EQUULEUS

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EQUULEUS
(EQUilibriUm Lunar-Earth point 6U Spacecraft)
Mission type Technology, science
Mission duration Cruise: 6 months[1]
Science: 6 months
Spacecraft properties
Spacecraft type 6U CubeSat
Manufacturer JAXA and the University of Tokyo
Launch mass 14 kg (31 lb)
Dimensions 10×20×30 cm
Start of mission
Launch date December 2019[2]
Rocket SLS Block 1
Launch site Kennedy LC-39B
Flyby of Moon
Main UV telescope
Name PHOENIX
Diameter 60 mm
Wavelengths extreme ultraviolet: 30.4 nm
Transponders
Band X band and Ka band[1]
TWTA power 13 W[1]
Instruments
PHOENIX
DELPHINUS
CLOTH

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) is a nanosatellite of the 6-Unit CubeSat format that will measure the distribution of plasma that surrounds the Earth (plasmasphere) to help scientists understand the radiation environment in that region.[3] It will also demonstrate low-thrust trajectory control techniques, such as multiple lunar flybys, within the Earth-Moon region using water steam as propellant.[4][1] The spacecraft was designed and developed jointly by the Japan Aerospace Exploration Agency (JAXA) and the University of Tokyo.[4][5]

EQUULEUS will be one of thirteen CubeSats to be carried with the Orion EM-1 mission into a heliocentric orbit in cislunar space on the maiden flight of the Space Launch System, scheduled to launch in December 2019.[6][7]

Overview[edit]

Mapping the plasmasphere around Earth may provide important insight for protecting both humans and electronics from radiation damage during long space journeys. It will also demonstrate low-thrust trajectory control techniques, such as multiple lunar flybys, within the Earth-Moon Lagrangian points (EML).[1][7][8] The mission will demonstrate that departing from EML can transfer to various orbits, such as Earth orbits, Moon orbits, and interplanetary orbits, with a tiny amount of orbital control.[7] EQUULEUS features 2 deployable solar panels, and lithium batteries.

The mission will be monitored from the Japanese deep space antenna (64-meter antenna and 34-meter antenna) with support from the DSN (Deep Space Network) of JPL.[1] The Principal investigator is Professor Hashimoto at the Japan Aerospace Exploration Agency (JAXA).[9] The mission is named after the 'little horse' constellation Equuleus.[10]

Propulsion[edit]

Water thrusters Unit/performance
Propellant Water
Thrust 2 - 4 mN
Specific impulse >70 s
Stored pressure < 100 kPa
Power 12 – 15 W
Water mass 1.2 kg
Total Delta-V 70 m/s

The propulsion system, called AQUARIUS, employs 8 water thrusters also used for attitude control (orientation) and momentum management.[3][11] The spacecraft will carry 1.5 kg of water,[11][12] and the complete propulsion system will occupy about 2.5 units out of the 6 units total spacecraft volume. The waste heat from the communication components is reused to assist in the heating of water vapor, which is heated to 100 °C (212 °F) at the pre-heater.[11] The AQUARIUS' water thrusters produce a total of 4.0 mN, a specific impulse (Isp) of 70 s, and consumes about 20 W power.[11]

Scientific payload[edit]

Several of EQUULEUS's instruments are named after the constellations that neighbor Equuleus.

PHOENIX[edit]

EQUULEUS' scientific payload features a small UV telescope named PHOENIX (Plasmaspheric Helium ion Observation by Enhanced New Imager in eXtreme ultraviolet) that will operate in the high-energy extreme ultraviolet wavelengths. It consists of an entrance mirror of 60 mm diamemeter, and a photon counting device. The reflectivity of the mirror is optimized for the emission line of helium ion (30.4 nm wavelength), which is the relevant component of the Earth's plasmasphere.[13] The plasmasphere is where various phenomena are caused by the electromagnetic disturbances by the solar wind. By flying far from the Earth, the PHOENIX telescope will provide a global image of the Earth's plasmasphere and contribute to its spatial and temporal evolution.[13]

DELPHINUS[edit]

