Atlas-Agena was an American expendable launch system derived from
SM-65 Atlas missile. It was a member of the Atlas family of
rockets, and was launched 109 times between 1960 and 1978. It was
used to launch the first five Mariner unmanned probes to the planets
Venus and Mars, and the Ranger and Lunar Orbiter unmanned probes to
the Moon. The upper stage was also used as an unmanned orbital target
vehicle for the Gemini manned spacecraft to practice rendezvous and
docking. However, the launch vehicle family was originally developed
for the Air Force and most of its launches were classified DoD
Atlas-Agena was a two-and-a-half-stage rocket, with a
stage-and-a-half Atlas missile as the first stage, and an RM-81 Agena
second stage. Initially, Atlas D missiles, redesignated as the LV-3,
were used as the first stage. These were later replaced by the
standardized Atlas SLV-3, and its derivatives, the SLV-3A and B. The
Atlas-Agena launch used an Atlas E/F.
The earliest Agena variant was the Agena A in 1959-60, which did not
have restart capability. Most of these were flown on Thor-Agena
boosters for the Discoverer program and only four used Atlases (Midas
1, Midas 2, Samos 1, and Samos 2), two of which failed.
Late in 1960, Lockheed introduced the uprated Agena B stage which was
restartable and had longer propellant tanks for more burn time. It
first flew on the Thor and did not make its maiden voyage on an Atlas
for months, when Midas 3 launched on July 12, 1961. Atlas-Agenas were
then used for DoD and
NASA programs, but proved a reliability
nightmare as one failure after another happened. In late 1962, after
Ranger 5 suffered another booster malfunction (albeit a minor one that
ground controllers were able to work around),
NASA convened a review
board which undertook a wholesale reevaluation of the
Atlas-Agena as a
launch vehicle. The board found that quality control and checkout
procedures were poor, and that this situation was exacerbated by the
several dozen configurations of the booster, as each individual DoD
NASA program necessitated custom modifications to the Atlas and
Agena, and the latter also differed in its Atlas and Thor variants.
The board recommended improved quality control, better hardware, and
also establishing one standardized launch vehicle for all space
The end result was the
Atlas SLV-3 and Agena D, standardized versions
of the Atlas D core and Agena B which would be the same on every
launch (at least as far as the Atlas was concerned, Agena Ds often
still had customized setups, especially for DoD payloads). The Agena D
first flew in July 1963 for DoD launches, but
NASA continued using
Agena Bs for the remaining Ranger missions. The
Atlas SLV-3 meanwhile
first flew in August 1964. Dozens of Atlas SLV-3/Agena D boosters were
flown over the following years, mostly for the
KH-7 Gambit program,
also for a few
NASA missions. The last
Atlas-Agena was flown in 1978
to launch SEASAT, but on a repurposed Atlas F missile rather than the
Launches were conducted from Launch Complexes 12, 13 and 14 at the
Cape Canaveral Air Force Station, and Launch Complexes 1 and 2 at
Point Arguello (now SLC-3 and 4 at Vandenberg Air Force Base).
2 Destruct system
3 Production launches
3.4 Lunar Orbiter
Atlas LV-3 Agena-A
Atlas-Agena variant flown four times for the Midas and Samos
Atlas LV-3 Agena-B
Enhanced, restartable Agena. Used for a variety of
NASA and Air Force
programs, including Ranger, Mariner, Samos, and Midas.
Atlas LV-3 Agena-D
Standardized Agena B used for a variety of
NASA and Air Force
programs, including Ranger, Mariner, Midas, and Gambit.
Atlas SLV-3 Agena-D
Standardized SLV-3 Atlas+Agena D used for a variety of
NASA and Air
Force programs, including Mariner, Vela, and Gambit.
Atlas SLV-3B Agena-D
One-off Atlas variant used for the first OAO satellite.
Atlas SLV-3 Agena-B
One-off Atlas variant used for OAO-3
Atlas SLV-3A Agena-D
Extended tank Atlas. Used for OGO-5 and Canyon/Rhyolite SIGNIT
Atlas E/F Agena D
One-off Atlas variant mating the last Agena stage flown to a
refurbished Atlas F missile for the launch of Seasat.
Atlas-Agena vehicles contained an Inadvertent Separation Destruct
System to destroy the Agena in the event that it separated prematurely
from the Atlas, a situation that could be caused by a booster
hard-over or if the Atlas self-destructed in flight. The ISDS charges
were mounted on the adapter section between the two vehicles and would
activate if a series of tripwires were broken. During the coasting
period between staging, the ISDS charges were disabled. The Atlas's
own RSO charges were also wired so that they would destroy both
vehicles if activated. Most Agenas also had their own separate RSO
NASA planetary probes omitted them for weight-saving
reasons and due to the flight trajectory used, which meant that
destruct of the Agena was no longer possible following staging.
Atlas-Agena flights involved an intentional destruct of the Atlas
Mariner 1 and Canyon 4) while two others (Midas 6 and Midas 8)
resulted in an ISDS destruction of the Agena following in-flight
malfunction and self-destruct of the Atlas.
The Gemini-Agena Target Vehicle had a specially modified Range Safety
destruct system designed to fire slugs into the propellant tanks
rather than the conventional method of rupturing them externally,
since an inadvertent activation of the RSO system in orbit could
endanger the Gemini astronauts.
