NASA’s Lucy Mission to Explore Trojan Asteroids Remains on Cost, Schedule

An artist’s concept of the Lucy Mission. (Credit: SwRI)

by Douglas Messier
Managing Editor

NASA’s Lucy mission to explore a group of Trojan asteroids orbiting in tandem with Jupiter remains on cost and schedule for a November 2021 launch, according to a new assessment from the Government Accountability Office (GAO).

The $981.1 million project has experienced challenges with the development of the spacecraft’s guidance system and solar panels, but actions have been taken to mitigate the impacts on cost and schedule.

“Lucy is tracking a risk related to a discovery that the contractor built the software for the guidance, navigation, and control system (GN&C) based on perfect knowledge of the binary orbit, or relative position of the two Trojans with regard to one another, which the project does not have,” GAO said.

The program is performing additional ground- and space-based observations of the targeted asteroids and completing a new algorithm capable of processing information from two orbiting bodies, the assessment stated.

This diagram illustrates Lucy’s orbital path. The spacecraft’s path (green) is shown in a frame of reference where Jupiter remains stationary, giving the trajectory its pretzel-like shape. After launch in October 2021, Lucy has two close Earth flybys before encountering its Trojan targets. In the L4 cloud Lucy will fly by (3548) Eurybates (white) and its satellite, (15094) Polymele (pink), (11351) Leucus (red), and (21900) Orus (red) from 2027-2028. After diving past Earth again Lucy will visit the L5 cloud and encounter the (617) Patroclus-Menoetius binary (pink) in 2033. As a bonus, in 2025 on the way to the L4, Lucy flies by a small Main Belt asteroid, (52246) Donaldjohanson (white), named for the discoverer of the Lucy fossil. After flying by the Patroclus-Menoetius binary in 2033, Lucy will continue cycling between the two Trojan clouds every six years. (Credits: Southwest Research Institute)

Project officials are also concerned that foam particles from cushions used to dampen launch vibrations on Lucy’s solar panels could contaminate mirrors and instrument sensors.

“The project is testing samples of the cushion to better understand how to reduce the number of particles it generates and inform cleaning recommendations,” the report said.

GAO’s assessment of the Lucy mission follows.

NASA: Assessments of Major Projects
Report to Congressional Committees

Government Accountability Office
April 2020

Lucy

Lucy will be the first mission to investigate the Trojans, which are a population of never-explored asteroids orbiting in tandem with Jupiter. The project aims to understand the formation and evolution of planetary systems by conducting flybys of these remnants of giant planet formation.

The Lucy spacecraft will first encounter a main belt asteroid—located between the orbits of Mars and Jupiter—and then will travel to the outer solar system where the spacecraft will encounter six Trojans over an 11-year mission. The mission’s planned measurements include asteroid surface color and composition, interior composition, and surface geology.

Project Summary

Lucy continues to operate within its cost and schedule baselines. The project’s launch vehicle costs $12.9 million less than estimated, so NASA moved these savings to development and operational cost reserves. Project officials stated that they are retaining adequate schedule reserves to mitigate current difficulties faced with vendors, as well as other risks, and plan to hold to their committed launch readiness date of November 2021.

The project held its critical design review in October 2019. Lucy continues to track issues with its solar array development, the schedule for which had experienced significant erosion, but officials report that strategies are in place to mitigate the factors that contributed to the schedule delays.

Credit: GAO

Project officials also stated that mitigations are in place to manage risks the project is tracking relating to its ability to achieve baseline science requirements dependent on its guidance, navigation, and control system.

Cost and Schedule Status

The Lucy project continues to operate within its cost and schedule baselines. In January 2019, NASA selected a launch vehicle for Lucy, which costs $12.9 million less than the project estimated at the time it established its cost baseline.

NASA allocated $4.9 million of these savings to development cost reserves and the remaining $8.0 million to operations cost reserves. As a result, the overall life cycle cost estimate remains unchanged.

The Lucy project has experienced challenges with the solar array schedule, but as of February 2020, project officials stated that the schedule has held to the plan established at the October 2019 mission critical design review.

Further, the project was holding schedule reserves as planned in accordance with NASA center policy. Multiple factors including issues with fabrication and component qualification testing at the contractors contributed to the schedule challenges.

Project officials reported that they have established mitigations to manage schedule delays. For example, the contractor in charge of integrating the solar array onto the spacecraft has modified the flow of assembly, test, and launch operations to accept delivery as late as January 2021 to still support a launch date of November 2021.

Also, the project reported that subcontractors have made some progress in addressing fabrication and qualification issues and are implementing second shift and weekend operations where feasible to make up for delays.

Design

Lucy held its critical design review in October 2019 with approximately 85 percent of design drawings released, which is slightly below the best practice of releasing 90 percent of design drawings at this review. Project officials stated that they primarily use this metric to assess schedule performance, which remains on target to meet their baseline.

Our reviews of NASA and Department of Defense projects have found that knowledge that a project’s design can be manufactured helps ensure that targets for cost and schedule will be met.

Technology

Lucy is tracking a risk related to a discovery that the contractor built the software for the guidance, navigation, and control system (GN&C) based on perfect knowledge of the binary orbit, or relative position of the two Trojans with regard to one another, which the project does not have.

Officials stated that the project is currently mitigating this risk through assessment of existing observations and additional ground and space-based observation and plans to complete an algorithm capable of processing information from two orbiting bodies in March 2020.

Another risk to science requirements connected to the GN&C system is the risk that uncertainty in the shape of the target asteroid could mean that the spacecraft cannot point itself adequately to collect data.

The project continues to carry out mitigation procedures, such as assessing when the best times to take science measurements are given difficulties in spacecraft pointing relative to its targets.

Lucy is tracking an additional risk to the solar array that could degrade science capabilities. Specifically, foam particles from the cushions used to dampen launch vibration and prevent sticking during deployment could contaminate mirrors and instrument sensors, degrading science capabilities. The project is testing samples of the cushion to better understand how to reduce the number of particles it generates and inform cleaning recommendations.