Question

Each of the following gives a statement that a future explorer might someday make. In each case, decide whether the claim seems plausible in light of current knowledge. Explain clearly; because not all of these have definitive answers, your explanation is more important than your chosen answer. The drilled sample from Mars brought up rock that contained microscopic droplets of liquid water.

Short answer

It's plausible if the droplets were trapped in favorable subsurface conditions.

Step-by-step solution

Understanding the Claim

The claim states that a drilled sample from Mars contained microscopic droplets of liquid water. Mars is known to have ice and some subsurface water deposits. Determining if these conditions allow for liquid water is critical.

Review Current Knowledge about Mars

NASA's explorations, including rovers like Curiosity and Perseverance, have found evidence of water in the form of ice, and conditions that may allow for liquid water transiently under certain conditions in the subsurface.

Consider Atmospheric and Temperature Constraints

Mars has a very thin atmosphere, leading to low pressure and temperatures, usually not conducive to stable liquid water on the surface. However, underground conditions might differ, permitting briny water to remain liquid briefly.

Evaluate Plausibility

Given that liquid water is rare due to the atmospheric conditions but potentially present in subsurface reservoirs, finding microdroplets in a drilled core sample could be plausible if these are transient or trapped.

Conclusion

While finding liquid water droplets in a Mars rock sample isn't highly likely, it's plausible if conditions trapped them in the rock before drilling. Thus, the claim seems possible under certain specific conditions.

Key concepts

Liquid Water on Mars

Liquid water on Mars has been a subject of much investigation and curiosity. While surface conditions on Mars typically don't support liquid water due to severe cold and low atmospheric pressure, science suggests that liquid water may still be possible under specific circumstances. Underneath the planet's surface, where temperatures are slightly higher and pressure conditions vary, there's potential for water to exist in liquid form.

Water on Mars might exist transiently or could be affixed within mineral deposits, which contain pockets of it in a hydrated state. The presence of salts in these pockets can lower the freezing point of water, making briny water a realistic possibility. The idea of liquid water on Mars remains an exciting prospect because of its implications for past or present life on the planet, and for future human exploration needs.

Martian Atmosphere

The Martian atmosphere is notably different from Earth's, profoundly influencing the presence of liquid water. Mars has a very thin atmosphere composed primarily of carbon dioxide, with just about 1% of Earth's atmospheric pressure at the surface. These conditions make sustaining liquid water on the surface extremely difficult as water would either freeze into ice, sublimating directly to gas, or evaporate rapidly.

However, atmospheric pressure and temperature have likely varied over time. During certain geological periods, Mars could have had a denser atmosphere, potentially allowing large bodies of liquid water to exist on its surface. Presently, the possibility of liquid water remains mostly under Mars's surface, where the conditions can differ significantly compared to those on the surface.

Subsurface Water Deposits

Subsurface water deposits are key to the ongoing search for life and understanding of water on Mars. These deposits are believed to exist in the form of ice or potentially liquid water, trapped deep beneath the surface. Mars' subsurface layers may keep water in a semi-liquid state due to geothermal heat and the insulating properties of the Martian soil and rock.

The concept of subsurface water reservoirs is supported by scientific evidence, such as radar data suggesting the presence of liquid lakes beneath polar ice caps. These findings raise interesting possibilities for life, as subsurface environments might provide more stable and protective conditions than those on the hostile Martian surface.

• Geothermal heat helps maintain liquid state.
• Salts contribute to lower freezing points.
• Protective geology can aid in water retention.

Curiosity Rover Findings

The Curiosity rover has been instrumental in changing our understanding of Mars. Launched by NASA in 2011, Curiosity has provided valuable data through its exploration of the Gale Crater, shedding light on the planet's geology and hinting at its watery past.

The rover has detected mineral compounds, such as clays and sulfates, which form in the presence of water. These minerals suggest that Mars once had environments where water was stable for extended periods, perhaps supporting microbial life. Curiosity's observations of methane emissions further intrigue scientists, as methane can be a by-product of both geological processes and biological activity.

Curiosity's findings assist in putting together Mars's climatic history, helping scientists identify ancient habitable environments and directing future missions to potential sites of interest for finding traces of life.