[U14-01] 50 Years of Mars Exploration: Past and Ongoing NASA Missions Pave the Way for Determining Whether There Was Life on Mars
★Invited Papers
Keywords:Mars, NASA, Missions
NASA’s 50-plus years of Mars exploration has revealed a planet once more Earth-like and habitable than today. Nevertheless, the Mariner 4 flyby mission in 1965 and the subsequent Mariner 6 and 7 flybys in 1969 imaged mostly cratered surfaces. Mariner 9 entered orbit in 1971, studied the atmosphere and surface, and was the first mission to confirm the diversity of landforms that included volcanoes and channels.
The Viking missions provided the first truly global view of Mars starting in 1976 and included the landing of Viking 1 in Chryse Planitia and Viking 2 in Uptopia Planitia. The orbiters took ~50,000 images and both landers acquired/analyzed soil samples that provided important data on composition and the potential for life. The Viking 1 lander survived until 1982.
Formation of NASA’s Mars Exploration Program in 1993 led to focus on whether life ever arose on Mars, characterizing the planet’s climate and geology, and preparing for human exploration. The first program mission was the Mars Global Surveyor (MGS) orbiter arriving in 1997 and operating until 2006. MGS studied the atmosphere, surface, and interior, and science highlights include global maps of topography and mineralogy, images of gullies and fluvial deltas, and detection of magnetic surface anomalies. Mars Pathfinder and the Sojourner rover also arrived in 1997, demonstrated the feasibility of airbag landing and the value of surface mobility, and characterized rock sizes and textures consistent with water-lain flood deposits. Mars Odyssey arrived in orbit in 2001 and further mapped surface composition, discovered widespread deposits of mid and high latitude ice, and characterized the near-space radiation environment.
The Mars Exploration Rovers (MER) Spirit and Opportunity landed on Mars using airbags in early 2004, with Spirit operating until 2010 and Opportunity end of mission occurring in 2019. MER focused on understanding the geology and role of water in shaping the surface around the landing sites: Spirit was targeted to Gusev Crater, site of a possible former lake in a large impact crater, and Opportunity landed at Meridiani Planum, where orbital detection of hematite at the surface by Odyssey suggested past water activity. Both rovers found evidence of past environments where water was once active at and below the surface and that may have been habitable.
The Mars Reconnaissance Orbiter (MRO) arrived in 2006, enabling a new phase of global, detailed mapping of surface composition, surface morphology, and the atmosphere. MRO is ongoing and results range from mapping clay-rich deposits around Mawrth Vallis to identifying probable polar geysers to characterizing small, recurring slope lineae. The high spatial and spectral resolution of MRO data sets opened a new era of landing site studies crucial to the assessment and certification of the landing site in Gale crater for the Mars Science Laboratory (MSL) Curiosity rover.
MSL landed in 2012 using a “sky crane” system with goals that included understanding past Martian climate and geology and determining whether the landing site ever harbored habitable conditions. Major discoveries include discovery of complex organic molecules and characterization of deposits whose chemistry and extent confirm the presence of a relatively long-lived lake and associated habitable conditions more than 3 Ga.
Other missions augment our understanding of the evolution of Mars: Phoenix landed in 2008 and explored high northern latitudes; Maven arrived in orbit in 2014 and continues to explore the upper atmosphere to understand climate evolution; and InSight landed in 2018 and is studying the deep interior of Mars. Odyssey, MRO, and Maven also provide data relay from MSL and InSight critical to increasing their science return. Collectively, these missions comprise an organized approach to Mars exploration that pave the way for future missions to cache and return samples and determine whether there was ever life on Mars.
The Viking missions provided the first truly global view of Mars starting in 1976 and included the landing of Viking 1 in Chryse Planitia and Viking 2 in Uptopia Planitia. The orbiters took ~50,000 images and both landers acquired/analyzed soil samples that provided important data on composition and the potential for life. The Viking 1 lander survived until 1982.
Formation of NASA’s Mars Exploration Program in 1993 led to focus on whether life ever arose on Mars, characterizing the planet’s climate and geology, and preparing for human exploration. The first program mission was the Mars Global Surveyor (MGS) orbiter arriving in 1997 and operating until 2006. MGS studied the atmosphere, surface, and interior, and science highlights include global maps of topography and mineralogy, images of gullies and fluvial deltas, and detection of magnetic surface anomalies. Mars Pathfinder and the Sojourner rover also arrived in 1997, demonstrated the feasibility of airbag landing and the value of surface mobility, and characterized rock sizes and textures consistent with water-lain flood deposits. Mars Odyssey arrived in orbit in 2001 and further mapped surface composition, discovered widespread deposits of mid and high latitude ice, and characterized the near-space radiation environment.
The Mars Exploration Rovers (MER) Spirit and Opportunity landed on Mars using airbags in early 2004, with Spirit operating until 2010 and Opportunity end of mission occurring in 2019. MER focused on understanding the geology and role of water in shaping the surface around the landing sites: Spirit was targeted to Gusev Crater, site of a possible former lake in a large impact crater, and Opportunity landed at Meridiani Planum, where orbital detection of hematite at the surface by Odyssey suggested past water activity. Both rovers found evidence of past environments where water was once active at and below the surface and that may have been habitable.
The Mars Reconnaissance Orbiter (MRO) arrived in 2006, enabling a new phase of global, detailed mapping of surface composition, surface morphology, and the atmosphere. MRO is ongoing and results range from mapping clay-rich deposits around Mawrth Vallis to identifying probable polar geysers to characterizing small, recurring slope lineae. The high spatial and spectral resolution of MRO data sets opened a new era of landing site studies crucial to the assessment and certification of the landing site in Gale crater for the Mars Science Laboratory (MSL) Curiosity rover.
MSL landed in 2012 using a “sky crane” system with goals that included understanding past Martian climate and geology and determining whether the landing site ever harbored habitable conditions. Major discoveries include discovery of complex organic molecules and characterization of deposits whose chemistry and extent confirm the presence of a relatively long-lived lake and associated habitable conditions more than 3 Ga.
Other missions augment our understanding of the evolution of Mars: Phoenix landed in 2008 and explored high northern latitudes; Maven arrived in orbit in 2014 and continues to explore the upper atmosphere to understand climate evolution; and InSight landed in 2018 and is studying the deep interior of Mars. Odyssey, MRO, and Maven also provide data relay from MSL and InSight critical to increasing their science return. Collectively, these missions comprise an organized approach to Mars exploration that pave the way for future missions to cache and return samples and determine whether there was ever life on Mars.