Aeronomy of Ice in the Mesosphere

The Aeronomy of Ice in the Mesosphere (AIM) is a satellite originally launched to conduct a 26-month study of noctilucent clouds (NLCs). Its mission was extended, and as of 2019 is still operational.[3] It is the ninetieth Explorer program mission and is part of the NASA-funded Small Explorer program (SMEX). On April 25, 2007 AIM was boosted into a 600 km (370 mi) high polar orbit by a Pegasus-XL rocket, which was air-launched from the Lockheed L-1011 Stargazer aircraft operated by Orbital Sciences.[4]

AIM
Mission typeAtmospheric research
OperatorNASA
COSPAR ID2007-015A
SATCAT no.31304
Websiteaim.hamptonu.edu
Mission durationElapsed: 13 years, 1 month, 29 days
Spacecraft properties
BusLEOStar-2
Launch mass197 kilograms (434 lb)[1]
Start of mission
Launch date25 April 2007, 20:26:03 (2007-04-25UTC20:26:03Z) UTC
RocketPegasus-XL F38
Launch siteStargazer, Vandenberg Runway 12/30
ContractorOrbital Sciences
Orbital parameters
Reference systemGeocentric
RegimeSun-synchronous
Semi-major axis6,926.82 kilometers (4,304.13 mi)[2]
Eccentricity0.0005254[2]
Perigee altitude552 kilometers (343 mi)[2]
Apogee altitude559 kilometers (347 mi)[2]
Inclination97.90 degrees[2]
Period95.63 minutes[2]
RAAN159.47 degrees[2]
Argument of perigee213.55 degrees[2]
Mean anomaly15.06 degrees[2]
Mean motion15.06[2]
Epoch25 January 2015, 00:23:24 UTC[2]
Revolution no.42,300[2]
 

Spacecraft and instruments

The AIM satellite is a 200 kg (440 lb), 1.4 m (4 ft 7 in) by 1.1 m (3 ft 7 in) spacecraft, powered by two solar arrays, carrying three instruments:[5]

Illustration Instrument Name Abbr. Description and scientific objective
Cloud Imaging and Particle Size
CIPS
 The instrument has four cameras positioned at different angles, which provide multiple views of the clouds from different angles and will allow a determination of the sizes of the ice particles that make up the cloud.
The Cosmic Dust Experiment
[6]
CDE
 The instrument records impacts from cosmic dust particles as they enter Earth's upper atmosphere. The instrument uses fourteen polyvinylidene fluoride detectors, which emit a pulse of charge when impacted by a hypervelocity dust particle (velocity 1 km/s (0.62 mi/s)). A measurement of the value and variability of the cosmic dust input will allow scientists to determine the role the particles have in PMC (Polar Mesospheric Cloud) formation. CDE is a nearly identical replica to the Student Dust Counter on the New Horizons mission.[6]
The Solar Occultation for Ice Experiment
[7]
SOFIE
 The SOFIE experiment use solar occultation to measure cloud particles, temperature and atmospheric gases involved in forming the clouds. The instrument will reveal the mixture of chemicals that prompt NLC's formation, as well as the environment in which the clouds form.[7]

Noctilucent clouds

The noctilucent clouds AIM is to study, also known as Polar mesospheric clouds, occur in the Earth's atmosphere at high altitudes of roughly 80 kilometers (50 mi) above the surface, far higher than other clouds. The AIM mission will help determine what factors — temperature, water vapor, and dust particles — lead to the formation of these clouds. The clouds seem to be a relatively recent phenomenon: they were first seen in 1885, and lately seem to be occurring more frequently.[8] The clouds always occur during the summer season near the poles and the Northern season always starts around the same time. Scientists have found that the start of the Southern season can vary up to a month however.[9]

Noctilucent clouds as seen by AIM
AIM in clean room

References
  1. ESA. "AIM (Aeronomy of Ice in the Mesosphere)". Retrieved 31 March 2020.
  2. "AIM Satellite details 2007-015A NORAD 31304". N2YO. 25 January 2015. Retrieved 25 January 2015.
  3. "NASA AIM web page".
  4. Jeanne Ryba (4 June 2007). "AIM Mission - Launch". NASA. Archived from the original on 16 March 2010. Retrieved 2010-03-16.
  5. Space Dynamics Laboratory (2010). "Programs: AIM – SOFIE". Utah State University Research Foundation. Retrieved 2010-03-16.
  6. "Cosmic Dust Experiment (CDE)". Hampton University. 2010. Retrieved 2010-03-16.
  7. "Solar Occultation For Ice Experiment". GATS, Inc. 2010. Retrieved 2010-03-16.
  8. "AIM — NASA Science". NASA. 2010. Archived from the original on 24 March 2010. Retrieved 2010-03-16.
  9. Fox, Karen. "Clouds, Clouds, Burning Bright". NASA.

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