View source for Astronomy:Near-Earth Asteroid Scout

{{Short description|Solar sail spacecraft}}
{{Infobox spaceflight
| name              = Near-Earth Asteroid Scout
| names_list        = NEA Scout
| image             = Near Earth Asteroid Scout.jpg 
| image_caption     = NEA Scout concept: a controllable [[Engineering:CubeSat|CubeSat]] [[Physics:Solar sail|solar sail]] spacecraft
| image_size        = 300px

| mission_type      = [[Engineering:Technology demonstration|Technology demonstrator]], Reconnaissance
| operator          = [[Organization:NASA|NASA]]
| COSPAR_ID         = 2022-156H
| SATCAT            = 57684
| website           = 
| mission_duration  = 2.5 years (planned)<br/>{{time interval|16 November 2022 06:47:44|19 November 2022}} (final)

| spacecraft_type   = [[Engineering:CubeSat|CubeSat]]
| spacecraft_bus    = [[Engineering:CubeSat|6U CubeSat]]
| manufacturer      = 
| launch_mass       = {{cvt|14|kg}} <ref name="Sobey 2016"/> 
| dimensions        = {{cvt|10|×|20|×|30|cm}}<br/>Solar sail: {{cvt|85|m2}} <ref name="FTU"/>
| power             =

| launch_date       = 16 November 2022, 06:47:44 UTC<ref name="reuters 1">{{Cite news |last1=Roulette |first1=Joey |last2=Gorman |first2=Steve |date=2022-11-16 |title=NASA's next-generation Artemis mission heads to moon on debut test flight |language=en |work=Reuters |url=https://www.reuters.com/lifestyle/science/nasas-artemis-moon-rocket-begins-fueling-debut-launch-2022-11-15/ |access-date=2022-11-16}}</ref>
| launch_rocket     = [[Astronomy:Space Launch System|SLS Block 1]]
| launch_site       = KSC, [[Astronomy:Kennedy Space Center Launch Complex 39B|LC-39B]]<ref name="HEOC">{{cite web|url=https://www.nasa.gov/pdf/630149main_5-Hill_SLS%20MPCV%20GSDO_508.pdf |title=NASA Advisory Council - Exploration Systems Development Status|last=Hill|first=Bill|publisher=NASA|date=7 March 2012|access-date=11 March 2021}} {{PD-notice}}</ref>
| launch_contractor = [[Organization:NASA|NASA]]

| deactivated       = 
| last_contact      = Never established

| orbit_reference   = [[Astronomy:Heliocentric orbit|Heliocentric orbit]] 
| orbit_regime      = 
| orbit_periapsis   = 
| orbit_apoapsis    = 
| orbit_inclination = 
| orbit_period      = 
| apsis             = helion

| trans_band        = [[Physics:X band|X-band]] 
| trans_TWTA        = 2 [[Watt|watt]]s

| insignia          = NEA Scout Logo.png
| insignia_caption  = NEA Scout Mission Patch
| insignia_size     = 200px

