Late Martian Weather!
Images of the Martian Atmosphere
Lessons & Activities
Daily Martian Weather Report
The US space program reset its sights on Mars when the
Mars Global Surveyor (MGS)
spacecraft was launched from the Cape Canaveral (Florida) Air Station
on November 7, 1996. The purpose of the MGS mission is to study the
atmosphere, topography, geology, mineralogy, gravity and magnetic field
of the red planet for a full martian year (687 days). In addition, the
MGS mission will help future mission planners select landing sites for
robotic and, ultimately, manned expeditions to the martian surface. As
one of their primary goals, these future missions will seek to discover
whether life has ever existed on Mars. The MGS mission is managed for
NASA by the Jet Propulsion Laboratory in Pasadena, California.
The MGS Radio Science Team (RST) is utilizing ultrastable radio transmissions from the orbiting MGS spacecraft to probe the martian atmosphere and uncover the keys to the internal structure of that atmosphere and to the martian climate. The MGS RST is also using high-precision radio tracking of the MGS spacecraft to develop a detailed map of the gravity field of the red planet. Members of the MGS RST have developed an education outreach program which allows participating students and teachers to access and analyze martian atmospheric data as it is acquired by the RST. The participants also have the opportunity to compare the martian data with similar measurements which they make here on Earth. The outreach program has been targeted toward students in the 7th/8th grades and up, but students of all ages are welcome to participate in the program.
The mapping phase of the MGS mission began in early April, 1999. The mapping orbit is nearly circular about the poles of Mars, with a period of approximately two hours and an altitude of about 250 miles. The RST will acquire the bulk of their martian meteorological data during this phase of the mission.
The MGS Radio Science Team employs a technique called radio occultation to probe the martian atmosphere. Twice per orbit, MGS is occulted by Mars (once on entry and once on exit) and an ultrastable radio transmission from the spacecraft to Earth passes through and is perturbed (refracted) by the thin atmosphere of Mars. The radio transmissions are received by NASA Deep Space Network antennas here on Earth, and analyzed at Stanford University with special computer software. In the past, RST members have acquired radio occultation data from the atmospheres of most of the planets in the solar system and a number of their satellites.
Analysis of the perturbations to the phase of the radio transmission by the martian atmosphere yields profiles of the temperature and pressure of that atmosphere as a function of height above the martian surface. Team members are hopeful that sophisticated inversion techniques which they are developing will permit the derivation of temperature and pressure profiles with a vertical resolution of 10 meters! Except for periods when the MGS orbit geometry is not favorable, the radio occultation measurements of the martian atmosphere will be made throughout the remainder of the MGS mission. This data will yield a wealth of new information about the structure and dynamics of the martian atmosphere and the martian climate. A significant fraction of the MGS occultations will occur in the vicinity of the martian poles, but occultations will occur at nearly all latitudes during the mission.
The MGS RST education outreach program was developed with a consultant who has decades of experience teaching science at the middle and high school levels. Participants have access to temperature and pressure data from the martian atmosphere which have been acquired during occultations of the MGS spacecraft by Mars. Students may retrieve the data and track it over the course of the martian seasons. Students may also make daily measurements of their local weather (temperature, pressure and relative humidity) and track that information as well. By comparing the data from the two planets and investigating the similarities and differences, participants may gain a good understanding of atmospheres, weather and climate. Participants also have the opportunity to experience the excitement and inner workings of planetary exploration and the US space program.
Interactions between outreach program participants and the MGS RST take place through a World Wide Web site developed specifically for the outreach program. The site includes forms for students to download the martian atmospheric data and to upload their own local weather measurements. Tools are available to view graphs of the meteorological data from both Earth and Mars, and the experimental conditions under which the data were acquired. The Web site also includes a Teacher's Guide and a series of introductory lessons and activities to give participants a background in atmospheres, weather and climate. Completion of the lessons and exercises will ensure that students have the knowledge that they require to understand and interpret the MGS RST data from the martian atmosphere and their own measurements of Earth's atmosphere.
As mentioned above, the mapping phase of the MGS mission began in April, 1999. New results from the martian atmosphere will continue to be made available to program participants as they become available. Interested teachers may begin this program with their students at any time. RST members are excited about this education outreach program and about the opportunity to share their data and their wisdom with young students. For additional information, please contact Joe Twicken at the e-mail address or phone number above.