The SLS Saga: The Mothership of the Swarm
***In this Part Four of the SLS Saga, we will explore SLS EM-1’s CubeSat payloads. For additional posts, please visit the SLS Saga Overview microsite here.***
While the Space Launch System (“SLS”) is designed to be a heavy lift launch vehicle capable of achieving the “Horizon Goal,” SLS is also envisioned as a multi-platform rocket that can simultaneously carry out many secondary objectives. One of these goals is SLS’s ability to carry and launch secondary payloads that can advance our knowledge of Deep Space—leading to technological developments that will transform humanity into an interplanetary species.
Some of the key payloads that can accomplish this goal are CubeSats. Miniaturized satellite, CubeSats are named after their physical dimensions: 10x10x11.35 cm cubes that are able to fit 10x10x10 cm of useful volume. Each of these cubes is denominated as 1U in size, and most CubeSats range from 1U to 3U. Originally proposed by Professors Jordi Puig-Suari and Bob Twiggs, CubeSats have become a type of “cost effective platform for science investigations, new technology demonstrations and advanced mission concepts.” Cheaper than standard satellites, these CubeSats have enabled scientists and researchers to accelerate technological advancement by enabling the performance of more high-risk experiments. While CubeSats are making “space science” experiments more readily accessible to the greater community, their popularity is, however, contributing to the space junk problem. Aware of the issue, scientists are now attempting to solve this emerging concern, such as equipping CubeSats with ion thrusters so that they can deorbit and burn up in the Earth’s atmosphere on their own accord.
But for now, CubeSats’ benefits to scientific discovery still outweigh their risks. To this end, NASA is planning to launch several CubeSats (all 6U in size) with SLS’s first mission, Exploration Mission One (“EM-1”). In this post, I will provide an overview of these CubeSats and their mission objectives.
CubeSats on EM-1
As discussed in an earlier SLS Saga post, EM-1’s primary objective is to test SLS’s capabilities for deep-space exploration. But with an ability to launch 70 metric tons (77 tons or 154,000 pounds), SLS will also deploy a baker’s dozen CubeSats on its maiden voyage. These CubeSats were selected through five different means: NASA’s Next Space Technologies for Exploration Partnership, Human Exploration and Operations Mission Directorate, Science Mission Directorate, NASA’s Cube Quest Challenge, and NASA’s international partners.
Next Space Technologies for Exploration Partnership (“NextSTEP”)
NextSTEP is a public-private partnership between NASA and commercial entities that seeks to develop technologies that will extend the duration and capability of missions for deep space exploration. Managed by NASA’s Advanced Exploration Systems Division, NextSTEP chose two CubeSats that will launch on EM-1: Lunar IceCube and SkyFire.
Envisioned by Morehead State University, the Lunar IceCube will be built with an approved NASA funding of up to $7.9 million. Its primary mission is to identify and observe locations of water-ice deposits on the Moon. Lunar IceCube will also study the distribution of such deposits as a function of factors such as time of day, latitude, and lunar soil content. To perform these objectives, the Lunar IceCube will be released from the SLS upon lunar trajectory and will use its ion engine to reach a lunar orbit of 100 km (62 mi) above the lunar surface.
The Skyfire was chosen as an EM-1 CubeSat in February 2016. Designed by Lockheed Martin, the Skyfire received an approved NASA funding of up to $1.4 million. This CubeSat will act as an observer and collect infrared sensor data about the lunar surface while performing a flyby of the Moon. These data will provide scientists with greater understanding for the lunar surface’s “composition, structure, interaction with the space environment, and interaction with solar particles.”
Human Exploration and Operations (“HEO”) Mission Directorate
The HEO Mission Directorate manages NASA’s space operations related to human exploration missions in and beyond low-Earth orbit (“LEO”). This directorate is also in charge of Launch Services, Space Transportation, and Space Communications related to both human and robotic exploration in Outer Space. The HEO Mission Directorate selected three CubeSats on EM-1: BioSentinel, Lunar Flashlight, and Near-Earth Asteroid Scout.