| programme         = 
| previous_mission  = 
| next_mission      = 
}}

The '''Near-Earth Asteroid Scout''' ('''NEA Scout''') was a mission by [[Organization:NASA|NASA]] to develop a controllable low-cost [[Engineering:CubeSat|CubeSat]] [[Physics:Solar sail|solar sail]] spacecraft capable of encountering [[Astronomy:Near-Earth object|near-Earth asteroid]]s (NEA).<ref name="TechPort">{{cite web|title=NASA TechPort – Near Earth Asteroid Scout (NEA Scout)|url=https://techport.nasa.gov/view/14656|work=NASA TechPort|publisher=NASA|date=2015|access-date=11 March 2021|archive-date=29 November 2020|archive-url=https://web.archive.org/web/20201129163220/https://techport.nasa.gov/view/14656|url-status=dead}} {{PD-notice}}</ref><ref name="McNutt">{{cite web|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140012882.pdf|title=Near-Earth Asteroid Scout|last1=McNutt|first1=Leslie |last2=Castillo-Rogez|first2=Julie|publisher=NASA|work=American Institute of Aeronautics and Astronautics (AIAA)|date=4 August 2014|access-date=11 March 2021}} {{PD-notice}}</ref> NEA Scout was one of ten CubeSats launched into a [[Astronomy:Heliocentric orbit|heliocentric orbit]] on [[Engineering:Artemis 1|Artemis 1]], the maiden flight of the [[Astronomy:Space Launch System|Space Launch System]], on 16 November 2022.<ref name="reuters 1"/><ref>{{cite web |last=Clark |first=Stephen |url=https://spaceflightnow.com/2021/10/12/adapter-structure-with-10-cubesats-installed-on-top-of-artemis-moon-rocket/ |title=Adapter structure with 10 CubeSats installed on top of Artemis moon rocket |work=Spaceflight Now |date=12 October 2021 |access-date=22 October 2021}}</ref>

The target for the mission was asteroid 2020 GE,<ref name="JPL">{{cite web |url=https://www.jpl.nasa.gov/news/nasa-solar-sail-mission-to-chase-tiny-asteroid-after-artemis-i-launch |title=NASA Solar Sail Mission to Chase Tiny Asteroid After Artemis I Launch |author=<!--Not stated--> |date=20 January 2022 |website=Jet Propulsion Laboratory |publisher=NASA |access-date=20 January 2022 |quote=The target is 2020 GE, a near-Earth asteroid (NEA) that is less than {{convert|60|ft|m|abbr=off|sp=us}} in size.}}</ref> but this could have changed based on launch date or other factors.<ref name="NASANEAScout">{{cite web|last1=Mahoney|first1=Erin|title=NEA Scout|url=https://www.nasa.gov/content/nea-scout|publisher=NASA|date=14 January 2020|access-date=11 March 2021}} {{PD-notice}}</ref> After deployment, NEA Scout was to perform a series of lunar flybys to achieve optimum departure trajectory before beginning its two-year-long cruise.

No contact with the spacecraft was ever made, and the mission was lost.<ref name="Dickinson2022">{{cite news|url=https://skyandtelescope.org/astronomy-news/status-update-artemis-1s-smallsat-missions/|title=Status Update: Artemis 1's SmallSat Missions|date=6 December 2022|first=David|last=Dickinson|newspaper=Sky & Telescope |publisher=Sky&Telescope|access-date=8 December 2022}}</ref>

== Overview ==
The mission was funded by NASA's Human Exploration and Operations Mission Directorate. Near-Earth asteroids ([[Astronomy:Near-Earth object|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 {{cvt|20|m}} in diameter is also of great relevance to plan mitigation strategies for [[Astronomy:Asteroid impact avoidance|planetary defense]].<ref name="McNutt"/>

NASA's [[Organization:Marshall Space Flight Center|Marshall Space Flight Center]] (MSFC) and [[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]] (JPL) jointly developed this mission with support from NASA's [[Organization:Goddard Space Flight Center|Goddard Space Flight Center]] (GSFC), Lyndon B. Johnson Space Center (JSC), [[Organization:Langley Research Center|Langley Research Center]] (LRC), and NASA Headquarters.<ref name="TechPort" /> The principal investigator (science) was Julie Castillo-Rogez from NASA's JPL. The principal investigator was Les Johnson from NASA MSFC.

== Goal ==
The NASA Near Earth Asteroid (NEA) Scout mission was going to demonstrate the capability of an extremely small spacecraft, propelled by a solar sail, to perform reconnaissance of an asteroid at low cost. The goal was to develop a capability that would close knowledge gaps at a [[Astronomy:Near-Earth object#Near-Earth asteroids|near-Earth asteroid]] in the 1–100 m range.<ref name="McNutt"/><ref name="Castillo">{{cite web |url=http://www.lpi.usra.edu/sbag/meetings/jul2014/presentations/0930_Thu_Castillo_NEAScout.pdf|title=Near Earth Asteroid Scout Mission|last1=Castillo-Rogez|first1=Julie|last2=Abell|first2=Paul|work=NASA |publisher=Lunar and Planetary Institute|date=July 2014|access-date=11 March 2021}} {{PD-notice}}</ref><ref name="Johnson 2017"/> 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.<ref name="McNutt"/>

