Discoverer 4

American reconnaissance satellite

Discoverer 4

Mission type| Optical reconnaissance
Operator| US Air Force / NRO
Harvard designation| 1959-U01
SATCAT no.| F00068
Spacecraft properties
Spacecraft type| CORONA KH-1
Bus| Agena-A
Manufacturer| Lockheed
Launch mass| 870 kilograms (1,920 lb) after orbit insertion
Start of mission
Launch date|

‹The template below is included via a redirect (Template:Start-date) that is under discussion. See redirects for discussion to help reach a consensus.›

25 Jun 1959 22:47:45 (1959-06-25UTC22:47:45Z) GMT
Rocket| Thor DM-21 Agena-A
(Thor 179)
Launch site| Vandenberg LC 75-3-5

Discoverer

← Discoverer 3

Discoverer 5 →

Corona KH-1

Discoverer 5 →

Discoverer 4, also known as Corona 9001,[1]: 236  was an American optical reconnaissance satellite launched on 25 Jun 1959 at 22:47:45 GMT, the first of ten operational flights of the Corona KH-1 spy satellite series, and the first satellite to be equipped for photo surveillance. The satellite was not successfully orbited. Its loss spurred improvements of its rocket booster to ensure the success of subsequent missions.

## Background

[edit]

Thor Agena A with Discoverer 4, 25 June 1959.gif

"Discoverer" was the civilian designation and cover for the Corona satellite photo-reconnaissance series of satellites managed by the Advanced Research Projects Agency of the Department of Defense and the U.S. Air Force. The primary goal of the satellites was to replace the U-2 spyplane in surveilling the Sino-Soviet Bloc, determining the disposition and speed of production of Soviet missiles and long-range bombers assess. The Corona program was also used to produce maps and charts for the Department of Defense and other US government mapping programs.[2]

The first series of Corona satellites were the Keyhole 1 (KH-1) satellites based on the Agena-A upper stage, which not only offered housing but whose engine provided attitude control in orbit. The KH-1 payload included the C (for Corona) single, vertical-looking, panoramic camera that scanned back and forth, exposing its film at a right angle to the line of flight.[3]: 26  The camera, built by Fairchild Camera and Instrument with a f/5.0 aperture and 61 centimetres (24 in) focal length, had a ground resolution of 12.9 metres (42 ft). Film was returned from orbit by a single General Electric Satellite Return Vehicle (SRV) constructed by General Electric. The SRV was equipped with an onboard small solid-fuel retro motor to deorbit at the end of the mission. Recovery of the capsule was done in mid-air by a specially equipped aircraft.[4]

Discoverer 4 was preceded by three Discoverer test flights whose satellites carried no cameras.[1]: 51–54

## Spacecraft

[edit]

The battery-powered[4] Discoverer 4 was composed of two sections: the satellite proper and the SRV. Together, they massed (870 kilograms (1,920 lb)) after orbit insertion.[1]: 236  It was the first Discoverer equipped with the C camera and the first satellite built for photo surveillance.[1]: 54

## Mission

[edit]

Launched 25 Jun 1959 22:47:45 GMT from Vandenberg LC 75-3-5 by a Thor-Agena rocket, the satellite was lost when its carrying Agena failed to reach orbit.[1]: 54

## Legacy

[edit]

As a result of the loss of Discoverers 3 and 4 during launch, the Air Force Ballistic Missile Division (BMD) halted flights until the Agena failures could be evaluated. In consultation with Space Technology Laboratories, BMD slightly altered the Agena's propulsion, control, and computer systems. The fuel system of the Thor first stage was also altered. These changes ensured the successful launch of Discoverer 5 in August 1959.[5]

CORONA achieved its first fully successful operational flight with the mission of Discoverer 14, launched on August 18, 1960.[1]: 59  The program ultimately comprised 145 flights in eight satellite series, the last mission launching on 25 May 1972.[1]: 245  CORONA was declassified in 1995,[1]: 14  and a formal acknowledgement of the existence of US reconnaissance programs, past and present, was issued in September 1996.[1]: 4

