THEMIS

Last updated

THEMIS
Five Themis satellites seen from above.jpg
Five THEMIS satellites
Names
  • Explorer 85 - THEMIS-A - THEMIS-P5 - MIDEX-5A
    * Explorer 86 - THEMIS-B (ARTEMIS-P1) - THEMIS-P1 - MIDEX-5B
    * Explorer 87 - THEMIS-C (ARTEMIS-P2) - THEMIS-P2 - MIDEX-5C
    * Explorer 88 - THEMIS-D - THEMIS-P3 - MIDEX-5D
    * Explorer 89 - THEMIS-E - THEMIS-P4 - MIDEX-5E
Mission type Magnetospheric research
Operator NASA
COSPAR ID 2007-004 (A, B, C, D, E)
SATCAT no. 30580, 30581, 30582, 30583, 30584
Website http://themis.igpp.ucla.edu/
Mission durationPlanned: 2 years
Elapsed: 17 years, 5 months and 6 days
Spacecraft properties
SpacecraftExplorer LXXXV
Spacecraft typeTime History of Events and Macroscale Interactions during Substorms
Bus THEMIS
Manufacturer Swales Aerospace
Launch mass126 kg (each) [1]
Power37 watts (each)
Start of mission
Launch date17 February 2007, 23:01:00 UTC
Rocket Delta II 7925-10C (Delta 323)
Launch site Cape Canaveral, SLC-17B
Contractor Boeing Defense, Space & Security
Entered service4 December 2007
Orbital parameters
Reference system Geocentric orbit [2]
Regime Highly Elliptical Orbit
Perigee altitude 470 km (290 mi)
Apogee altitude 87,330 km (54,260 mi)
Inclination 16.00°
Period 1870.00 minutes
Instruments
Electric Field Instruments (EFI)
Electrostatic Analyzer (ESA)
Fluxgate magnetometer (FGM)
Search-coil magnetometer (SCM)
Solid State Telescope (SST)
THEMIS logo.png
THEMIS mission patch
Explorer program
  Neil Gehrels Swift Observatory (Explorer 84)
AIM (Explorer 90) 
 

Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission began in February 2007 as a constellation of five NASA satellites (THEMIS-A through THEMIS-E) to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan Themis. [3]

Contents

Three of the satellites orbit the Earth within the magnetosphere, while two have been moved into orbit around the Moon. Those two were renamed ARTEMIS for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun. THEMIS-B became ARTEMIS-P1 and THEMIS-C became ARTEMIS-P2. [4] ARTEMIS-P1 and -P2 together comprise the THEMIS-ARTEMIS mission. [5]

The THEMIS satellites were launched 17 February 2007 from SLC-17B aboard a Delta II launch vehicle. [3] [6] Each satellite carries five identical instruments, including a fluxgate magnetometer (FGM), an electrostatic analyzer (ESA), a solid state telescope (SST), a search-coil magnetometer (SCM) and an electric field instrument (EFI). Each probe has a mass of 126 kg (278 lb), including 49 kg (108 lb) of hydrazine fuel. [7]

THEMIS data can be accessed using the SPEDAS software. Canada, Austria, Germany, and France also contributed to the mission.

Spacecraft

Swales Aerospace, now part of Orbital ATK which is now part of Northrop Grumman, Beltsville, Maryland, manufactured all five probes for this mission. Each was built-up and tested at the Beltsville facility, before being delivered to University of California, Berkeley for instrument integration. Swales was responsible for integrating the BAU, IRU, Solar arrays, antenna, battery, and other components necessary for functionality. This was the second major satellite built by Swales, the first being the Earth Observing-1 (EO-1) spacecraft, which continues to orbit Earth. Swales was also responsible for designing and building the Electrical Ground Support Equipment (EGSE) used for monitoring the probes during all phases of pre-launch activities, including use at the launch site.

Testing

After the installation of instruments at SSL, Berkeley, pre-launch testing including thermal-vacuum, vibration and acoustic tests, was conducted at NASA's Jet Propulsion Laboratory in Pasadena, California.