The mission researchers argued 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 was near-Earth asteroid 2020 GE.<ref name="JPL" /> The asteroid made a close approach to Earth in September 2023 of around 5.7 million kilometres, which was when NEA Scout was scheduled to make its flyby.<ref name="JPL" /> The spacecraft would have approached the asteroid at less than a mile distant, and make the slowest flyby of any asteroid by any spacecraft at less than 30&nbsp;m/s. A 14 megapixel camera, the mission's sole instrument, was going to image the object at very high resolutions of up to 10&nbsp;cm/pixel.

2020 GE is no more than 18 meters across, and would have been the smallest object yet explored by spacecraft.<ref name="JPL" />

== Status ==
As of 17 November 2022, NEA Scout was one of two out of the ten cubesats released by Artemis I whose status remained unknown.<ref name="Messier">{{Cite web|url=https://parabolicarc.com/2022/11/17/status-report-on-artemis-i-secondary-cubesat-payloads/|title=Status Report on Artemis I Secondary CubeSat Payloads|date=17 November 2022|access-date=18 November 2022|first=Doug|last=Messier|website=parabolicarc.com}}</ref> Communications with the spacecraft had not been established as of 18 November 2022, two days after launch.<ref name="IssamAhmed">{{Cite tweet |author=Issam Ahmed |user=IssamAhmed |number=1593427262032039936 |title=Was asking for an update on a cool side project from the Artemis 1 mission called NEA Scout, a small spaceship that sails on sunshine and is supposed to do recon of an asteroid. Turns out JPL hasn't yet established contact so it may be in trouble. Hope they get it going!|quote=Thank you for your patience, Isaam. Here's a statement on NEA Scout's status: Following successful separation and deployment from the Space Launch System on Nov.16, NASA's Near-Earth Asteroid Scout (NEA Scout) project team has not yet established communications with the spacecraft. Teams continue working to initiate contact with NEA Scout. NEA Scout is a secondary payload for Artemis I and is a completely independent spacecraft. Orion is still on its way to the Moon. Updates will be provided as soon as possible on NASA's Artemis blog.|date=18 November 2022}}</ref>

As of December 2022, NEA Scout was considered lost, after deployment of its solar sail had failed and contact could not be established.<ref name="Dickinson2022"/>

== Payload ==
Observations would have been achieved using a [[Engineering:CubeSat|CubeSat]] performing a close (~10&nbsp;km) flyby, equipped with a high resolution science-grade monochromatic camera to measure the physical properties of a near-Earth object. The camera was a custom JPL design.<ref name=":0">{{Cite book|last1=Lightholder|first1=Jack|last2=Thompson|first2=David R.|last3=Castillo-Rogez|first3=Julie|last4=Basset|first4=Christophe|title=2019 IEEE Aerospace Conference |chapter=Near Earth Asteroid Scout CubeSat Science Data Retrieval Optimization Using Onboard Data Analysis |date=March 2019|chapter-url=https://ieeexplore.ieee.org/document/8742190|pages=1–7|doi=10.1109/AERO.2019.8742190|isbn=978-1-5386-6854-2 |s2cid=195222320 }}</ref> The electronics were based on the context camera design for the [[Engineering:Orbiting Carbon Observatory 3|Orbiting Carbon Observatory 3]] (OCO3) instrument<ref>{{Cite book|last1=McKinney|first1=Colin|last2=Goodsall|first2=Timothy|last3=Hoenk|first3=Michael|last4=Shelton|first4=Jacob|last5=Rumney|first5=Keith|last6=Basset|first6=Christophe|last7=Jeganathan|first7=Muthu|last8=Moore|first8=Douglas|title=2018 IEEE Aerospace Conference |chapter=Context cameras for the Orbiting Carbon Observatory 3 (OCO-3) instrument |date=March 2018|chapter-url=https://ieeexplore.ieee.org/document/8396759|pages=1–15|doi=10.1109/AERO.2018.8396759|isbn=978-1-5386-2014-4 |s2cid=49540174 }}</ref> with a custom firmware, a ruggedized commercial lens and a fully re-designed enclosure.<ref name=":0"/> The measurements to be addressed included 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.<ref name="McNutt"/> The mission used NASA's Deep Space Network as the primary component for communications and tracking.<ref name="McNutt"/>

