''Icebreaker Life'' is a
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
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
Insight is the understanding of a specific causality, cause and effect within a particular context. The term insight can have several related meanings:
*a piece of information
*the act or result of understanding the inner nature of things or of se ...
spacecraft, but would carry an
astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...
scientific payload, including a drill to sample ice-cemented ground in the northern plains to conduct a search for
biosignature
A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life on a planet. Measurable ...
s of current or past
life on Mars
The possibility of life on Mars is a subject of interest in astrobiology due to the planet's proximity and similarities to Earth. To date, no conclusive evidence of past or present life has been found on Mars. Cumulative evidence suggests that ...
.
The science goals for ''Icebreaker Life'' focus on sampling ice-cemented ground for its potential to preserve and protect
biomolecules
A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. Biomolecules include large macromolecules such as proteins, carbohydrates, lipi ...
or
biosignature
A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life on a planet. Measurable ...
s.
''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
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...
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
Christopher P. McKay (born 1954) is an American planetary science, planetary scientist at NASA Ames Research Center, studying atmosphere, planetary atmospheres, astrobiology, and terraforming. McKay majored in physics at Florida Atlantic Univers ...
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
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms ( ...
.
# 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
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms ( ...
. 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
Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
Solar irradiance is measured in watts per square metre ...
.
# 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
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
, 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
A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life on a planet. Measurable ...
, 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
In food science, water activity (''aw'') of a food is the ratio of its vapor pressure to the vapor pressure of water at the same temperature, both taken at equilibrium. Pure water has a water activity of one. Put another way, ''aw'' is the equi ...
(a
w) 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
biosignature
A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life on a planet. Measurable ...
s.
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
Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...
, 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
A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cat ...
. The SAM instrument (Sample Analysis at Mars
Sample Analysis at Mars (SAM) is a suite of instruments on the Mars Science Laboratory Curiosity (rover), ''Curiosity'' rover. The SAM instrument suite analyzed Organic compound, organics and gases from both atmospheric and solid samples.
It was ...
) 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.
Preservation of biomolecules
One of the key goals of the ''Icebreaker Life'' mission is to test the hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess o ...
that the ice-rich ground in the polar regions has significant concentrations of organics due to protection by the ice from oxidants and radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:
* ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...
. Non-biological organics from infalling meteorites could be detectable in polar ice-rich ground at significant concentrations, so they could be used as indicators that ice actually protect and preserve organic molecules, whether biological or not.
If non-biological organics are found, then the north polar regions would be compelling targets for future astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...
missions, especially because of the potential recent habitability (5 million years ago) of this ice. Target biomolecule
A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. Biomolecules include large macromolecules such as proteins, carbohydrates, lipids ...
s will be aminoacids, protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s, polysaccharide
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...
s, nucleic acids
Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic a ...
(''e.g''., DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
, RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
) and some of their derivatives, NAD+ involved in redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is t ...
reactions, cAMP for intracellular signals, and polymeric compounds such as humic acid
Humic substances (HS) are colored relatively recalcitrant organic compounds naturally formed during long-term decomposition and transformation of biomass residues. The color of humic substances varies from bright yellow to light or dark brown lead ...
s and polyglutamic acid
Polyglutamic acid (PGA) is a polymer of the amino acid glutamic acid (GA). Depending on where the individual monomers connect, PGA can be gamma PGA (poly-γ-glutamic acid, γ-PGA), the form where the peptide bonds are between the amino group of G ...
—formed by bacterial fermentation
Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...
.
;Ionizing radiation
Ionizing radiation
Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...
and photochemical oxidants are more damaging in dry regolith, therefore, it may be necessary to reach ~ deep where organic molecules may be shielded by the ice from the surface conditions. The optimal deposition rate for the landing site would be such that of drill will sample through 6 million years of sediment.
;Perchlorate
Perchlorate
A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cat ...
is the most oxidized form of the element chlorine
Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
, but it is not reactive at ambient conditions on Mars. However, if heated to above 350 °C perchlorate decomposes and releases reactive chlorine and oxygen. Thus, the ''Viking'' and ''Phoenix'' thermal processing of the soils would have destroyed the very organics they were attempting to detect; thus the lack of detection of organics by ''Viking'', and the detection of chlorinated organic species, may reflect the presence of perchlorates rather than the absence of organics.
Of particular relevance, some microorganisms on Earth grow by the anaerobic reductive dissimilation of perchlorate and one of the specific enzymes used, perchlorate reductase, is present in all known examples of these microorganisms. Also, perchlorates are toxic to humans, so understanding the chemistry and distribution of perchlorate on Mars might become an important prerequisite before the first human mission to Mars
The idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies since the late 1940s as part of the broader exploration of Mars. Long-term proposals have included sending settlers and terraforming the p ...