Develop by NASA Ames Research Center, the BioSentinel was selected in 2013. This CubeSat will be inserted into an Earth-trailing heliocentric orbit that will vary between 0.92 to 0.98 times Earth’s distance to the Sun. The BioSentinel’s primary objective is to study the effects of space radiation on biological organisms over long duration missions. 4 of the 6U will hold BioSentinel’s scientific payload, S. cerevisiae (a type of yeast), along with radiation dosimeters and spectrometers. This experiment will measure double-strand breaks (“DSBs”) caused by space radiation on the DNA molecule. The S. cerevisiae yeast was chosen since its DSBs repair mechanism is very similar to that of human cells.
Jointly-managed by the NASA’s Marshall Space Flight Center and the Jet Propulsion Laboratory, the Lunar Flashlight will locate water-ice deposits on the Moon’s permanently shadowed craters. This CubeSat will be launched during SLS’s translunar flight, and will propel itself into a lunar polar orbit. Once at the lunar polar region, the Lunar Flashlight will shine its near infrared lasers onto the surface of these craters with its onboard spectrometer measuring the resulting reflection to identify water-ice deposits. If successful, the Lunar Flashlight will become the first CubeSat to reach the Moon and become the first mission to use laser as a means of searching for water-ice deposits.
Near-Earth Asteroid Scout (“NEA Scout”)
The NEA Scout is also being jointly-designed by Jet Propulsion Laboratory and Marshall Space Flight Center. Deploying shortly after SLS reaches lunar vicinity, the NEA Scout will unfold and use its solar sail as an energy-efficient means of traveling toward a small-size asteroid that is less than 100 meter in size. Although subject to change, the current target is Near-Earth object 1991 VG, which passed within 0.06 AU of Earth on August 7, 2017. NEA Scout’s cruise is expected to last two years, and once it reaches its destination, the CubeSat will take a series of low (50 cm/pixels) and high resolution (10 cm/pixels) images. These images will advance our knowledge of small size asteroids by enabling scientists to learn more about these asteroids’ “orbit, rotation, composition, particular environment, volatile resources, and soil properties,” paving the way for asteroid mining missions in the future. If the NEA Scout succeeds in its mission, it will become the first CubeSat to reach an asteroid.
Science Mission Directorate (“SMD”)
The SMD’s primary mission is to engage United States’ “science community, sponsor scientific research, and develop and deploy satellites and probes in collaboration with NASA’s partners.” The SMD picked two CubeSat missions for EM-1: CuSP and LunaH-Map.
CuSP stands for CubeSat for Solar Particles and will be managed by the Southwest Research Institute. For its mission, CuSP will be placed in a heliocentric orbit and act as a space weather station by measuring solar energetic particles and magnetic fields. Its payload includes a Suprathermal Ion Spectrograph that will measure low-energy solar energetic particles, a Miniaturized Electron and Proton Telescope that will detect high-energy solar energetic particles, and a Vector Helium Magnetometer which will analyze magnetic fields. CuSP will also demonstrate the feasibility of creating a network of space-based weather stations using CubeSats.
Designed by Arizona State University, Lunar Polar Hydrogen Mapper (“LunaH-Map”) will help measure hydrogen deposits at the Moon’s South Pole. This CubeSat will be deployed on a polar orbit around the Moon, and perform 140 low-altitude fly-bys of the South Pole. Its mission will further our knowledge of the amount of water-ice deposits that is tucked away in the permanently shadowed regions of the South Pole.
Cube Quest Challenge
A competition sponsored by the Space Technology Mission Directorate Centennial Challenge Program, the Cube Quest Challenge awarded a total of $5.5 million to teams that meet the objectives of “designing, building and delivering flight-qualified, small satellites capable of advanced operations near and beyond the moon.” The three winning teams that will have their CubeSats launch on EM-1 are: Cislunar Explorers, CU-E3, and Team Miles.
A pair of spacecraft designed by Cornell University, the Cislunar Explorers is a CubeSat that will test the feasibility of water electrolysis as a means of propulsion. Upon deployment, the two Cislunar Explorers will split apart, head toward the Moon’s atmosphere, and attempt to enter into a lunar orbit. Its fuel for this journey will come from the readily-combustible gaseous mixture of hydrogen and oxygen that result from the bond-breaking decomposition of water via electricity. The Cislunar Explorers will also test the feasibility of optical navigation: using off-the-shelf commercial cameras to observe the sizes of the Earth, the Moon, and the Sun to calculate its own position for navigation. This mission’s success could lead to developments in the use of in-situ space resources, such as collecting water on asteroids, to power spaceflight.
