| definition
| - The Heat Capacity Mapping Mission (HCMM) spacecraft was the first of a series
of Applications Explorer Missions (AEM). The objective of the HCMM was to
provide comprehensive, accurate, high-spatial-resolution thermal surveys of the
surface of the earth. The HCMM spacecraft was made of two distinct modules:
(1) an instrument module, containing the heat capacity mapping radiometer and
its supporting gear, and (2) a base module, containing the data handling,
power, communications, command, and attitude control subsystems required to
support the instrument module. The spacecraft was spin stabilized at a rate of
14 rpm.
The HCMM circular sun-synchronous orbit allowed the spacecraft to sense surface
temperatures near the maximum and minimum of the diurnal cycle. The orbit had
a daylight ascending node with nominal equatorial crossing time of 2:00 p.m.
Since there was no inclination adjustment capacity, the spacecraft drifted from
this crossing time by about 1 hour earlier per year. There was no on-board
data storage capability, so only real-time data were transmitted when the
satellite came within reception range of seven ground stations. The repeat
cycle of the spacecraft was 16 days. Day/night coverage over a given area
between the latitudes of 85 deg N and 85 deg S occurred at intervals ranging
from 12 to 36 h (once every 16 days).
During February 21-23, 1980, the HCMM orbital altitude was lowered from 620 km
to 540 km to stop the drift of the orbit plane to unfavorable sun angles which
in turn reduced the power collection capability of the solar panels. The
operations of the spacecraft were terminated on September 30, 1980. More
detailed information can be found in the 'Heat Capacity Mapping Mission
Users' Guide' (TRF B30282), available from NSSDC.
__________
Taken from the NSSDC System for Information Retrieval and Storage (SIRS). For
more information contact the NSSDC Coordinated Request and User Support Office,
301-286-6695 (NASA Goddard Space Flight Center, Code 933.4, Greenbelt, Maryland
20771, USA)
Group: Platform_Details
Entry_ID: HCMM
Group: Platform_Identification
Platform_Category: Earth Observation Satellites
Short_Name: HCMM
Long_Name: Heat Capacity Mapping Mission
End_Group
Group: Synonymous_Platform_Names
Short_Name: HCMM
Short_Name: AEM-A
Short_Name: Explorer 58
Short_Name: 10818
End_Group
Group: Orbit
Orbit_Inclination: 97.6 degrees
Period: 96.67 min
Perigee: 560 km
Apogee: 641 km
Orbit_Type: LEO > Low Earth Orbit > Polar Sun-Synchronous
End_Group
Creation_Date: 2007-11-19
Online_Resource: http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1978-041A
Sample_Image: http://www.daviddarling.info/images/HCMM.jpg
Group: Platform_Logistics
Launch_Date: 1978-04-26
Launch_Site: Vandenberg Air Force Base, USA
Primary_Sponsor: NASA
End_Group
End_Group (en)
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