.
Habitability
While sunlight
Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...
is a powerful energy source for life, it is unlikely to be biologically useful on present Mars because it requires life to be at the surface exposed to the extremely lethal radiation and to dry conditions.
The team estimates that if ice-cemented ground at the landing site was in fact raised 5 million years ago to temperatures warmer than −20 °C, then the resultant water activity
In food science, water activity (''aw'') of a food is the ratio of its vapor pressure to the vapor pressure of water at the same temperature, both taken at equilibrium. Pure water has a water activity of one. Put another way, ''aw'' is the equi ...
(aw=0.82) may have allowed for microbial activity in the thin films of unfrozen water that form on the protected boundary beneath the soil and ice for temperatures above −20 °C. ''Icebreaker Life'' would study the concentration and distribution of ferrous iron, nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
, and perchlorate
A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cat ...
as a biologically useful redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is t ...
couple -or energy source- in the ground ice. McKay argues that subsurface chemoautotrophy is a valid energy alternative for Martian life. He suggests that perchlorate and nitrate could form the oxidizing partner in a redox couple if suitable reduced material were available.
;Nitrogen fixation
After carbon, nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
is arguably the most important element needed for life. Thus, measurements of nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
over the range of 0.1% to 5% are required to address the question of its occurrence and distribution. There is nitrogen (as N2) in the atmosphere at low levels, but this is not adequate to support nitrogen fixation
Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...
for biological incorporation. Nitrogen in the form of nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
, if present, could be a resource for human exploration both as a nutrient for plant growth and for use in chemical processes.
On Earth, nitrates correlate with perchlorates in desert environments, and this may also be true on Mars. Nitrate is expected to be stable on Mars and to have formed in shock and electrical processes. Currently there is no data on its availability.
Proposed payload
''Icebreaker Life'' would carry a rotary-percussive drill and the proposed scientific instruments have already been tested in relevant analogue environments and on Mars.
* Signs Of LIfe Detector (SOLID) instrument can detect whole cells, specific complex organic molecules, and polymers via fluorescence immunoassay
An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...
s. Using a single Life-Detection Chip (LDCHIP) measuring a few square centimeters, SOLID's antibody library can detect up to 300 different organic molecules. The instrument would carry 16 Life-Detection Chips.
*The Wet Chemistry Laboratory (WCL) is a powerful analytical instrument that would measure the pH, Eh, conductivity, and dissolved ions present in the ice-cemented ground. The WCL was used successfully on the 2007 ''Phoenix'' lander mission.
*A laser desorption mass spectrometer (LDMS) would detect and characterize a wide range of nonvolatile organic compounds. The LDMS uses a pulsed laser desorption/ionization (LDI) process, in which molecular ions are sampled directly from particulate samples at Mars ambient pressure, with no vacuum loading required. The LDMS method is not impacted by the presence of perchlorate.
*Rotary-percussive drill and a selected set of instruments. The drill penetrates in ice-cemented ground and the cuttings from this drill are sampled by a robotic sample handling system,
*The lander uses the ''Phoenix'' Surface Stereo Imager (SSI) for monitoring drill and sample delivery operations. It would provide important context information to estimate ice depth and also to understand any surface conditions that may affect mission operations and drill placement.
Planetary protection
The mission must comply with the planetary protection
Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth in the case of sample-return missions. Planetary protection refle ...
requirements established by NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
and the international Committee on Space Research (COSPAR).
See also
*Astrobiology
Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...
* Biological Oxidant and Life Detection
*ExoMars
ExoMars (Exobiology on Mars) is an astrobiology programme of the European Space Agency (ESA).
The goals of ExoMars are to search for signs of past life on Mars, investigate how the Martian water and geochemical environment varies, investigate ...
*Exploration of Mars
The planet Mars has been explored remotely by spacecraft. Uncrewed spacecraft, Probes sent from Earth, beginning in the late 20th century, have yielded a large increase in knowledge about the Martian system, focused primarily on understanding G ...
*Mars 2020
Mars 2020 is a NASA mission that includes the rover ''Perseverance (rover), Perseverance'', the now-retired small robotic helicopter ''Ingenuity (helicopter), Ingenuity'', and associated delivery systems, as part of the Mars Exploration Progra ...
*Water on Mars
Although very small amounts of liquid water may occur transiently on the surface of Mars, limited to traces of dissolved moisture from the atmosphere and thin films, large quantities of ice are present on and under the surface. Small amounts of ...
References
{{DEFAULTSORT:Icebreaker Life
Missions to Mars
Proposed NASA space probes
Discovery program proposals
Proposed astrobiology space missions