Planetary Science Division / Science Mission Directorate
Scientific Exploration Subsurface Access Mechanism for Europa (SESAME)
SESAME supports the formulation and maturation of system concepts and the associated technologies capable of accessing liquid water by penetrating the surface ice.
- Identify ice penetration systems capable of facilitating the detection of evidence of life by providing access to liquid water located 100s of meters to 10s of kilometers below the surface of the ice.
- Identify the technology component(s) representing the greatest technical risk to the overall penetration system.
- Reduce the identified key component technology risks through the proposed development effort.
- Develop prototype hardware and assess the hardware performance via analysis and complementary experiments.
Detailed Summary of Selected SESAME Proposals
0001 – Stone Aerospace
- The primary means of ice penetration is closed-cycle hot water drilling (CCHWD).
- Design, develop, and test a CCHWD cryobot that is compatible with a small fission reactor.
- Will test a functional subscale CCHWD cryobot, and various subsystems, in pure and dirty ice in onsite facility.
0002 – John Hopkins
- Will test multiple communication tether designs bringing at least one approach to TRL 4/5.
- Characterize strength and performance for various tethers and their deployment mechanisms in a laboratory setting.
- Model Europa’s thermo-mechanical environmental hazards that could pose risks to probe-lander communications.
- Evaluate system performance of RF, acoustic, and optical free-space communication strategies.
0003 – Honeybee Robotics
- Hybrid, thermomechanical drill system combining thermal (melting) and mechanical (cutting) penetration approaches.
- Iterative subsystem breadboard development will follow first-order architecture design and identification of critical technologies.
- Empirical results will be used to validate models before designing and testing TRL 4 hardware.
0004 – JPL
- Proposed architecture incorporates kilopower into a high pressure vessel and uses waste heat to penetrate the ice.
- The Cryobot combines multiple ice penetration technologies (melting, water jetting, cutting, and mechanical drilling).
- Cryobot architecture would be matured to TRL 5 using an iterative process involving the development of numerical models validated with complimentary experiments.
0009 – Georgia Tech
- Leveraging Antarctic experience with Icefin and DORA to migrate the terrestrial hardware to a flight-appropriate implementation.
- Adapt Icefin to an encapsulated monolithic body with a hybrid thermomechanical drill.
- Validated the materials list and integration plan by identifying promising technologies, and technical risks.
- Conclude with a TRL 4 subsurface access drill design with tested mechanical drilling capability in ice.
Assumed Constraints for SESAME
Assumptions for NASA-Provided Assets
- A NASA-provided lander will deliver the SESAME penetration system to the surface
- The lander will provide a communication relay between Earth and the SESAME penetration system
- Proposers should assume the use of one of two NASA-provided nuclear power systems manifested along with the SESAME penetration system
- A small fission reactor providing 420 We and 43,000 Wth waste heat
- A radioisotope power system providing up to 110 We and 2,000 Wth waste heat
SESAME Penetration System Details & Constraints
- The system-level ice penetration system must be capable of penetrating an ice sheet and reaching up to 15 km within three years
- The total system mass must be less than 200 kg
- The system must be capable of starting and operating for up to three years in the targeted relevant environment
- Cryogenic temperatures, hard vacuum, high radiation, etc.
- The system must be reliable & minimize the probability of failure due to hardware malfunction or the inability to make forward progress due to the penetration system being stalled during penetration
- The system must be able to progress through realistic ice profiles expected on Europa
- Cryogenic brittle ice near the surface & warmer ductile ice at greater depths
- Dirty ice mixtures containing salts, sulfuric acids, and other materials
- “Pockets” with subsurface voids and liquid water reservoirs