Launch

The launch of THEMIS atop the Delta II 7925-10C launch vehicle, at SLC-17B, Cape Canaveral Clouds of smoke around the 323rd Delta rocket on launch pad 17B.jpg
The launch of THEMIS atop the Delta II 7925-10C launch vehicle, at SLC-17B, Cape Canaveral

THEMIS was originally scheduled to launch on 19 October 2006. Owing to delays caused by workmanship problems with Delta II second stages — an issue that also affected the previous mission, STEREO — the THEMIS launch was delayed to 15 February 2007. Due to weather conditions occurring on 13 February 2007, fueling of the second stage was delayed, and the launch pushed back 24 hours. On 16 February 2007, the launch was scrubbed in a hold at the T-4 minute point in the countdown due to the final weather balloon reporting a red, or no-go condition for upper-level winds. A 24-hour turnaround procedure was initiated, targeting a new launch window between 23:01 and 23:17 UTC on 17 February 2007.

Favorable weather conditions were observed on 17 February 2007, and the countdown proceeded smoothly. THEMIS successfully launched at 23:01:00 UTC. The spacecraft separated from the launch vehicle approximately 73 minutes after liftoff. By 03:07 UTC, on 18 February, mission operators at the Space Sciences Laboratory (SSL) of the University of California, Berkeley, commanded and received signals from all five spacecraft, confirming nominal separation status.

The launch service was provided by the United Launch Alliance through the NASA Launch Services Program (LSP).

FAST

The Fast Auroral SnapshoT Explorer (FAST) mission supported THEMIS in 2008 and 2009 before being retired. [8] FAST was a Small Explorer program (SMEX) mission launched in 1996. [8]

Mission status

From 15 February 2007 until 15 September 2007, the five THEMIS satellites coasted in a string-of-pearls orbital configuration. From 15 September until 4 December 2007, the satellites were moved to more distant orbits in preparation for data collection in the magnetotail. This phase of the mission was called the "Dawn Phase" because the satellites' orbits were in apogee on the dawn side of the magnetosphere. On 4 December 2007, the first tail science phase of the mission began. In this segment of the mission scientists will collect data from the magnetotail of the Earth's magnetosphere. During this phase the satellites' orbits are in apogee inside the magnetotail. The scientists hope to observe substorms and magnetic reconnection events. During these events charged particles stored in the Earth's magnetosphere are discharged to form the aurora borealis. Tail science is performed in the winter of the northern hemisphere because the ground magnetometers that Themis scientists correlate the satellite data with have relatively longer periods of night. During the night, observations are not interrupted by charged particles from the Sun. [9]

In 2007, THEMIS "found evidence of magnetic ropes connecting Earth's upper atmosphere directly to the Sun", reconfirming the theory of solar-terrestrial electrical interaction (via "Birkeland currents" or "field-aligned currents") proposed by Kristian Birkeland circa 1908. [10] [11] NASA also likened the interaction to a "30 kiloVolt battery in space", noting the "flux rope pumps 650,000 Ampere current into the Arctic!" [12]

On 26 February 2008, THEMIS probes were able to determine, for the first time, the triggering event for the onset of magnetospheric substorms. [13] Two of the five probes, positioned approximately one third the distance to the Moon, measured events suggesting a magnetic reconnection event 96 seconds prior to Auroral intensification. [14] Vassilis Angelopoulos of the University of California, Los Angeles, who is the principal investigator for the THEMIS mission, claimed, "Our data show clearly and for the first time that magnetic reconnection is the trigger". [15]

Extended mission

On 19 May 2008, the Space Sciences Laboratory (SSL) at University of California, Berkeley announced NASA had extended the THEMIS mission to the year 2012. NASA officially approved the movement of THEMIS-B and THEMIS-C into lunar orbit under the mission name "ARTEMIS" (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun), which was revised to "THEMIS-ARTEMIS" in 2019. [5] In February 2017, THEMIS celebrated ten years of science operations. As of August 2017, the three THEMIS inner probes continue to collect valuable data on the Sun's interaction with the Earth's magnetosphere.