DELPHINUS (DEtection camera for Lunar impact PHenomena IN 6U Spacecraft), or DLP, for short is a camera connected to the PHOENIX telescope to observe lunar impact flashes and near-Earth asteroids, as well as potential 'mini-moons' while positioned at the Earth-Moon Lagrangian point L2 (EML2) halo orbit.[14] Theoretically, NEOs approaching Earth can be briefly caught within Earth's gravity well, and although in terms of orbital mechanics the object's movements is still centered around the sun, to an observer on Earth it will move as if it is a moon of the planet.[15] One example of such an object is 2006 RH120, which orbited Earth between 2006 and 2007. If a mini-moon or NEO that can be rendezvoused by EQUULEUS is identified, the CubeSat will attempt a flyby.[15] This payload occupies about 0.5 units out of the total 6 units volume.[1] The results will contribute to the risk evaluation for future infrastructure or human activity on the lunar surface.[1]

CLOTH[edit]

The instrument named CLOTH (Cis-Lunar Object Detector within Thermal Insulation) will detect and evaluate the meteoroid impact flux in the cislunar space by using dust detectors mounted on the exterior of the spacecraft. The goal of this instrument is to understand the size and spatial distribution of dust solid objects in the cislunar space.[1] CLOTH utilizes the spacecraft's multi-layer insulation (MLI) as a detector, thus realizing a dust counter suitable for mass-constrained CubeSats.[16] It will be the first instrument to measure the dust environment of the Earth–Moon L2 Lagrangian point, and aims to uncover the dust's origin, as well as conducting risk assessment of the L2 point dust particles in anticipation of a future manned mission.[16] CLOTH will decipher L2 point dust (likely originating from mini-moons) from sporadic dust by differences in their impact velocity.[16]

See also[edit]

The 13 CubeSats flying in the Exploration Mission 1
CubeSat and microsatellite projects of ISSL

References[edit]

  1. ^ a b c d e f g h i EQUULEUS: Mission to Earth - Moon Lagrange Point by a 6U Deep Space CubeSat. Utah State University, Small Satellite Conference. 2017.
  2. ^ Clark, Stephen (28 April 2017). "NASA confirms first flight of Space Launch System will slip to 2019". Spaceflight Now. Retrieved 29 April 2017.
  3. ^ a b Moon Lagrange Point by a 6U CubeSat EQUULEUS (PDF). Ryu Funase, Small Satellite Conference. University of Tokyo. 2017.
  4. ^ a b Space Launch System Highlights (PDF). NASA, 16 MAY 2016.
  5. ^ EQUULEUS. Gunter Dirk Krebs, Gunter's Space Page. 2016.
  6. ^ Anderson, Gina; Porter, Molly (8 June 2017). "Three DIY CubeSats Score Rides on NASA's First Flight of Orion, Space Launch System". NASA.
  7. ^ a b c EQUULEUS - Technology Demonstration. Intelligent Space Systems Laboratory, The University of Tokyo. 2017.
  8. ^ International Partners Provide Science Satellites for America’s Space Launch System Maiden Flight. NASA, 26 May 2016.
  9. ^ International Partners Provide Science Satellites for America’s Space Launch System Maiden Flight. NASA News. 26 May 2016.
  10. ^ NASA firms up Space Launch System nanosat manifest. Lester Haines, The Register. 27 May 2016.
  11. ^ a b c d Development of the Water Resistojet Propulsion System for Deep Space Exploration by the CubeSat: EQUULEUS (PDF). Small Satellite Conference. University of Tokyo. 2017.
  12. ^ Development of the Water ResistojetPropulsion System for Deep Space Exploration by the CubeSat EQUULEUS (PDF). Hiroyuki Koizumi, et al Small Satellite Conference. University of Tokyo. 2017.
  13. ^ a b Plasmaspheric Helium ion Observation by Enhanced New Imager in eXtreme ultraviolet. EQUULEUS mission home page. Intelligent Space Systems Laboratory, The University of Tokyo. 2017.
  14. ^ DELPHINUS. Intelligent Space Systems Laboratory, The University of Tokyo. 2017.
  15. ^ a b "DELPHINUS". Intelligent Space Systems Laboratory. Retrieved 2017-11-26.
  16. ^ a b c Yano, Hajime; Hirai, Takayuki; Arai, Kazuyoshi (5 January 2017). "EQUULEUS搭載地球・月軌道間微粒子検出機能断熱材(CLOTH)の開発" (PDF) (in Japanese). JAXA. Retrieved 2017-04-27.