Inside Opportunity: In the land of plenty
Winter is Coming! Opportunity is on the floor of Marathon Valley, located on the western rim of Endeavour Crater on the surface of Mars. She is continuing a valley floor survey for clay minerals (phyllosilicates). Marathon Valley is some 1,050 feet (320 meters) long and up to 328 feet (100 meters) wide – and it is just the latest location that Opportunity has visited since the robot landed in January 2005.
We chose the name Marathon because upon initially reaching this valley we had covered the distance of an average Marathon race (26.2 miles). Not bad for a rover originally slated to drive just around 2,000 feet (600 meters).
Our venerable Mars Exploration Rover Opportunity continues to function in good health 11 years and 9 months into its mission. One that had only been planned to last a mere 90 days. In fact, as of this writing, Opportunity has been working and exploring the Red Planet for 4,178 sols now! A sol is what we call a day on Mars; it is 24 hours, 39 minutes long. A sol is 2.7 percent longer than a day on Earth.
As our exploration of Marathon Valley continues, we are presently concentrating on the eastern and southern areas of the valley and moving away from the northern wall. This is because we need to have Opportunity tilted more to the north in order to get better Sun exposure for our solar panels.
This will change as power requirements drive the need to take the rover even further south toward the southern wall of Marathon Valley. Here we will also have slopes greater than or equal to 10° which will improve the power situation.
Seasons on Mars last about twice as long as their Earthly counterparts. This is due to the fact that one year on Mars (687 Earth days) lasts almost two Earth years. We are currently deep into the Autumn season (in the Southern hemisphere) and preparing for the coming Winter (winter solstice is January 3, 2016).
For our solar-powered rover, this means that our power is down considerably from ∼750 Watt-hours in the spring and summer months to 325 Watt-hours and dropping as we dip into winter. However, we are still able to drive and do good science!
It is more challenging but for us on the science and engineering teams well, we have been here before. In fact, this will be our 7th winter on Mars. Spring will begin on July 4, 2016, and summer on November 28, 2016.
We are driving Opportunity in a mode that uses what we call ‘lily pads’. Lily pads are regions that are tilted more toward the north. These regions allow more direct sunlight to reach our solar panels and give us maximum power. This is the mode we will be in for the duration of Winter for survival. This mode will restrict what areas of Marathon Valley we can and cannot explore. Not to worry, because the areas that will be off-limits due to power constraints in the winter will be accessed next spring and summer when power is abundant. At present, Opportunity’s odometer stands at 42,620.49 meters (26.48 miles).
The one thing that Opportunity has demonstrated is that the longer year, longer seasons, and an array of areas to explore – make Mars a land of plenty.
- Dr. James Rice, Jr. – Opportunity Rover Geology Team Leader – Oct. 21, 2015
Dr. Jim W. Rice, Jr., is an Astrogeologist at the Planetary Science Institute, he has over 25 years research experience specializing on the surface geology and history of water on Mars. Dr. Rice is currently a Co-Investigator and Geology Team Leader on the Mars Exploration Rover Project (Spirit and Opportunity). Rice also has extensive mission experience as Associate Project Scientist on the Lunar Reconnaissance Orbiter and Mars Odyssey Orbiter Projects. He has been involved in Mars landing site selection and certification activities for every NASA Mars Mission since Mars Pathfinder. His career includes working for NASA, Astrogeology Headquarters of the United States Geological Survey, the Mars Spaceflight Facility located at Arizona State University and the Lunar and Planetary Laboratory located at the University of Arizona.