Icebreaker Life is a Mars lander mission concept proposed to NASA's Discovery Program. The mission involves a stationary lander that would be a near copy of the successful 2008 Phoenix and 2018 InSight spacecraft, but would carry an astrobiology scientific payload, including a drill to sample ice-cemented ground in the northern plains to conduct a search for biosignatures of current or past life on Mars. The science goals for Icebreaker Life focus on sampling ice-cemented ground for its potential to preserve and protect biomolecules or biosignatures. Icebreaker Life was not selected during the 2015 or 2019 Discovery Program competitions.
Mission profile The Icebreaker Life mission has been designed based on the successful 2008 Phoenix lander in terms of platform and northern landing site. The Icebreaker Life will also be solar-powered and will be able to accommodate the drill and the rest of the payload with only minor modifications to the original lander. Had it been selected for the Discovery program mission 13, the lander would have been launched no later than December 2021. The lander would arrive over the northern plains of Mars in 2022. Operations on the surface would last for 90 sols. Command, control, and data relay are all patterned after the Phoenix mission with relay to Mars orbiters and direct to Earth as a backup. Christopher McKay is the Principal Investigator. In 2010, the Icebreaker science payload was proposed as the baseline science payload for developing a joint NASA-SpaceX now-canceled mission that was called Red Dragon.
Objectives The Mars Icebreaker Life mission focuses on the following science goals:
Search for specific biomolecules that would be conclusive evidence of life. Perform a general search for organic molecules in the ground ice. Determine the processes of ground ice formation and the role of liquid water. Understand the mechanical properties of the Martian polar ice-cemented soil. Assess the recent habitability (5 million years ago) of the environment with respect to required elements to support life, energy sources, and possible toxic elements. Compare the elemental composition of the northern plains with mid-latitude sites. To further the current understanding of the habitability of the ice in the northern plains and to conduct a direct search for organics, the Mars Icebreaker Life mission focuses on the following science goals:
Search for specific biomolecules that would be conclusive evidence of past life. Biomolecules may be present because the Phoenix landing site is likely to have been habitable in recent Martian history. Ground ice may protect organic molecules on Mars from destruction by oxidants and radiation, and as a result organics from biological or meteorite sources may be detectable in polar ice-rich ground at significant concentrations. Perform a general search for organic molecules in the ground ice. If habitable conditions were present, then any organics may be of recent (<10 million years) biological origin. Determine the nature of the ground ice formation and the role of liquid water. There may have been liquid water generated in the surface soils in the north polar regions within the past <10 million years due to orbital changes in insolation. Understand the mechanical properties of the martian polar ice-cemented soil. Polar ice may be a resource for human exploration, and the mechanical properties will reflect the stratigraphy of ice and soil, which may inform models of climate history. Assess the recent habitability of the environment with respect to required elements to support life, energy sources, and possible toxic elements. The perchlorate present at the Phoenix site could provide a usable energy source if ferrous iron is present. A source of fixed nitrogen, such as nitrate, is required for habitability. Compare the elemental composition of the northern plains with mid-latitude sites. Duplicate samples could be cached as a target for possible return by a Mars sample return mission. If the samples were shown to contain organic biosignatures, interest in returning them to Earth would be high.
Science The results from previous missions, and the Phoenix mission in particular, indicate that the ice-cemented ground in the north polar plains is likely to be the most recently habitable place that is currently known on Mars. The near-surface ice likely provided adequate water activity (aw) during periods of high obliquity 5 million years ago, when Mars had an orbital tilt of 45°, compared to the present value of 25° and ground ice may have melted enough to preserve organic molecules, including organic biosignatures. The two Viking landers conducted in 1976 the first, and so far only, search for current life on Mars. The biology experiments sought to detect living organisms based on the hypothesis that microbial life would be widely present in the soils, as it is on Earth, and that it would respond to nutrients added with liquid water. The Viking biology experiments operated successfully on both landers, with an instrument showing signs of active bacterial metabolism, but it did not occur with a duplicate heat-treated sample. Other instruments yielded negative results with respect to the presence of organic compounds. The results of the Viking mission concerning life are considered by the general expert community, at best, as inconclusive. Scientists deducted that the ambiguous results may have been caused by an oxidant in the soil. The organic analysis instrument on Phoenix (TEGA) was also defeated by the presence an oxidant in the soil, but this lander was able to identify it: perchlorate. The SAM instrument (Sample Analysis at Mars) currently in use on board the Mars Science Laboratory's Curiosity rover, has three capabilities that should allow it to detect organics despite interference from perchlorate. A null result would establish that Earth-like life is likely not present in the ground ice, arguably the most habitable environment currently known on Mars, implying that Earth-like life is absent on Mars generally. This would lower the risk for biohazards during human exploration or sample return. However, this would not rule out life that does not have Earth-like biomarkers.
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