ARTEMIS

ARTEMIS probes in lunar orbit ARTEMIS mission.jpg
ARTEMIS probes in lunar orbit

In early 2010, ARTEMIS-P1 (THEMIS-B) performed two lunar flybys and one Earth flyby, and approached insertion into a Lissajous orbit around a lunar Lagrange point. Lunar orbit insertion was targeted for April 2011. ARTEMIS-P2 (THEMIS-C) completed a lunar flyby and was on the inbound leg of the first of three deep space excursions on its way to a Lissajous orbit and was targeted for lunar orbit in April 2011. [16]

On 22 June 2011, ARTEMIS-P1 began firing its thrusters to move out of its kidney-shaped libration orbit on one side of the Moon, where it had been since January 2011. [17] On 2 July 2011 at 16:30 UTC, ARTEMIS-P1 entered lunar orbit. The second spacecraft, ARTEMIS-P2, moved into lunar orbit on 17 July 2011. [18] Along the way, the two spacecraft were the first to achieve orbit around the Moon's Lagrange points. [17] [19]

As of October 2019, both lunar probes are in stable orbits, and are expected to remain operational for a long time. [5]

Animation of THEMIS-B
Animation of THEMIS-B trajectory - Geocentric orbit.gif
Geocentric orbit phase
Animation of THEMIS-B trajectory - Trans-lunar injection.gif
Trans-lunar injection phase
Animation of THEMIS-B trajectory - Lissajous orbit.gif
Lissajous orbit phase
Animation of THEMIS-B trajectory - Selenocentric orbit.gif
Selenocentric orbit phase
  THEMIS-B ·   Earth  ·   Moon

Instruments

Aboard the spacecraft

Ground based

As the satellites monitor the magnetosphere from orbit, twenty ground stations in North America simultaneously monitor auroras. Ground station mission and science operations are being managed by the University of California's Space Sciences Laboratory.

Research results

The THEMIS instruments have been used to track whistler-mode chorus waves during can persist in periods of low geomagnetic activity. [21] [22]

Lists of relevant topics

Other relevant spacecraft

See also

Related Research Articles

<i>Nozomi</i> (spacecraft) Failed Mars orbiter

Nozomi was a Japanese Mars orbiter that failed to reach Mars due to electrical failure. It was constructed by the Institute of Space and Astronautical Science, University of Tokyo and launched on July 4, 1998, at 03:12 JST with an on-orbit dry mass of 258 kg and 282 kg of propellant. The Nozomi mission was terminated on December 31, 2003.

<i>MESSENGER</i> NASA mission to Mercury

MESSENGER was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geochemistry, and Ranging", and a reference to the messenger god Mercury from Roman mythology.

<span class="mw-page-title-main">Cluster II (spacecraft)</span> European Space Agency mission

Cluster II is a space mission of the European Space Agency, with NASA participation, to study the Earth's magnetosphere over the course of nearly two solar cycles. The mission is composed of four identical spacecraft flying in a tetrahedral formation. As a replacement for the original Cluster spacecraft which were lost in a launch failure in 1996, the four Cluster II spacecraft were successfully launched in pairs in July and August 2000 onboard two Soyuz-Fregat rockets from Baikonur, Kazakhstan. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. In February 2021, Cluster II celebrated 20 years of successful scientific operations in space. As of March 2023, its mission has been extended until September 2024. The China National Space Administration/ESA Double Star mission operated alongside Cluster II from 2004 to 2007.

<i>Wind</i> (spacecraft) NASA probe to study solar wind, at L1 since 1995

The Global Geospace Science (GGS) Wind satellite is a NASA science spacecraft designed to study radio waves and plasma that occur in the solar wind and in the Earth's magnetosphere. It was launched on 1 November 1994, at 09:31:00 UTC, from launch pad LC-17B at Cape Canaveral Air Force Station (CCAFS) in Merritt Island, Florida, aboard a McDonnell Douglas Delta II 7925-10 rocket. Wind was designed and manufactured by Martin Marietta Astro Space Division in East Windsor Township, New Jersey. The satellite is a spin-stabilized cylindrical satellite with a diameter of 2.4 m and a height of 1.8 m.

