Global Positioning Satellite, also called Navstar (NAVigation
System using Timing And Ranging)
American navigation satellite program operated by USAF. The satellites were
placed by pairs on 20200 km circular orbits to provide localization (with 10 m
precision). They were equipped with atomic clocks.
The program started with the launch between 1978 and 1985 of 10 satellites:
block 1 (BI). Those enabled to check the concept and helped design the first
operational generation. In 1987 28 block 2 (BII) satellites were ordered to
Rockwell (9 BII and 19 BIIA, lifetime: 7 years). On 8 Dec 1993 the system was
operational with 24 satellites available (4 satellites (slots) on 6 planes
60° apart). In 1989 Lockheed Martin (GE Astro Space) was ordered 21
satellites for the Block 2R (BIIR), for a total value of $800 million. The
Block 2R satellites weigh about 2000 kg and have 10 years lifetime. They can
operate during 180 days without groundstation intervention.
After the success encountered by the system in the civilian world, a new policy
was taken in 1996 to stop degrading civil GPS signals within the next decade.
This policy was applied in May 2000 with still certain areas remaining with
degraded signal.
12 2R satellites should be launched from 2001 on with modifications. Those
satellites should have a second civilian frequency (1227.60 MHz) and 2 new
military signals. The modification contract is worth $53 million, held by
LMSS.
The Block 2F satellites are to be provided by Boeing under a $1.3 billion
contract. A third civilian frequency is planned at 1176.45 MHz.
Planes and slots
|
Plane
|
Slot
1
|
Slot
2
|
Slot
3
|
Slot
4
|
Slot
5
|
|
A
|
2-21
|
2-12
|
2-28
|
2-15
|
2-04
|
|
B
|
2-18
|
2-27
|
2-02
|
2-22
|
2R-05
|
|
C
|
2-24
|
2-25
|
2-19
|
2-20
|
|
|
D
|
2-11
|
2R-03
|
2-05
|
2-23
|
2-09
|
|
E
|
2R-04
|
2-08
|
2-26
|
2R-07
|
2-10
/ 2-03
|
|
F
|
2R-06
|
2-14
|
2R-02
|
2-16
|
2-17
|
External links:
Ref: #98 - update: 29.03.15