages during its preliminary activities on the Red Planet.
The Phoenix Lander communicates with ground controllers on Earth through two other spacecraft, which are orbiting about Mars: the Mars Reconnaissance Orbiter and the 2001 Mars Odyssey.
The Reconnaissance Orbiter turned itself off earlier, and mission controllers think it did so to protect itself from a cosmic ray.
Commonly called “cosmic rays,” these very energetic particles consist primarily of helium nuclei (also called alpha particles), along with a small number of electrons (sometimes named beta minus particles).
They come from the Sun, other stars in the Milky Way galaxy, and other similar (and still other very different) objects contained within the Universe.
Mission controllers tried to tell the Phoenix Lander to move its 7.7-foot (2.3-meter) robotic arm using UHF (ultra-high frequency) radio signals. Using the Reconnaissance Orbiter to relay the information, the probe had earlier, on Tuesday, May 27, 2008, turned its radio off.
The robotic arm was held in a protective sleeve while Phoenix lifted off from Earth, traveled to Mars, and descended through the atmosphere of the planet on its way to its landing spot. The command was designed to lift the arm out of its sleeve so that it could be used to dig in the permafrost around its landing area.
Mission managers with the Reconnaissance Orbiter mission believe that it turned off its radio to protect itself from potential damage that a cosmic ray could have caused its communication system.
However, NASA managers now report that the radio onboard the Reconnaissance Orbiter has been turned back on. The new order to carry out the movement of the robotic arm has been now relayed to the Phoenix.
The temporary communications blackout caused a one-day delay in getting the Lander prepared to carry out its prime mission: to dig through the icy ground in the northern plains of Mars in order to investigate and analyze the composition of the surface and subsurface regions around the landing point of Phoenix.
So far, the camera aboard the Mars Reconnaissance Orbiter shows that Phoenix landed on an edge of a trough, which is considered an ideal location for digging.
Specifically, Phoenix landed in what is called “Green Valley,” within Vastitas Borealis. On the northern hemisphere of Mars, at this time, it is late spring. Such conditions allow the Sun to shine on the solar panels of Phoenix for the entire Martian day--providing plenty of power to the spacecraft.
By late June 2008, the northern hemisphere will be in its summer season, and the Sun will be at its maximum elevation in the sky. These conditions are perfect for Phoenix to easily carry out its mission.
By September, Phoenix will begin to lose the full effects of the Sun (as the star begins to set in the sky). At this time, the intended mission for Phoenix will be complete.
It is hoped that Phoenix will be able to continue with more data gathering at this time. However, as its solar panels receive less sunlight its power gathering ability will be reduced. Eventually, Phoenix will be unable to continue.
More information about the robotic arm and camera appears on the next page.
