Background
In situ measurements of the chemical and physical properties of the giant planet atmospheres are needed to address science prioritized in the 2022 Planetary Science and Astrobiology Decadal Survey. Atmospheric descent probes capable of acquiring such data are specified in one of the mission themes in NASA’s New Frontiers $1B class line (“Saturn Probe”) and as part of the next NASA planetary flagship mission (“Uranus Orbiter and Probe”, UOP). Descent probe measurements of Jupiter’s atmosphere could also be proposed in NASA’s Discovery program. Despite the scientific importance of planetary probe measurements, little heritage currently exists for building planetary probes and related instrumentation. The knowledge base from prior atmospheric probes (e.g., the Galileo probe into Jupiter in 1995 and Cassini’s Huygens probe into Saturn’s moon, Titan, in 2005) has retired. The only in-development mission with a probe is the DAVINCI mission, led by GSFC; this mission to Venus will launch no earlier than 2031, after the next New Frontiers and Discovery proposal calls. There are few US institutions with the broad technical expertise to become a probe provider, but SwRI is one, having experience in submersibles, in situ compositional measurement, and small spacecraft.
Approach
The EPIC Presidential Discretion Internal Research (PDIR) project was proposed to cover four main tasks as summarized below:
Task 1: Science & Data Requirements
Task 2: Entry Probe Mission Design
Task 3: Instrument Design Development
Task 4: Pressure Vessel Feasibility Study
Accomplishments
This PDIR commenced work in March 2025 and is scheduled to last two years so at this time we are early in our work effort. The accomplishments to date are summarized below.
Task 1: Science & Data Requirements
Work is completing on a generic Science Traceability Matrix (STM) for Gas and Ice giant planets with an emphasis on Saturn as there is likely a near-term NASA opportunity to propose for a Saturn entry probe. The STM establishes requirements for the technical team to define instrumentation capabilities, data volumes and transmission needs, and atmospheric sampling rates and depths.
Task 2: Entry Probe Mission Design
Mission design is a deferred task but the team has started to explore entry system needs and capabilities for the probe. As this is very mission specific we are using a mission profile to Saturn as our present design reference mission for this study.
Task 3: Instrument Design Development
Baseline and threshold instruments have been defined as a result of the STM work accomplished above in Task 1. Instrument providers are engaged in the PDIR and have started to take measurement requirements defined in the STM to architect the instrument designs and capabilities compatible with the mass, power, volume constraints imposed by accommodation with the descent module.
Task 4: Pressure Vessel Feasibility Study
The pressure vessel team (i.e., the descent module structural element) has completed a literature search on entry probe developments and initiated some early analytic studies to assess descent module structural designs and masses as a function of sampling depth in the atmosphere. Initial studies have begun to assess optimized methods for perforating the descent module walls to allow for the science instruments to access and sample the exterior atmosphere during descent.