NASA is fully intent on exploring ocean worlds. However, it is a complicated mission for which rover vehicles such as those sent to the Moon or Mars are not suitable. One by one, the US agency is announcing projects and vehicle concepts that should serve to fulfill this mission. The latest concept is called SWIM (Sensing With Independent Micro-Swimmers), a swarm of mini-submarines to explore under the ice in places like Encédalo or Europa.
Our many marine worlds.
The solar system has several “underwater worlds”. There is no exact definition, but they are planets, satellites and other bodies with a rocky core but covered by a layer of at least partially liquid water. Places like Encédalo, Europa and Pluto itself are suspected of harboring this type of extraterrestrial oceans. NASA has been wanting to explore them for years.
The search for life.
The reason is that these aquatic regions can tell us a lot about the origin of life. The seafloor of these planets could be riddled with geological activity. The water of the oceans would be absorbed and heated by the rocks, generating a multitude of chemical reactions. The mineral-laden water would rise through underwater geysers and return to the mineral-laden ocean.
The microbes would take advantage of these nutrients and energy and in turn would serve as food for other larger organisms. No other source of energy than that of chemical reactions would be necessary, not even sunlight. Chemosynthesis, as it is called, occurs on Earth and could occur elsewhere in the solar system.
Beyond the curiosity to know if these places harbor extraterrestrial life, the exploration of these regions could tell us a lot about how life arose on our own planet since the conditions could not be very different from those of the original Earth.
Heat for life.
The subsoil heat of Encédalo and Europa not only generates the energy that life would require to make its way, it would also allow the existence of the water deposits in which it would appear. The cause of this heating would not be exactly the same as that of our planet, but it would be the effect of the tides, that is, the interaction between the gravity of their respective planets and their own mass.
Robots and submarines.
NASA has spent years devising how to explore these oceans in situ. The last of the designs that has been considered has a difference from the rest, replacing a submarine with a swarm of underwater vehicles the size of a mobile deployed from a mother vehicle.
The minisubs would be triangular in shape, like a hang glider, and have four main components in addition to the propulsion system: battery, communications, sensors, and a main computer. The sensors would analyze the temperature, salinity, acidity and pressure of the water in their environment. The development also considers the possibility of adding sensors to try to detect biomarkers.
The deployment will be done through a structure similar to that of the submarines already projected, which they have called cryobot. This would act as a mothership as well as a drill to break through the ice cap. To carry out this function, it would use a nuclear battery that would radiate heat, melting the ice in its path.
A design with advantages and disadvantages.
This system, explains Samuel Howell, a member of the team that created the concept and a scientist at NASA’s Jet Propulsion Lab (JPL), has the advantage that it allows more surface to be covered than through a single vehicle. He explains the concept by comparing it to the Ingenuity helicopter deployed on Mars, only using a handful of them.
Redundancy would not only allow more territory to be covered, but would also mean greater precision with multiple sensors working at the same time, and could also map the environment and show gradients in temperature or salinity.
Of course, they could not get far from the mothership to be able to transmit the information and because of their reduced battery. This would also mean that they would have to work in the dark and would not be able to transmit images of the ocean around them.
One project among many.
The design has entered Phase II of NASA’s Advanced Innovative Concepts (NIAC) program, which aims to develop cutting-edge technologies and innovative ideas at an early stage. This implies that the development team will receive additional funding to try to get the project off the ground, but it can also be ruled out in favor of other vehicle projects.
Without getting too far ahead.
The project coexists with other more established plans for the exploration of extraterrestrial oceans. One of them is scheduled to launch in 2024: the Europa Clipper mission. This should reach the Jupiter satellite in 2030 to explore it from an orbiting probe.
The SESAME program (Scientific Exploration Subsurface Access Mechanism for Europe), on the other hand, hopes to place an underwater probe to carry out the long-awaited in situ analysis of the satellite. There are currently five projects competing for this mission, including one from JPL itself.
Other NIAC projects.
NIAC doesn’t just have its sights set on ocean worlds. The projects considered under this program are varied, ranging from planting mushrooms on satellites to robotic exploration of Martian caves. Some of those that have caught our attention in recent years go through using a lunar crater as a telescope and managing to cover the distance that separates us from Mars in three days.
They are undoubtedly crazy projects, but these are times when space exploration is marked by this type of risky ideas. It is a matter of time to know which of them end up bearing fruit.
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