<span class="mw-page-title-main">Ørsted (satellite)</span> Satellite

Ørsted is an Earth science satellite launched in 1999 to study the Earth's geomagnetic field. It is Denmark's first satellite, named after Hans Christian Ørsted (1777–1851), a Danish physicist and professor at the University of Copenhagen, who discovered electromagnetism in 1820.

<span class="mw-page-title-main">Geotail</span> NASA/ISAS spacecraft

Geotail was a satellite that observed the Earth's magnetosphere. It was developed by Japan's ISAS in association with the United States' NASA, and was launched by a Delta II rocket on 24 July 1992 from Cape Canaveral Air Force Station.

<span class="mw-page-title-main">Magnetosphere of Jupiter</span> Cavity created in the solar wind

The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.

<span class="mw-page-title-main">Canadian Geospace Monitoring</span>

Canadian Geospace Monitoring (CGSM) is a Canadian space science program that was initiated in 2005. CGSM is funded primarily by the Canadian Space Agency, and consists of networks of imagers, meridian scanning photometers, riometers, magnetometers, digital ionosondes, and High Frequency SuperDARN radars. The overarching objective of CGSM is to provide synoptic observations of the spatio-temporal evolution of the ionospheric thermodynamics and electrodynamics at auroral and polar latitudes over a large region of Canada.

<i>Polar</i> (satellite) NASA science spacecraft which studied the polar magnetosphere until 2008

The Global Geospace Science (GGS) Polar satellite was a NASA science spacecraft designed to study the polar magnetosphere and aurorae. It was launched into orbit in February 1996, and continued operations until the program was terminated in April 2008. The spacecraft remains in orbit, though it is now inactive. Polar is the sister ship to GGS Wind.

<span class="mw-page-title-main">Magnetospheric Multiscale Mission</span> Four NASA robots studying Earths magnetosphere (2015-present)

The Magnetospheric Multiscale (MMS) Mission is a NASA robotic space mission to study the Earth's magnetosphere, using four identical spacecraft flying in a tetrahedral formation. The spacecraft were launched on 13 March 2015 at 02:44 UTC. The mission is designed to gather information about the microphysics of magnetic reconnection, energetic particle acceleration, and turbulence⁠ — processes that occur in many astrophysical plasmas. As of March 2020, the MMS spacecraft has enough fuel to remain operational until 2040.

<span class="mw-page-title-main">Spacecraft magnetometer</span> Widely used scientific instrument aboard satellites and probes

Spacecraft magnetometers are magnetometers used aboard spacecraft and satellites, mostly for scientific investigations, plus attitude sensing. Magnetometers are among the most widely used scientific instruments in exploratory and observation satellites. These instruments were instrumental in mapping the Van Allen radiation belts around Earth after its discovery by Explorer 1, and have detailed the magnetic fields of the Earth, Moon, Sun, Mars, Venus and other planets and moons. There are ongoing missions using magnetometers, including attempts to define the shape and activity of Saturn's core.

<span class="mw-page-title-main">Substorm</span> Short term magnetosphere disturbance

A substorm, sometimes referred to as a magnetospheric substorm or an auroral substorm, is a brief disturbance in the Earth's magnetosphere that causes energy to be released from the "tail" of the magnetosphere and injected into the high latitude ionosphere. Visually, a substorm is seen as a sudden brightening and increased movement of auroral arcs. Substorms were first described in qualitative terms by Kristian Birkeland which he called polar elementary storms. Sydney Chapman used the term substorm about 1960 which is now the standard term. The morphology of aurora during a substorm was first described by Syun-Ichi Akasofu in 1964 using data collected during the International Geophysical Year.

<span class="mw-page-title-main">Heliophysics Science Division</span>

The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended Solar System environment, and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere.

<span class="mw-page-title-main">ISEE-2</span>

The ISEE-2 was an Explorer-class daughter spacecraft, International Sun-Earth Explorer-2, was part of the mother/daughter/heliocentric mission. ISEE-2 was a 165.78 kg (365.5 lb) space probe used to study magnetic fields near the Earth. ISEE-2 was a spin-stabilized spacecraft and based on the design of the prior IMP series of spacecraft. ISEE-1 and ISEE-2 were launched on 22 October 1977, and they re-entered on 26 September 1987.

