Options for staging orbits in cislunar space

Abstract

NASA has been studying options to conduct missions beyond Low Earth Orbit, but within the Earth-Moon system, in preparation for deep space exploration including human missions to Mars. Referred to as the Proving Ground, this arena of exploration activities will enable the development of human spaceflight systems and operations to satisfy future exploration objectives beyond the cislunar environment. One option being considered includes the deployment of a habitable element or elements, which could be used as a central location for aggregation of supplies and resources for human missions in cislunar space and beyond. Characterizing candidate orbit locations for this asset and the impacts on system design and mission operations is important in the overall assessment of the options being considered. The orbits assessed in this paper were previously identified in work conducted by NASA and others. In this paper orbits are assessed for their relative attractiveness based on various factors. First, a set of constraints related to the capability of the combined Orion and Space Launch System (SLS) system to deliver humans and cargo to and from the orbit are evaluated. Second, the ability to support potential lunar surface activities is considered. Finally, deployed assets intended to spend multiple years in the Proving Ground would ideally require minimal station keeping costs to reduce the mass budget allocated to this function. Additional mission design drivers include potential for uninterrupted communication with deployed assets, thermal, communications, and other operational implications. The results of the characterization and evaluation of the selected orbits indicate a Near Rectilinear Orbit (NRO) is an attractive candidate as an aggregation point or staging location for operations. In this paper, the NRO is further described in terms which balance a number of key attributes that favor a variety of mission classes to meet multiple, sometimes competing, constraints.

Spectral Density Method of Liquid Propellant Gauging

“…The following simplified analysis assumes the mission profile presented in "Options for Staging Orbits in Cis-Lunar Space", Ryan Whitley and Roland Martinez [2], represents current Orion plans. This analysis also assumes full Orion ESM prop tanks at first lunar flyby per Whitley/Martinez and assumes propellant and oxidizer drain at the same rate.…”

Science on the lunar surface facilitated by low latency telerobotics from a Lunar Orbital Platform - Gateway

“…The Gateway will also have similar capabilities as the Mars orbiters, including Mars Reconnaissance Orbiter, Mars Odyssey, and MAVEN, which provide communications between the Mars rovers and Earth [9]. With the currently planned Near Rectilinear Halo Orbit (NRHO), the Gateway will be in a position to provide more than 60% communication coverage for a large portion of the lunar far side, which is greater than the relay support coverage provided by the current Mars fleet [10]. In addition, the LOP-G could provide a range of other surface mission support services, including remote sensing and imaging, "orbital computing" (high-performance computation and data storage similar to terrestrial "cloud computing"), positioning, and timing.…”

Traverses for the ISECG-GER design reference mission for humans on the lunar surface

“…Though not pursued in this study, another feasible option is to place the LOP-G into a Near Rectilinear Halo Orbit (NRHO) using DRM architecture from Whitley et al (2017). If the NRHO were selected as the orbital configuration for the LOP-G in this study up to 86% coverage for all landing sites would be possible (Whitley and Martinez, 2016), an improvement of up to 2% coverage at four of the five proposed landing sites. While the NRHO is comparable to the large and small halo configurations in terms of propellant cost, this configuration offers additional advantages in that it has very short transfer times (0.5 day vs 3 days for an EM-L2 halo), reducing crew time on the landing vehicle, decreasing the mass required for air, supplies and related systems, and allowing for an increase in propellant mass (Whitley et al, 2017).…”