## References

[edit]

1. ^ a b c d e f g h i Day, Dwayne A.; Logsdon, John M.; Latell, Brian (1998). Eye in the Sky: The Story of the Corona Spy Satellites. Washington and London: Smithsonian Institution Press. ISBN 1-56098-830-4. OCLC 36783934.
2. ^ "Discoverer 1". NASA Space Science Data Coordinated Archive. Retrieved 24 October 2020.
3. ^ "Corona: America's First Satellite Program" (PDF). Central Intelligence Agency. 1995. Archived from the original (PDF) on June 12, 2007. Retrieved 25 January 2020.
4. ^ a b Krebs, Gunter. "KH-1 Corona". Gunter's Space Page. Retrieved 7 November 2020.
5. ^ Robert Perry (October 1973). A History of Satellite Reconnaissance, Volume 1 (PDF). National Reconnaissance Office. pp. 90–91\. OCLC 794229594.

* Spaceflight portal

* v
* t
* e

Discoverer satellites

* 1
* 2
* 3
* 4
* 5
* 6
* 7
* 8
* 9
* 10
* 11
* 12
* 13
* 14
* 15
* 16
* 17
* 18
* 19
* 20
* 21
* 22
* 23
* 24
* 25
* 26
* 27
* 28
* 29
* 30
* 31
* 32
* 33
* 34
* 35
* 36
* 37
* 38

* See also: CORONA (satellite) and KH-5 Argon

* v
* t
* e

Key Hole satellites

KH-1 Corona|

* Discoverer 4
* Discoverer 5
* Discoverer 6
* Discoverer 7
* Discoverer 8
* Discoverer 9
* Discoverer 10
* Discoverer 11
* Discoverer 14
* Discoverer 15

KH-2 Corona'|

* Discoverer 16
* Discoverer 17
* Discoverer 18
* Discoverer 22
* Discoverer 25
* Discoverer 26
* Discoverer 28

KH-3 Corona'''|

* Discoverer 29
* Discoverer 30
* Discoverer 31
* Discoverer 32
* Discoverer 33
* Discoverer 34
* Discoverer 35
* Discoverer 36
* Discoverer 37

KH-4 Corona-M|

| KH-4|

* Discoverer 38
* FTV-1124
* FTV-1125
* FTV-1128
* FTV-1127
* FTV-1129
* FTV-1151
* FTV-1130
* FTV-1131
* FTV-1152
* FTV-1133
* FTV-1153
* FTV-1154
* FTV-1136
* FTV-1135
* FTV-1155
* FTV-1156
* OPS 0048
* OPS 0583
* OPS 0720
* OPS 0954
* OPS 0999
* OPS 1266
* OPS 2268
* OPS 2260
* OPS 1388

|

KH-4A|

* OPS 1419
* OPS 1353
* OPS 3467
* OPS 3444
* OPS 2921
* OPS 3483
* OPS 3754
* OPS 3491
* OPS 3042
* OPS 3497
* OPS 3333
* OPS 3559
* OPS 5434
* OPS 3360
* OPS 3358
* OPS 3928
* OPS 4782
* OPS 4803
* OPS 5023
* OPS 8425
* OPS 8431
* OPS 5543
* OPS 7208
* OPS 7221
* OPS 5325
* OPS 2155
* OPS 7249
* OPS 4639
* OPS 7291
* OPS 3488
* OPS 1612
* OPS 1508
* OPS 1778
* OPS 1599
* OPS 1703
* OPS 1545
* OPS 1866
* OPS 1664
* OPS 4750
* OPS 4779
* OPS 4696
* OPS 3559
* OPS 4827
* OPS 0562
* OPS 2243
* OPS 4849
* OPS 5343
* OPS 0165
* OPS 4740
* OPS 3722
* OPS 1101
* OPS 3531

