Challenges in Communications for Exploration Class Missions

Background

Communication latency and channel capacity constraints pose significant challenges to providing medical care beyond low earth orbit (LEO). Developments such as NASA’s Deep Space Optical Communications (DSOC) network provide workable solutions to near-term challenges in channel capacity by utilizing laser (optical) signals in the higher frequency near infra-red spectrum. This network aims to support data transmission at rates 10-100 times higher than currently employed radiofrequency (RF) channel capacities and allow high volume data transfers. Despite such recent advancements however, communication delays and anticipated data downlink limitations - combined with the inability to rapidly return astronauts to Earth in beyond LEO missions - mandate a shift in medical operations towards greater crew autonomy and away from Earth-reliant approaches to medical care.

Description

75 data-producing medical capabilities were identified from among 635 capabilities in NASA’s Information Mission Planning via Analysis of Complex Tradespaces (IMPACT)* database. Data file sizes for each capability were estimated. Channel capacity downlink durations were estimated in the context of a 10% channel capacity allocation for data-generating medical capabilities. Downlink durations varied for each medical capability when examined in the context of current RF capabilities as well as near-term and futuristic optical capabilities.

Discussion

As human space exploration moves toward missions beyond LEO, relying on RF-based communications alone will prove insufficient to sustain the current level of ground-based medical support allocated to LEO missions. Advancements in optical communications such as DSOC offer promise in augmenting transmission capabilities, albeit with undeniable constraints. These constraints include limited allocation of channel capacity supporting medical capabilities, data processing time, SME expert evaluation, and slower uplink compared with downlink rates. In addition to variable latency delays, a fixed speed-of-light limitation must also be considered when assessing the impact of latency on medical operations. Reliance on ground support for clinical decision-making during exploration missions could result in delays measuring in hours or days. While some advancements in technology offer latency mitigation strategies, the concept of Earth Independent Medical Operations (EIMO) will be critical for the future of medical care to crew beyond LEO.