View source for AMPTE-UKS

{{Short description|United Kingdom satellite of the Explorer program}}
{{Use American English|date=November 2021}}
{{Use dmy dates|date=November 2021}}
{{Infobox spaceflight
| name              = AMPTE-UKS
| names_list        = AMPTE-United Kingdom Subsatellite
| image             =
| image_caption     =
| image_size        = 300px
| mission_type      = [[Magnetosphere|Magnetosphere research]]
| operator          = [[NASA]] / [[United Kingdom]]
| COSPAR_ID         = 1984-088C
| SATCAT            = 15201
| mission_duration  = 5 months (achieved)
| spacecraft        = AMPTE-UKS
| spacecraft_type   = Active Magnetospheric Particle Tracer Explorers (AMPTE)
| spacecraft_bus    = AMPTE-United Kingdom Subsatellite
| manufacturer      = [[Rutherford Appleton Laboratory]]
| launch_mass       = {{cvt|77|kg}}
| dimensions        =
| power             =
| launch_date       = 16 August 1984, 14:48 [[Coordinated Universal Time|UTC]]<ref name="JSR"/>
| launch_rocket     = [[Delta 3000|Delta 3924]] (Delta 175)
| launch_site       = [[Cape Canaveral Space Force Station|Cape Canaveral]], [[Cape Canaveral Launch Complex 17|LC-17A]]
| launch_contractor = [[Douglas Aircraft Company]]
| entered_service   = 16 August 1984
| last_contact      = 15 January 1985
| deactivated       =
| decay_date        =
| orbit_reference   = [[Geocentric orbit]]<ref name="Trajectory"/>
| orbit_regime      = [[Highly elliptical orbit]]
| orbit_periapsis   = {{cvt|550|km}}
| orbit_apoapsis    = {{cvt|112800|km}}
| orbit_inclination = 28.50°
| orbit_period      = 2630.00 minutes
| apsis             = gee
| instruments       = 3-D Electron Analyzer (6 eV-25 keV, 8-Sector, 5-seconds Averaged)<br/>3-D Ion Analyzer (10 eV-20 keV/Q, 12-Sector, 5-seconds Averaged)<br/>Particle Modulation Analyzer (1 Hz-1 MHz Fast Fourier Transform)<br/>Plasma Wave Spectrometer (100 Hz-3 MHz E, 100 Hz-60 kHz B)<br/>Triaxial Magnetometer (Dual Range 0.03 nT Accuracy)
| programme         = '''[[Explorers Program|Explorer program]]'''
| previous_mission  = [[AMPTE-IRM]]
| next_mission      = [[Cosmic Background Explorer]] (Explorer 66)
}}
'''AMPTE-UKS''', also called '''AMPTE-United Kingdom Subsatellite''', was a [[United Kingdom]] satellite designed and tasked to study the [[Magnetosphere|magnetosphere of Earth]], being launched as part of the [[Explorers Program|Explorer program]]. The AMPTE (Active Magnetospheric Particle Tracer Explorers) mission was designed to study the access of [[solar wind]] [[ion]]s to the magnetosphere, the convective-diffusive transport and energization of magnetospheric particles, and the interactions of [[Plasma (physics)|plasmas]] in space.<ref name="Display"/>
== Mission ==
The AMPTE-UKS is one of the three components of the international space mission AMPTE, which also included '''[[AMPTE-CCE]]''' (Charge Compositio9n Explorer), designed by [[NASA]], and '''[[AMPTE-IRM]]''' (Ion Release Module), provided by [[Germany]].<ref name="Display"/>
== Spacecraft ==
The program consisted of three spacecraft: the AMPTE-CCE, which measured, in the magnetosphere, the ions released by the AMPTE-IRM; the AMPTE-IRM, which provided multiple ion releases in the solar wind, the [[magnetosheath]], and the [[Magnetosphere|magnetotail]], with [[in situ]] diagnostics of each; and the AMPTE-UKS. The AMPTE-UKS was one spacecraft of the AMPTE program (along with AMPTE-CCE and AMPTE-IRM) and served as a [[subsatellite]] of the AMPTE-IRM spacecraft. Its purpose was to help distinguish between spatial structure and temporal changes in the plasma phenomena initiated by ion releases from the AMPTE-IRM and in the natural magnetospheric environment. Measured quantitie were similar to those of the AMPTE-IRM and include [[magnetic field]]s, [[Ion|positive ion]]s, [[electron]]s, [[Waves in plasmas|plasma wave]]s, and modulations in ions and electrons. The spacecraft was [[Spin-stabilisation|spin-stabilized]] at 12 [[Revolutions per minute|rpm]] and employed [[S band|S-band]] communications. It carried a cold gas propulsion system and a [[very high frequency]] (VHF) radar system for station keeping with the AMPTE-IRM normally at a distance of a few hundred kilometers.<ref name="Display"/>
== Launch ==
AMPTE-UKS was launched with the two other satellites of the '''AMPTE''' program on 16 August 1984, at 16:48 [[Coordinated Universal Time|UTC]], from a [[Cape Canaveral Space Force Station|Cape Canaveral]] launch pad by a [[Delta 3000|Delta 3924]] [[launch vehicle]].<ref name="JSR">{{cite web |url=http://www.planet4589.org/space/log/launchlog.txt |title=Launch Log |publisher=Jonathan's Space Report |date=21 July 2021 |access-date=26 November 2021}}</ref><ref name="Trajectory"/>
== Experiments ==
=== 3-D Electron Analyzer (6 eV-25 keV, 8-Sector, 5-seconds Averaged) ===
