Have you heard that NASA will explore and analyze Europa, a moon of Jupiter which NASA believes to have water? The Europa Clipper mission is being executed to do just that. The mission goal is to orbit Jupiter to investigate Europa, based on evidence that this moon has water under the icy crust.
Europa possesses the smoothest surface known of any solid object in the solar system. This visible smoothness and apparent youth of Europa’s surface led researchers to the hypothesis that a water ocean exists beneath the icy crust of the surface and could conceivably lead to extraterrestrial life upon the moon. This ocean is expected to cover the moon, under a thick icy crust, and would contain more water than all of Earth’s oceans combined. Exploration missions of this nature require very unique thermal management considerations. Unlike satellites that operate in a single orbit and have predictable sink conditions, these missions must survive the long trip to Europa, and then remove significant amounts of heat while in Jupiter’s orbit in order to complete the exploration objectives.
In any space application, there is extreme importance on mass, reliability, and power utilization. These areas become paramount on deep space exploration missions where the space vehicle needs to survive launch, use controls/electronics to navigate far distances, and turn on all functional electronics once the destination is reached. A significant range of mechanical and thermal requirements are realized for these types of missions. In traditional satellites, the thermal system relies primarily on passive heat transport and dissipates to the space environment via radiation; this thermal network typically consists of Aluminum-Ammonia CCHPs – lightweight, highly efficient heat transfer devices that require no power for operation. External CCHPs are used to transfer heat from payloads to radiators, and embedded CCHPs are selected to increase radiator efficiency, which is most common in satellites that output significant waste heat. For deep space exploration missions, many other technologies are considered, including:
- Variable Conductance Heat Pipes (VCHP): Serves as a thermal diode to control temperature and limit the need for significant survival heat input.
- Loop Heat Pipes (LHP): High power heat transport, can utilize flex lines. Added cost and complexity.
- Phase Change Material (PCM): Absorb waste heat fluctuations, such that you can size the radiators for average heat load instead of peak heat load.
- Active-Pumped Loops: Provide high heat removal and distance heat transport with added reliability concern and power consumption. Redundant pumps can be used to de-risk pump failure but cost additional mass to implement.
More on the Europa Clipper Mission
The Europa mission will use the clipper for flybys of the moon and will collect data from the surface at certain points within its orbit, without actually landing any crafts upon the surface. The clipper is a very important key part of this mission, so it will be equipped with all the tools necessary to answer the big questions scientists have been asking. Questions such as:
- “Does Europa actually conceal an ocean under that icy shell?”
- ”How deep is this hypothetical ocean?”
- ”Does the chemistry of the ocean seem friendly to microbes?”
- ”Is Europa’s ice shell tectonically active, allowing the moon’s surface material to make its way to the ocean and vice versa, perhaps enriching the ocean with oxygen-rich molecules from above that could serve as “food” for organisms?”
To answer these questions, they will equip the clipper with special cameras that will map the moon’s surface, measure the heights of surface features, produce stereoscopic images, and seek evidence of geologic activity. The spectrometer will be used to study the composition of the surface and particles around it. An ice penetrating radar will push past the icy shell and search for water below the surface. A magnetometer will be included to measure the strength and direction of Europa’s magnetic field, and therefore determine how deep and salty the ocean is. A dust analyzer will be used to analyze fragments of Europa that have been blasted off by micrometeorites. An infrared instrument will record the moon’s surface temperature, as they are looking for warmer parts of the moon in particular. And this is just the beginning! It will be a difficult mission and there will be a variety of tools and instruments equipped on the clipper to ensure the mission can go as smoothly as possible.
Check out ACT’s Research & Development group’s work on an autonomous melting probe for the Europa mission.