<span class="mw-page-title-main">SMILE (spacecraft)</span> Chinese–European satellite studying Earths magnetosphere

Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a planned joint venture mission between the European Space Agency and the Chinese Academy of Sciences. SMILE will image for the first time the magnetosphere of the Sun in soft X-rays and UV during up to 40 hours per orbit, improving our understanding of the dynamic interaction between the solar wind and Earth's magnetosphere. The prime science questions of the SMILE mission are

Magnetometer (<i>Juno</i>) Scientific instrument on the Juno space probe

Magnetometer (MAG) is an instrument suite on the Juno orbiter for planet Jupiter. The MAG instrument includes both the Fluxgate Magnetometer (FGM) and Advanced Stellar Compass (ASC) instruments. There two sets of MAG instrument suites, and they are both positioned on the far end of three solar panel array booms. Each MAG instrument suite observes the same swath of Jupiter, and by having two sets of instruments, determining what signal is from the planet and what is from spacecraft is supported. Avoiding signals from the spacecraft is another reason MAG is placed at the end of the solar panel boom, about 10 m and 12 m away from the central body of the Juno spacecraft.

Waves (<i>Juno</i>) Experiment on the Juno spacecraft to study radio and plasma waves

Waves is an experiment on the Juno spacecraft for studying radio and plasma waves. It is part of a collection of various types of instruments and experiments on the spacecraft; Waves is oriented towards understanding fields and particles in the Jupiter's magnetosphere. Waves is on board the uncrewed Juno spacecraft, which was launched in 2011 and arrived at Jupiter in the summer of 2016. The major focus of study for Waves is Jupiter's magnetosphere, which if could be seen from Earth would be about twice the size of a full moon. The magnetosphere has a tear drop shape, and that tail extends away from the Sun by at least 5 AU. The Waves instrument is designed to help understand the interaction between Jupiter's atmosphere, its magnetic field, its magnetosphere, and to understand Jupiter's auroras. It is designed to detect radio frequencies from 50 Hz up to 40,000,000 Hz (40 MHz), and magnetic fields from 50 Hz to 20,000 Hz (20 kHz). It has two main sensors: a dipole antenna and a magnetic search coil. The dipole antenna has two whip antennas that extend 2.8 meters and are attached to the main body of the spacecraft. This sensor has been compared to a rabbit-ear TV antenna. The search coil is overall a Mu-metal rod 15 cm (6 in) in length with a fine copper wire wound 10,000 times around it. There are also two frequency receivers that each cover certain bands. Data handling is done by two radiation-hardened systems on a chip. The data handling units are located inside the Juno Radiation Vault. Waves is allocated 410 Mbits of data per science orbit.

Rumi Nakamura is an Earth scientist at the Austrian Academy of Sciences. She works on solar-terrestrial interactions, with a particular focus on the terrestrial magnetosphere. Nakamura won the 2014 European Geosciences Union Julius Bartels Medal.

<span class="mw-page-title-main">Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites</span> Planned NASA heliophysics spacecraft

Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) is a planned orbiter mission tasked to study the origins of the solar wind and how it affects Earth. TRACERS was proposed by Craig A. Kletzing at the University of Iowa who served as Principal Investigator until his death in 2023. David M. Miles at the University of Iowa was named as Principal Investigator in his stead. The TRACERS mission received US$115 million in funding from NASA.

The Solar-Terrestrial Observer for the Response of the Magnetosphere (STORM) was one of five mission proposals selected to proceed to Phase A concept studies as part of the 2019 NASA Heliophysics Medium Class Explorer Announcement of Opportunity. STORM will provide the first-ever global view of the Sun-Earth system. STORM takes simultaneous observations of the solar wind and the response of Earth’s magnetosphere, including the magnetopause, auroral oval, and ring current dynamics, using global multi-spectral and neutral atom imaging to quantify the global circulation of the energy that powers space weather.