KH-4B|

* OPS 5089
* OPS 1001
* OPS 1419
* OPS 5955
* OPS 1315
* OPS 3890
* OPS 3654
* OPS 6617
* OPS 0440
* OPS 4720
* OPS 4324
* OPS 4992
* OPS 3297
* OPS 5300
* OPS 5454
* OPS 5640
* OPS 6371

KH-5 Argon|

* Discoverer 20
* Discoverer 23
* Discoverer 24
* Discoverer 27
* FTV-1126
* FTV-1132
* FTV-1134
* OPS 1008
* OPS 1561
* OPS 2437
* OPS 2739
* OPS 3236

KH-6 Lanyard|

* OPS 0627
* OPS 0924
* OPS 1370

KH-7 Gambit|

* OPS 1467
* OPS 1947
* OPS 2196
* OPS 2372
* OPS 2423
* OPS 3435
* OPS 3743
* OPS 3592
* OPS 3684
* OPS 3802
* OPS 4262
* OPS 4036
* OPS 4384
* OPS 4439
* OPS 4703
* OPS 4920
* OPS 4983
* OPS 5236
* OPS 5501
* OPS 5810
* OPS 5698
* OPS 7208
* OPS 6232
* OPS 7253
* OPS 1184
* OPS 0879
* OPS 0910
* OPS 1950
* OPS 1577
* OPS 1850
* OPS 1832
* OPS 1686
* OPS 2055
* OPS 2070
* OPS 1890
* OPS 4399
* OPS 4321
* OPS 4360

KH-8 Gambit|

| KH-8|

* OPS 3401
* OPS 4096
* OPS 8968
* OPS 4204
* OPS 4243
* OPS 4282
* OPS 4886
* OPS 4941
* OPS 4995
* OPS 5000
* OPS 5028
* OPS 5057
* OPS 5105
* OPS 5138
* OPS 5187
* OPS 5247
* OPS 5296
* OPS 6518
* OPS 7585
* OPS 4248
* OPS 5310
* OPS 1077

|

KH-8A|

* OPS 7807
* OPS 8455
* OPS 6531
* OPS 2863
* OPS 6820
* OPS 7874
* OPS 7568
* OPS 7776
* OPS 7899
* OPS 8607
* OPS 7616
* OPS 1678
* OPS 6574
* OPS 8888
* OPS 3978
* OPS 2093
* OPS 4018
* OPS 6275
* OPS 6889
* OPS 1776
* OPS 304
* OPS 4883
* OPS 5499
* OPS 7600
* OPS 8533
* OPS 4915
* OPS 7471
* OPS 7164
* OPS 1166
* OPS 2849
* OPS 2925
* OPS 8424

KH-9 Hexagon|

* OPS 7809
* OPS 1737
* OPS 7293
* OPS 8314
* OPS 8410
* OPS 8261
* OPS 6630
* OPS 6245
* OPS 7122
* OPS 6381
* OPS 4428
* OPS 4699
* OPS 4800
* OPS 0460
* OPS 3854
* OPS 3123
* OPS 5642
* OPS 0721
* USA-2
* #1220

KH-10 Dorian|

* OPS 0855 (mockup)

KH-11 Crystal|

* OPS 5705
* OPS 4515
* OPS 2581
* OPS 3984
* OPS 9627
* USA-6
* #2101
* USA-27
* USA-33
* USA-86
* USA-116
* USA-129
* USA-161
* USA-186
* USA-224
* USA-245

See also
KH-12
Misty
Enhanced Imaging System
USA-53
USA-144

* v
* t
* e

← 1958

Orbital launches in 1959

1960 →

* Mechta
* Vanguard 2
* Discoverer 1
* Pioneer 4
* Discoverer 2
* Unnamed, Unnamed
* Discoverer 3
* Luna E-1A No.1
* Vanguard SLV-6
* Discoverer 4
* Explorer S-1
* Explorer 6
* Discoverer 5
* Beacon 2
* Discoverer 6
* Luna 2
* Transit 1A
* Vanguard 3
* Luna 3
* Explorer 7
* Discoverer 7
* Discoverer 8
* Pioneer P-3

Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets).
*[no.]: number
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template