CU Earth Escape Explorer (“CU-E3”)
Developed by University of Colorado at Boulder, the CU-E3 will advance technologies for deep space communications. Via lunar gravity assist and using solar radiation pressure for orientation, CU-E3 will enter into an Earth-trailing heliocentric orbit. While in this orbit, the CU-E3 will gradually draft further and further until it reaches a distance of more than 27 million kilometers away from Earth at the end of its one year mission. During this time, CU-E3’s custom-designed communications systems (which includes an X band transmitter for downlink, a C band transmitter for uplink, and a novel reflectarray antenna and feed horns) will attempt to communicate with the ATLAS Ground Networks on Earth. Through this process, CU-E3 hopes to become the CubeSat that will achieve the following communication objectives: (1) the largest aggregate data volume, (2) the most error-free data blocks, and (3) the most distant communications from Earth.
Team Miles, envisioned by Miles Space, will test plasma thrusters as a form of deep space navigation. The CubeSat will also demonstrate the feasibility of a software-defined radio for communications with earth. Team Miles’ propulsion engine, formally called ConstantQ Thrusters, will use solid iodine as the propellant with thrust being generated through the acceleration of such ions with electricity. The Model H System of the ConstantQ Thrusters will include four canted thruster headers that will enable attitude control and primary propulsion without the need for moving parts. This CubeSat will attempt to travel 96 million kilometers on such propulsion engines before ending its mission.
NASA’s International Partners
NASA’s international partners, including the European Space Agency, via the Italian Space Agency, and Japan Aerospace Exploration Agency (“JAXA”), will also contribute three CubeSats to EM-1: ArgoMoon, EQUULEUS, and OMOTENASHI.
ArgoMoon is being developed by the Italian company Argotec under the supervision of the Italian Space Agency. After the release of the Orion capsule during EM-1’s primary objective phase, the Interim Cryogenic Propulsion Stage (“ICPS”) will no longer be able to send telemetry data back to Earth. Without these data, it will be hard for NASA to monitor, study, and learn from the release of various CubeSats from SLS. ArgoMoon, operating in close proximity to the ICPS, will attempt to fill in this gap by taking and transmitting pictures back to ground control during the CubeSats’ release phase.
Equilibrium Lunar-Earth Point 6U Spacecraft (“EQUULEUS”)
Latin for “little horse,” Equuleus is the name of one of the smallest and faintest of the 88 modern constellations. EQUULEUS is also the name of a CubeSat being jointly-managed by JAXA and University of Tokyo. This mini-satellite will seek to understand the radiation environment around the Earth by imaging Earth’s plasmasphere (via PHOENIX, a UV telescope payload), observing lunar impact flashes by meteors (via DELPHINUS, a camera payload), and measuring the dust environment of the cis-lunar region (via CLOTH, an instrumental payload). EQUULEUS will also test trajectory control of its water-powered propulsion system (ACQUARIUS) in the Sun-Earth-Moon region through a demonstration flight to the Earth-Moon Lagrange point L2.
Outstanding Moon Exploration Technologies demonstrated by Nano Semi-Hard Impactor (“OMOTENASHI”)
A Japanese word that means “welcome” or “hospitality,” OMOTENASHI is also being developed jointly by JAXA and University of Tokyo, and seeks to become the world’s smallest moon lander. Using gas jet thrusters and performing a total of two orbital maneuvers, OMOTENASHI will demonstrate the feasibility of semi-hard landing (about 30 m/s) on the Moon. As a secondary mission, OMOTENASHI will also be equipped with radiation monitors to measure the radiation environment beyond LEO.
Human Exploration and Operations Mission Directorate: https://www.nasa.gov/directorates/heo/index.html
Science Mission Directorate: https://science.nasa.gov/
Cube Quest Challenge: https://www.nasa.gov/directorates/spacetech/centennial_challenges/cubequest/about.htm
LunaH-Map Spacecraft: http://lunahmap.asu.edu/
Lunar Flashlight: https://www.jpl.nasa.gov/cubesat/missions/lunar_flashlight.php
NEA Scout: https://www.nasa.gov/content/nea-scout