References

  1. "ARTEMIS (THEMIS)". NASA's Solar System Exploration website. Retrieved 29 November 2022.
  2. "Trajectory: THEMIS-A (Explorer 85) 2007-004A". NASA. 28 October 2021. Retrieved 5 December 2021.PD-icon.svg This article incorporates text from this source, which is in the public domain.
  3. 1 2 "THEMIS (Explorer 85)". NASA. 28 October 2021. Retrieved 4 December 2021.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  4. Phillips, Tony. "Dead Spacecraft Walking". ARTEMIS mission site. NASA. Archived from the original on 18 September 2011. Retrieved 28 June 2011.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  5. 1 2 3 Johnson-Groh, Mara (7 October 2019). "Artemis, meet ARTEMIS: Pursuing Sun Science at the Moon". NASA. Retrieved 10 October 2019.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  6. Justin Ray (18 February 2007). "Mission Status Center: THEMIS". SpaceFlight Now. Retrieved 2 December 2009.
  7. "SPACEWARN Bulletin, No. 640". NASA. 1 March 2007. Retrieved 2 December 2009.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  8. 1 2 FAST EPO News
  9. Space Sciences Laboratory (2009). "Themis Orbits". UC Berkeley. Retrieved 2 December 2009.
  10. Cynthia O'Carroll (11 December 2007). "NASA Spacecraft Make New Discoveries About Northern Lights". Goddard Space Flight Center. Archived from the original on 28 June 2022. Retrieved 2 December 2009.
  11. Tony Phillips (20 March 2008). "Spring is Aurora Season". NASA. Archived from the original on 25 September 2009. Retrieved 2 December 2009.
  12. Cynthia O'Carroll (7 December 2007). "Multimedia for the Press Event for THEMIS". Goddard Space Flight Center. Archived from the original on 1 October 2008. Retrieved 2 December 2009.
  13. Laura Layton (24 July 2008). "THEMIS Satellites Discover What Triggers Eruptions of the Northern Lights". NASA. Retrieved 2 December 2009.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  14. Vassilis Angelopoulos; et al. (15 August 2008). "Tail Reconnection Triggering Substorm Onset". Science. 321 (5891): 931–935. Bibcode:2008Sci...321..931A. doi: 10.1126/science.1160495 . PMID   18653845. S2CID   206514133.
  15. Tariq Malik (24 July 2008). "Secret of Colorful Auroras Revealed". Space.com. Retrieved 2 December 2009.
  16. Space Sciences Laboratory. "THEMIS News and Events". UC Berkeley. Archived from the original on 22 June 2010. Retrieved 9 April 2010.
  17. 1 2 Fox, Karen C. (25 March 2015). "First ARTEMIS Spacecraft Successfully Enters Lunar Orbit". The Sun-Earth Connection: Heliophysics. NASA.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  18. Hendrix, Susan (25 March 2015). "Second ARTEMIS Spacecraft Successfully Enters Lunar Orbit". The Sun-Earth Connection: Heliophysics. NASA. Archived from the original on 3 February 2023. Retrieved 21 July 2011.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  19. Broschart, S. B. (2009). Preliminary Trajectory Design for the ARTEMIS Lunar Mission (PDF). AAS/AIAA Astrodynamics Specialists Meeting. 09-382. Pittsburg.
  20. 1 2 "THEMIS - eoPortal Directory - Satellite Missions". earth.esa.int. Retrieved 12 January 2022.
  21. Li, Wen; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.; Cully, C. M.; Ni, B.; LeContel, O.; Roux, A.; Auster, U.; Magnes, W. (7 May 2009). "Global distribution of whistler-mode chorus waves observed on the THEMIS spacecraft". Geophysical Research Letters. 36 (9): L09104. Bibcode:2009GeoRL..36.9104L. doi: 10.1029/2009GL037595 . S2CID   120391902.
  22. Li, Wen; Bortnik, J.; Thorne, R. M.; Angelopoulos, V. (2011). "Global distribution of wave amplitudes and wave normal angles of chorus waves using THEMIS wave observations". Journal of Geophysical Research: Space Physics. 116 (A12). Bibcode:2011JGRA..11612205L. doi: 10.1029/2011JA017035 . ISSN   2156-2202.