NASA Ames Mars Climate Modeling Group

Mission Involvement

Members of the Mars Climate Modeling Group have been directly involved in many missions and have provided model results to assess the surface environment for landers, upper atmosphere variability for aerobraking, and the general characteristics of the Martian atmosphere for mission concept studies.
Viking Mission »

The first such effort dates back to the Viking mission when Pollack et al. (1976) used the model to predict winds and surface conditions for the Viking landers. Though they were not the major factor for site selection, the model simulations were considered by the Viking project when it was trying to find a safe place to set the landers down. (Landing in uneven terrains strewn with boulders was the major concern.) The model successfully predicted that surface winds would not be strong enough to threaten the safety of the landers during the parachute phase of the descent.

Viking Mission Orbiter

Separation of the Viking descent module from the Orbiter.

Pathfinder Mission »

Twenty years later, the Ames GCM performed a similar service for the Pathfinder mission. By then the model vertical domain was extended to high enough altitudes to include a prediction of the temperature and density profiles. Such a prediction, along with general meteorological conditions at the surface, was published just prior to the landing (Haberle et al. 1997), and an assessment of how well the model performed based on the actual Pathfinder observations was published after the landing (Haberle et al., 1999). Overall, the model was fairly successful in its predictions.

Pascal Mission Pathfinder Pascal Mission Mars Surface Photo

Pathfinder's entry and descent into the Martian atmosphere (left) and one of its views of the surface after landing (right).

Mars Global Surveyor and Mars Odyssey Mission »

When Mars Observer failed to achieve orbit in 1993, NASA decided to re-fly the same payload on two smaller spacecraft that would utilize aerobraking to achieve orbit. This was done in order to save on fuel and, hence, mass. The two spacecraft were the Mars Global Surveyor, launched in November of 1996, and Mars Odyssey, launched in April 2001. Upon arrival at Mars, these spacecraft were inserted into highly elliptical orbits that dipped into the upper atmosphere at periapsis to slow down and circularize their orbits. The depth to which the spacecraft dipped into the atmosphere was critical to the safety and overall success of the aerobraking process. The Ames model was used to help evaluate the optimal altitudes for aerobraking and provide an estimate of the variability in the density fields that could be encountered (e.g., Hollingsworth et al. 1997). Aerobraking has now become a standard for circularizing orbiters at Mars.

Mars Global Suveryor Aerobraking Graphic

(Click to enlarge) Aerobraking profile for Mars Global Suveryor.

Mesoscale Models »

Most of the atmospheric simulations for landers are now done with mesoscale models which have become very useful tools for studying small scale circulations and convection in the Martian atmosphere. The Ames model is often used in conjunction with these models to provide the large-scale boundary conditions for their high resolutions grids.

Thus far, the Ames model has been coupled to the MM5 mesoscale model being developed at Oregon State University (OSU) by Jeff Barnes and Dan Tyler, and the Mars Regional Atmospheric Modeling System (MRAMS) under development at Southwest Research Institute by Scot Rafkin and Tim Michaels. These coupled models have been used to support engineering design studies for the Mars Exploration Rovers (Rafkin and Michaels, 2003) and the Phoenix lander (Tyler et al., 2008). Both the OSU and MRAMS models are presently being used to assess meteorological conditions at the proposed Mars Science Laboratory landing sites.

Animation of afternoon convection on Mars.

(Click to play) Animation of afternoon convection on Mars.

Pascal Mission »

A particularly useful application of the Ames Mars GCM has been for mission concept studies. During the late 1990’s and early 2000’s, the Ames group was heavily involved in the scientific design of meteorological network missions. The mission concept that emerged from these efforts, known as “Pascal”, sought to deliver as many as 24 globally-distributed surface stations that would make regular hourly measurements of basic meteorological parameters for many Mars years. Though Pascal was considered technically too risky, the work produced a novel design for long-lived power sources, small compact EDL systems, and delivery methods for multiple probes on approach. But most importantly, the work refined the scientific rationale for network missions, the measurement requirements, and the operational strategy for simultaneous measurements from many widely dispersed probes (see Haberle and Catling, 1996, for details).

Pascal Mission Pathfinder

The Pascal Mars Meteorology Network Mission as proposed in 2002.

Hadley Mission »

More recently the Ames group proposed an orbiter mission, known as “Hadley”, to the Scout program. This orbiter precessed in local time and measured winds and various trace gases. The Ames model was used to help determine precession rates to capture tidal signatures, and measurement requirements to assess global energy balance. Though not selected, the basic features of that mission, sweeping through local time and measuring trace gases, are similar to that for the orbiter component of the joing NASA/ESA ExoMars/Trace Gas Orbiter mission scheduled for launch in 2016.

Pascal Mission Pathfinder

The orbiter component of the NASA/ESA ExoMars/Trace Gas Orbiter mission.

Reference

The Ames Mars General Circulation Model has been involved in interpreting data from many Mars missions since the dawn of the spacecraft era. Click here for a complete list of all spacecraft missions to Mars.

Mars Mission Links