== Design ==
The spacecraft architecture, first presented in 2014, was based on a 6-unit CubeSat with a stowed envelope slightly larger than 10 × 20 × 30&nbsp;cm, a mass of {{cvt|14|kg}},<ref name="Sobey 2016"/> [[Engineering:Cold gas thruster|cold gas thruster]] system,<ref name="VACCO">{{cite web|url=https://cubesat-propulsion.com/nea-scout-propulsion-system/|title=NEA Scout Propulsion System|publisher=VACCO|date=2021|access-date=11 March 2021}}</ref> and was primarily based on the use of commercial off-the-shelf parts.<ref name="McNutt"/> While it is possible for a 6U CubeSat to reach an NEA with conventional [[Astronomy:Spacecraft propulsion|chemical propulsion]], both the number of targets and the launch window would be tightly constrained. By utilizing [[Physics:Solar sail|solar sail]] propulsion, intercepting a large number of targets in any launch window is made possible.<ref name="Sobey 2016">{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160008143.pdf|title=Design and Development of NEA Scout Solar Sail Deployer Mechanism|author1=Alexander R. Sobey |author2=Tiffany Russell Lockett |publisher=NASA|date=4 May 2016|access-date=11 March 2021}} {{PD-notice}}</ref> The mission duration was estimated at 2.5 years.<ref name="FTU">{{cite web|url=https://ntrs.nasa.gov/citations/20190030404 |title=Lessons Learned from the Flight Unit Testing of the Near Earth Asteroid Scout Flight System|publisher=NASA NTRS|date=30 July 2019|access-date=12 March 2021}} {{PD-notice}}</ref>

After deployment in [[Astronomy:Outer space#Cislunar space|cislunar space]], NEA Scout was intended to deploy its [[Physics:Solar panels on spacecraft|solar panels]] and antenna. Following a [[Engineering:Flyby (spaceflight)|lunar flyby]], the solar sail would have deployed and spacecraft checkout would have begun. NEA Scout would then have performed 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.<ref name="Johnson 2017">{{cite web|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170001499.pdf|title=Near Earth Asteroid (NEA) Scout|author1=Les Johnson |author2=Julie Castillo-Rogez |author3=Jared Dervan |author4=Leslie McNutt |publisher=NASA|date=17 January 2017|access-date=11 March 2021}} {{PD-notice}}</ref>

;Sail
Four 6.8 m booms were designed to deploy the single 85 m<sup>2</sup> [[Chemistry:Polyimide|aluminized polyimide]] solar sail, which is 2.5 μm thick. The sail deployment mechanism was a modification of those of [[Engineering:NanoSail-D|NanoSail]] and [[Organization:The Planetary Society|The Planetary Society]]'s [[Engineering:LightSail|LightSail 2]] spacecraft.<ref name="Sobey 2016"/><ref name="Johnson 2017"/> The deployment time for the full sail was planned to be approximately 30 minutes.