Electron distribution functions were measured using two hemispherical electrostatic analyzers with microchannel plate detectors. The instrument had several operating modes. In its primary mode, electron intensities were measured, in 1-second periods, in 24 energy channels covering the range 6 eV to 25 keV within 8 angular sectors spanning 180° relative to the spacecraft spin axis. Data from a complete 5-second UKS spin period were needed to measure the three-dimensional distribution function. The geometric factors of the sectors were within the range 0.4 to {{cvt|1.0|mm2}}-sr and the energy bandwidth, delta E/E, was 3%.<ref name="Experiment2">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1984-088C-02 |title=Experiment: 3-D Electron Analyzer (6 eV-25 keV, 8-Sector, 5-seconds Averaged) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
=== 3-D Ion Analyzer (10 eV-20 keV/Q, 12-Sector, 5-seconds Averaged) ===
The objective of this investigation was to study the three-dimensional ion distributions in the plasma clouds, the solar wind, the magnetosphere, and the boundaries between them and to measure these distributions with high time and angular resolutions. The instrument consisted of a pair of 270° spherical electrostatic energy analyzers with microchannel plate detectors that measured the three-dimensional energy/charge distribution of positive ions from 10 [[Electronvolt|eV]]/Q to 20 keV/Q over the polar angle range 0 to 180° with respect to the spin axis of the spacecraft. A complete set of measurements was obtained every 5-second spin period.<ref name="Experiment3">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1984-088C-03 |title=Experiment: 3-D Ion Analyzer (10 eV-20 keV/Q, 12-Sector, 5-seconds Averaged) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
=== Particle Modulation Analyzer (1 Hz-1&nbsp;MHz Fast Fourier Transform) ===
The instrument consisted of microprocessor-controlled counting and timing circuitry which used as input the particle arrival pulses from the electron and ion spectrometers on board the spacecraft. The instrument computed autocorrelation functions and [[Fast Fourier transform]]s of the particle modulations resulting from wave-particle interactions in the frequency range 1 Hz to 1 MHz with an average frequency resolution of 3%.<ref name="Experiment1">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1984-088C-01 |title=Experiment: Particle Modulation Analyzer (1 Hz-1 MHz Fast Fourier Transform) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
=== Plasma Wave Spectrometer (100 Hz-3&nbsp;MHz E, 100 Hz-60&nbsp;kHz B) ===
The instrument consisted of an electric dipole antenna with {{cvt|7|m}} separation between its sensors and a high permeability core coil to measure the magnetic component of the wave field. The electric component was measured up to 2 MHz and the magnetic component up to kHz. The signal processing equipment was composed of a stepped-frequency analyzer covering the range up to 130 kHz and four discrete filters with 10% bandwidths covering the range up to 2 MHz. A correlator (64 point auto) permitted study at higher frequency resolution.<ref name="Experiment5">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1984-088C-05 |title=Experiment: Plasma Wave Spectrometer (100 Hz-3 MHz E, 100 Hz-60 KHz B) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
=== Triaxial Magnetometer (Dual Range 0.03 nT Accuracy) ===
The objective of this investigation was to study the magnetic fields in the near-Earth environment. The instrument consisted of a three-axis orthogonal fluxgate magnetometer with ring-core sensors. It was a refurbished [[ISEE-1]] and [[International Cometary Explorer|ISEE-3]] flight spare. One of the two possible ranges, ± 256 or 8192 [[Tesla (unit)|nT]], could be selected by ground command. The accuracy of the instrument was ± 1 nT per axis in the high range and ± 0.03 nT in the low range.<ref name="Experiment4">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1984-088C-04 |title=Experiment: Triaxial Magnetometer (Dual Range 0.03 nT Accuracy) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
== End of mission ==
The spacecraft power supply failed on 15 January 1985.<ref name="Display">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-088C |title=Display: AMPTE-UKS (1984-088C) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref><ref name="Trajectory">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1984-088C |title=Trajectory: AMPTE-UKS (1984-088C) |publisher=NASA |date=28 October 2021 |access-date=26 November 2021}} {{PD-notice}}</ref>
== See also ==
{{Portal|Spaceflight}}
* [[AMPTE-CCE]]
* [[AMPTE-IRM]]
* [[Explorers Program|Explorer program]]
== References ==
{{Reflist|30em}}
== External links ==
* [http://sd-www.jhuapl.edu/AMPTE/ JHUAPL AMPTE]
{{Explorer program}}
{{Orbital launches in 1984}}
[[Category:1984 in spaceflight]]
[[Category:Explorers Program]]
[[Category:Spacecraft launched in 1984]]
[[Category:Spacecraft launched by Delta rockets]]
[[Category:Satellites orbiting Earth]]