timing, Wood stated that advancements in SWAP for existing capabilities/components should be technologies in themselves, and should be reflected in the roadmap alongside new capabilities. He stated that any game-changing capability would likely result from evolutionary advances with existing technologies, rather than revolutionary technologies.

Wood’s assessment of the top technical challenges (within the frequency and timing section of the roadmap) include improvements in high-performance clocks (stability, SWAP, and reliability), oscillators, and space qualified lasers. These imply high-priority technology advancements in (1) improving frequency and timing reference sources by advancing the TRL, making SWAP advancements, and improving reliability, and (2) making reliability and SWAP improvements (rather than improving performance) for optical metrology hardware. Mercury ion atomic clocks were identified as a component technology near a tipping point, and neutrino navigation was identified as unfeasible on any kind of realistic development timescale.

During the question and discussion phase, Wood recommended that NASA place navigation beacons around places of interest and locations that will be visited at higher frequencies, such as the Moon, Mars, Titan, and other locations.

Briefing 6: Mission Design and Navigation

Alberto Cangahuala (JPL) provided inputs on the roadmap’s treatment of navigation for lunar and interplanetary applications. In this area, Cangahuala identified top technical challenges as: (1) high-fidelity modeling to mitigate the impact of long round-trip light times on numerical precision, (2) reducing onboard resources (mass, power, and delta-V) required for guidance and navigation, and (3) boot-strapping required to accrue necessary detailed environmental characterization information for target bodies. He also identified several trends for modern navigation systems, including the challenges of route planning for low-thrust systems, low-energy transfers, proximity operations, satellite and planetary tours, and operations in unstable and/or unknown dynamical environments. As a result of these trends, modern missions require a stronger integration of flight path and attitude control (i.e., coupling of control knowledge and thrust), highlighting the need for more onboard autonomy (both fully integrated systems and navigation “apps” that take advantage of existing flight system capabilities).

Cangahuala identified mission/trajectory design as a potential technology gap in the roadmap. This is a cross-cutting capability with parts in modeling and simulation and navigation. Navigation and mission/trajectory design are connected by a common need for consistent modeling for planetary and spacecraft dynamics, and mission/trajectory design can minimize navigation uncertainties as part of a design process. Within this field, high-priority challenges include improving the speed, agility, and robustness of trajectory optimizers and investigating new trajectory mechanisms (e.g., invariant manifolds, cycler trajectories).

Public Comment and Discussion Session

The following are views expressed during the public comment and discussion session by either presenters, members of the panel, or others in attendance.

•   Synergy with DOD investments. Some technologies in the roadmap may be synergistic with elements in the DOD. This includes a near-term experiment on atmospheric dynamics, knowledge about space-based IP-networking (though information assurance is a challenge), specific TWTA and SSPA component technologies, and minimization of SWAP for existing technologies. While some of these were tied to the now-cancelled TSAT program, other efforts in these areas are ongoing. NASA and DOD may benefit from working together on these technologies, or at least remaining cognizant of developments made by the other organization. NASA was encouraged to participate in the Space Industrial Council’s Critical Technologies Working Group, which addresses inter-agency technology development efforts. This could be a mechanism for NASA to communicate with their DOD counterparts and identify high-TRL development items that NASA could productize to claim early successes for OCT.

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