;Avionics
The avionics module accommodated the printed circuit boards for telecommunications, power distribution unit, command and data handling system, Sun sensors, and a miniaturized [[Astronomy:Star tracker|star tracker]]. This module also included [[Engineering:Reaction wheel|reaction wheel]]s, lithium batteries, and a camera.<ref name="McNutt"/> The solar sail spacecraft [[Astronomy:Spacecraft attitude control|attitude control]] system consisted of three actuating subsystems: a reaction wheel control system, a reaction control system, and an adjustable mass translator system.<ref name="Flex">{{cite web|url=https://ntrs.nasa.gov/search.jsp?R=20170001505|title=Flex Dynamics Avoidance Control of the NEA Scout Solar Sail Spacecraft's Reaction Control System|author=Heaton Andrew|publisher=NASA|date=17 January 2017|access-date=11 March 2021}} {{PD-notice}}</ref>

;Propulsion
The cold gas propulsion system was situated below the solar sail and provides detumbling, initial impulsive maneuvers (required for lunar-assisted escape trajectories), and momentum management.<ref name="VACCO"/>

;Communications
The spacecraft used the Iris transponder for communications in the [[Astronomy:X-band|X-band]].<ref name="McNutt"/>

;Power
Photovoltaic solar panels, with rechargeable batteries. <!-- dimensions ? Watts ? Voltage ? -->

{{multiple image | align = center | direction = horizontal | width = 300
| header = Animation of NEA Scout's planned trajectory
| image1 = Animation of NEA Scout around Sun.gif
| caption1 = Around the Sun
| image2 = Animation of NEA Scout around Earth before beginning cruise to 2020 GE.gif
| caption2 = Around the Earth before beginning cruise to 2020 GE
|image3 = Animation of NEA Scout around Earth.gif
|caption3 = Around the Earth
| footer = {{legend2|Yellow|Sun}}{{·}}{{legend2| RoyalBlue |Earth}}{{·}}{{legend2| Magenta| NEA Scout}}{{·}}{{legend2|Cyan|2020 GE}}{{·}}{{legend2|Lime|Moon}}
}}

== See also ==
* [[Astronomy:List of missions to minor planets|List of missions to minor planets]]

;Solar sail spacecraft
* {{annotated link|Astronomy:Breakthrough Starshot}}
* {{annotated link|Engineering:IKAROS}}
* {{annotated link|Engineering:Sunjammer (spacecraft)}}

;Other deep space CubeSats
* {{annotated link|Astronomy:Mars Cube One}} sent with Insight

;The 10 [[Engineering:CubeSat|CubeSat]]s flying in the [[Engineering:Artemis 1|Artemis 1]] mission
* Near-Earth Asteroid Scout by [[Organization:NASA|NASA]], a [[Physics:Solar sail|solar sail]] spacecraft that was planned to encounter a [[Astronomy:Near-Earth object|near-Earth asteroid]] (mission failure)
* [[Astronomy:BioSentinel|BioSentinel]], an [[Astronomy:Astrobiology|astrobiology]] mission
* [[Astronomy:LunIR|LunIR]] by [[Company:Lockheed Martin Space|Lockheed Martin Space]]
* [[Astronomy:Lunar IceCube|Lunar IceCube]], by the [[Organization:Morehead State University|Morehead State University]]
* [[Astronomy:CubeSat for Solar Particles|CubeSat for Solar Particles]] (CuSP)
* [[Astronomy:Lunar Polar Hydrogen Mapper|Lunar Polar Hydrogen Mapper]] (LunaH-Map), designed by the [[Organization:Arizona State University|Arizona State University]]
* EQUULEUS, submitted by [[Organization:JAXA|JAXA]] and the University of Tokyo
* [[Astronomy:OMOTENASHI|OMOTENASHI]], submitted by JAXA, a lunar lander (mission failure)
* [[Astronomy:ArgoMoon|ArgoMoon]], designed by Argotec and coordinated by [[Organization:Italian Space Agency|Italian Space Agency]] (ASI)
* [[Astronomy:Team Miles|Team Miles]], by Fluid & Reason, LLC. Florida

== References ==
{{Reflist}}

== External links ==

{{Moon spacecraft}}
{{Asteroid spacecraft}}
{{Planetary defense}}

[[Category:Missions to near-Earth asteroids]]
[[Category:NASA space probes]]

{{Sourceattribution|Near-Earth Asteroid Scout}}