For Scientists: Science Overview
The Mars 2020 mission supports the overall science strategy of NASA’s Mars Exploration Program: Seek signs of life.
The Mars 2020 mission additionally contributes to the Program’s four key science goals:
- Determine if Mars Ever Supported Life
- Understand the Processes and History of Climate on Mars
- Understand the Origin and Evolution of Mars as a Geologic System
- Prepare for Human Exploration
The Mars 2020 mission has four primary objectives:
- Explore an astrobiologically relevant ancient environment on Mars to decipher its geological processes and history, including the assessment of past habitability.
- Assess the biosignature preservation potential within the selected geological environment and search for potential biosignatures.
- Demonstrate significant technical progress towards the future return of scientifically selected, well-documented samples to Earth.
- Provide an opportunity for contributed HEOMD or Space Technology Program (STP) participation, compatible with the science payload and within the mission’s payload capacity.
To meet these objectives, the Mars 2020 Perseverance rover carries seven scientific instruments and a sample acquisition, processing, and caching system. The various payload elements work together to detect and study potential sampling targets with remote and in situ measurements; to observe the dust and atmospheric environment around the rover; and, to prepare for future human exploration by demonstrating in situ resource utilization technology (ISRU).
Landing and Exploration Site
The Perseverance rover is designed to investigate a site that shows clear evidence for ancient aqueous processes and an astrobiologically relevant ancient environment based on orbital data. The rover is capable of determining the habitability of an ancient environment, which requires an evaluation of the characteristics of the environment and the processes that influence it from microscopic to regional scales and a comparison of those characteristics with what is known about the capacity of life, as we know it, to exist in such environments. Some records of habitability may not be preserved or detectable; a key strategy for interpreting past habitability is to seek geochemical or geological proxies for past conditions, as recorded in the chemistry, mineralogy, texture, and morphology of rocks.
Mars 2020 is not designed to detect extant vital processes that would expose present-day microbial metabolism. Rather, it is designed to search for signs of potential ancient life: biosignatures. A biosignature is defined as an object, substance and/or pattern whose origin specifically requires a biological agent. Useful biosignatures must be preserved and be amenable to detection. Confidence in identifying a biosignature in a rock not only depends upon whether that signature could be identified by its inherent properties (e.g. chemical composition, mineralogy, structure or isotopic composition); it also depends upon understanding the geologic context in which the potential biosignature occurs. For example, it is important to know whether the rock unit hosting the potential biosignature likely formed in a habitable environment capable of supporting such biological entities and whether the subsequent processes affecting the rocks enabled the potential biosignature to be preserved to the present day. Perhaps the most important aspect of geologic context is whether the processes that occurred could have produced the observed biosignature-like feature abiotically.
Assessing the biosignature preservation potential within a formerly habitable environment and searching for potential biosignatures begins with the in situ measurements necessary to identify and to characterize promising outcrops. Confidence in interpreting the origin(s) of potential biosignatures increases with the number of them identified and with a better understanding of the attributes and context of each. However, thorough characterization and definitive discovery of martian biosignatures requires analyses of samples returned to Earth.
Therefore, the Perseverance rover is designed to assemble a cache of scientifically selected, well-documented samples packaged in such a way that they could be returned to Earth in an as-yet-unplanned future mission, following planetary protection protocols. The ability to collect and to cache scientifically compelling, well-documented samples from in situ rock outcrops is unprecedented in Mars exploration and is the necessary first step in a systematic plan to search for life.
Early demonstration of critical technologies, as well as the gathering of environmental data, is key to potential future human exploration missions to Mars. ISRU is an architecture enabling technology for human missions to Mars, which likely will depend on ISRU for producing the propellants needed for the return trip to Earth; ISRU can greatly reduce mass transported to the martian surface.
Previous surface missions all have been capable of measuring the composition of rocks (mineralogy and chemistry, and on MSL also organics and isotopes), but the emphasis has been on measurements that average the composition over an area of several cm2 or volume of several cm3 (APXS, Mossbauer, Mini-TES, CheMin, SAM). However, based on more than a century of careful geologic work on Earth, it is clear that observing compositional variations in relation to fine-scale textures and structures provides enormous interpretive power for understanding how rocks were formed and modified: this is the science of petrology. Such observations are especially valuable for interpreting unusual small-scale features and patterns in rocks, a study that is essential to the search for biosignatures. The Mars 2020 instrument suite shifts away from bulk measurements, instead making higher resolution, spatially coordinated measurements of rock composition, texture, and microstructure. These state-of-the-art measurements are the cornerstone of the in situ science strategy, and will pave the way to major advances in our understanding of Mars.