Polar Caps of Mars
Polar Caps of Mars
As soon as Herschel had invented the spectroscope, humans were thenceforth able to tear apart light photons of different energies, and we could use their variations to study and observe the caps of Mars. Using telescopes, the results were ambiguous.
Back on Earth, Bruce Murray and <ref> published a paper suggesting there was a CO2 cycle. Let's look at what they found. <insert eqn of co2 ice stability under Martian pressure, explain it slowly>
Mariner 9 instruments and findings
NASA's hugely successful Mariner 9 mission was launched in May 1971 and was the first spacecraft to enter Martian orbit in November 13, 1971. Mariner 9 carried two primary spectroscopic instruments with them, and were able to use these that the polar caps were not just water ice. <more findings to come>
Viking instruments and findings
Hugh Kieffer was the PI of the Thermal Emission instrument on the Viking mission, they were able to isolate CO2 by different temperature. <insert pic of CO2 finding>
Following the hugely successful Mariner and Viking missions, NASA sought to take a quantum leap in Mars exploration with their next mission. Called "Mars Observer", it was launched on September 1992, and just prior to inserting itself into orbit around Mars in August 1993, all contact with the spacecraft was lost, probably due to a fuel and oxidiser leak to the common propellant system. I can still remember being very sad about this, and seeing a display dedicated to the mission on my first visit to the US in 1994 at the Kennedy Space Flight Center.
Mars Global Surveyor
However, the instruments of Mars Observer were put on Mars Global Surveyor and the Mars Reconnaissance orbiter that arrived in 2006. He used the more accurate observations to map the seasonal co2 ice retreat <ref> and he also used it to discover the "cryptic region" in the south.Mars Global Surveyor carried a more accurate thermal instrument built by Phil Christensen and Hugh Kieffer was part of his team.
Polar Cap Obliquity
The most accurate eqns for Mars' location were given in a paper by Laskar et al. (1994). His eqns extend eqn 1 by several terms, here is an example <eqn 2>. These results were updated in 2004 by Laskar, and have recently (2019 LPSC abstract) have been re-analysed by Dr. Bruce Bills and James Keane at JPL.
We can get a simple equation to describe this idea of seasonal caps. <ref greve stuff>
Layering of the Polar Caps
Viking found layering.
In one of the most exciting findings of my times on Mars, a radar observation was made by SHARAD that located buried co2 ice beneath the south polar cap. The paper estimated <show plot and did they have an eqn> that the CO2 released from that deposit.
Seasonal Polar Caps
Mars Global Surveyor was able to map deposition of CO2 ice seasonally with the LIDAR. <insert figure>
Insert Mars Express findings of grain size variations
Insert CRISM seasonal polar maps