The current target for the mission is asteroid 2020 GE,[8] but this may change based on launch date or other factors.[9] After deployment, NEA Scout will perform a series of lunar flybys to achieve optimum departure trajectory before beginning its two-year-long cruise.
Overview
The mission is funded by NASA's Human Exploration and Operations Mission Directorate. Near-Earth asteroids (NEAs) are of interest to science, and as NASA continues to refine its plans to possibly explore these small objects with human explorers, initial reconnaissance with inexpensive robotic precursors is necessary to minimize risks, and inform the required instruments for future reconnaissance missions. The characterization of NEAs that are larger than 20 m (66 ft) in diameter is also of great relevance to plan mitigation strategies for planetary defense.[6]
The NASA Near Earth Asteroid (NEA) Scout mission will demonstrate the capability of an extremely small spacecraft, propelled by a solar sail, to perform reconnaissance of an asteroid at low cost. The goal is to develop a capability that would close knowledge gaps at a near-Earth asteroid in the 1–100 m range.[6][10][11] NEAs in the 1–100 m range are poorly characterized due to the challenges that come with detecting, observing, and tracking these for extended periods of time. It has been thought that objects in the 1–100 m size range are fragments of bigger objects. However, it has also been suggested that these objects could actually be rubble-piles.[6]
The mission researchers argue that "characterization of NEAs that are larger than 20 m in diameter is also of great relevance to inform mitigation strategies for planetary defense".
Target
The planned target, subject to change, is near-Earth asteroid 2020 GE.[8] The asteroid will make a close approach to Earth in September 2023 of around 5.7 million kilometres, which is when NEA Scout is scheduled to make its flyby.[8] The spacecraft will approach the asteroid at less than a mile distant, and make the slowest flyby of any asteroid by any spacecraft at less than 30 m/s. A 14 megapixel camera, the mission's sole instrument, will image the object at very high resolutions of up to 10 cm/pixel.
2020 GE is no more than 18 meters across, and will be the smallest object yet explored by spacecraft.[8]
Payload
Observations will be achieved using a CubeSat performing a close (~10 km) flyby, equipped with a high resolution science-grade monochromatic camera to measure the physical properties of a near-Earth object. The camera is a custom JPL design.[12] The electronics are based on the context camera design for the Orbiting Carbon Observatory 3 (OCO3) instrument[13] with a custom firmware, a ruggedized commercial lens and a fully re-designed enclosure.[12] The measurements to be addressed include target's accurate positioning (position and prediction), rotation rate and pole position, mass, density, mapping of particles and debris field in target vicinity, albedo and asteroid spectral type, surface morphologies and properties, and regolith properties.[6] The mission will use NASA's Deep Space Network as the primary component for communications and tracking.[6]
Design
The spacecraft architecture, first presented in 2014, is based on a 6-unit CubeSat with a stowed envelope slightly larger than 10 × 20 × 30 cm, a mass of 14 kg (31 lb),[2]cold gas thruster system,[14] and primarily based on the use of commercial off-the-shelf parts.[6] While it is possible for a 6U CubeSat to reach an NEA with conventional chemical propulsion, both the number of targets and the launch window would be tightly constrained. By utilizing solar sail propulsion, intercepting a large number of targets in any launch window is made possible.[2] The mission duration is estimated at 2.5 years.[1]
After deployment in cislunar space, NEA Scout will deploy its solar panels and antenna. Following a lunar flyby, the solar sail will deploy and spacecraft checkout will begin. NEA Scout will then perform a series of lunar flybys to achieve optimum departure trajectory before beginning its 2.0 – 2.5 year-long cruise to the asteroid 2020 GE.[11]
Sail
Four 6.8 m booms will deploy the single 85 m2aluminized polyimide solar sail, which is 2.5 μm thick. The sail deployment mechanism is a modification of those of NanoSail and The Planetary Society's LightSail 2 spacecraft.[2][11] The deployment time for the full sail is approximately 30 minutes.
Avionics
The avionics module accommodates the printed circuit boards for telecommunications, power distribution unit, command and data handling system, Sun sensors, and a miniaturized star tracker. This module also includes reaction wheels, lithium batteries, and a camera.[6] The solar sail spacecraft attitude control system consists of three actuating subsystems: a reaction wheel control system, a reaction control system, and an adjustable mass translator system.[15]
Propulsion
The cold gas propulsion system is situated below the solar sail and provides detumbling, initial impulsive maneuvers (required for lunar-assisted escape trajectories), and momentum management.[14]
^ abcdefghiMcNutt, Leslie; Castillo-Rogez, Julie (4 August 2014). "Near-Earth Asteroid Scout"(PDF). American Institute of Aeronautics and Astronautics (AIAA). NASA. Retrieved 11 March 2021. This article incorporates text from this source, which is in the public domain.
^Mahoney, Erin (14 January 2020). "NEA Scout". NASA. Retrieved 11 March 2021. This article incorporates text from this source, which is in the public domain.
^Castillo-Rogez, Julie; Abell, Paul (July 2014). "Near Earth Asteroid Scout Mission"(PDF). NASA. Lunar and Planetary Institute. Retrieved 11 March 2021. This article incorporates text from this source, which is in the public domain.
^ abcLes Johnson, Julie Castillo-Rogez, Jared Dervan, and Leslie McNutt (17 January 2017). "Near Earth Asteroid (NEA) Scout"(PDF). NASA. Retrieved 11 March 2021.((cite web)): CS1 maint: uses authors parameter (link) This article incorporates text from this source, which is in the public domain.
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Cubesats are smaller. Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in brackets).
This article incorporates text from this source, which is in the 