The very first
Atlas-Agena flight, Midas 1 in February 1960, failed
when the unproven ISDS system mistakenly activated at staging,
rupturing the Atlas's
LOX tank and causing the breakup of the Agena.
The ISDS system was redesigned afterwards and this failure mode did
not repeat itself.
Main article: Ranger program
Ranger block I spacecraft bus was used for the first two Rangers, and
also for the first two Mariner interplanetary probes
The Ranger spacecraft were designed to impact the Moon, returning
photographs of the lunar surface until their destruction. The
spacecraft was designed in three Blocks, all similar in appearance
with a forward antenna and magnetometer, supported by a boom, with
more sensors and two solar panels and a dish antenna mounted at the
base. The first two Block I spacecraft,
Ranger 1 and Ranger 2, were
launched on August 23 and November 18, 1961, not to the Moon, but in
intended high Earth orbits to test the
Atlas-Agena and spacecraft
capabilities. However, the Agena malfunctioned on both flights and
left the probes trapped in a useless low Earth orbit from which they
The Block II missions, Ranger 3, Ranger 4, and Ranger 5, were launched
away from Earth in January, April, and October 1962, but all three
failed due to either malfunctions of the probe or launch vehicle
Ranger 3 missed the Moon entirely. Ranger 4's solar
panels failed to deploy, and the navigation system failed, sending the
probe to impact the lunar far side without returning any pictures or
Ranger 5 suffered an unknown failure which deprived it of power,
and it missed the Moon by 725 kilometers (391 nautical miles).
Ranger 6, launched January 30, 1964, successfully impacted the Moon
but its cameras failed to return pictures. The last three Rangers were
Ranger 7 in July 1964,
Ranger 8 in February 1965,
Ranger 9 in March 1965.
Main article: Mariner program
The Mariner spacecraft were built by NASA's Jet Propulsion Laboratory.
Mariner 1 and
Mariner 2 were twins, launched on July 22 and August 27,
1962, to fly by the planet Venus. The first two craft used the same
spacecraft bus as the Block I Rangers, each weighing 446 pounds
(202 kg) and instrumented to perform radiometric temperature
measurements of the planet, and to measure interplanetary magnetic
fields and particles. Mariner 1's
Atlas-Agena malfunctioned and
went off course, requiring its destruction approximately 5 minutes
Mariner 2 successfully made the 3½-month flight,
becoming the first spacecraft to fly by another planet. It carried
microwave and infrared radiometers, and sensors for cosmic dust, solar
plasma and high-energy radiation, and magnetic fields.
Mariner 3, 4, and 5 spacecraft bus
Mariner 3 and
Mariner 4 used a redesigned spacecraft bus weighing 575
pounds (261 kg), and were launched on November 5 and November 28,
1964 to fly by the planet Mars.
Mariner 3 failed after a successful
launch when its payload shroud failed to open. These Mariners carried
Mariner 4 successfully returned pictures of
Mars as it
The 540-pound (240 kg)
Mariner 5 was successfully launched to
Venus on June 14, 1967 and flew by in October, probing Venus'
atmosphere with radio waves, scanning its brightness in ultraviolet
light, and sampling solar particles and magnetic field fluctuations
above the planet.
Main article: Agena target vehicle
The Agena Target Vehicle as seen from
Gemini 8 during rendezvous,
March 16, 1966
The Agena rocket stage was used as the passive docking target for the
Gemini manned space program. After docking, the Agena could also be
fired by the astronauts to raise the combined Gemini-Agena spacecraft
into a higher orbit. The first attempt at such a docking mission was
made for the
Gemini 6 mission on October 25, 1965, but the Agena
suffered an engine failure and did not reach orbit. This forced
postponement and replanning of the Gemini 6A mission, which performed
Gemini 7 without docking.
The GATV was first successfully launched for
Gemini 8 on March 16,
1966, permitting the first successful docking in space. GATV-8 was
later used as the secondary Agena target for Gemini 10, which also
docked with its own GATV. GATV-9 failed to orbit when the Atlas
suffered a control malfunction, forcing a similar reschedule of the
Gemini 9A mission using a backup
Augmented Target Docking Adapter
Augmented Target Docking Adapter atop
an Atlas, but with no Agena rocket stage. Two more GATVs were
successfully launched and used on
Gemini 11 and Gemini 12.
Main article: Lunar Orbiter program
Lunar orbiter spacecraft (NASA)
A series of five Lunar Orbiter spacecraft were launched from August
1966 through August 1967, to help select landing sites for the Apollo
manned lunar landing program by mapping the Moon's surface. Each
spacecraft weighed 850 pounds (390 kg) and was 4.9 feet
(1.5 m) in diameter, minus the four extended solar panels. All
launches were successful, and a total of 99 percent of the surface of
the Moon (near and far side) was mapped with resolution as high as
3 ft 3 in (1 meter). Altogether the Orbiters returned 2180 high
resolution and 882 medium resolution frames. The spacecraft also
carried micrometeroid sensors, which showed the average
micro-meteoroid flux near the Moon to be two orders of magnitude
greater than in interplanetary space, but slightly less than the
Orbiting Astronomical Observatory
Orbiting Astronomical Observatory was a series of
flown between 1966 and 1972 for astronomy studies. The first OAO
(launched April 8, 1966) used a one-off Atlas variant, mating an Agena
D to the LV-3C variant of the Atlas and encased in a Centaur-type
payload shroud. The remaining three launches used actual Atlas-Centaur
Applications Technology Satellite was a series of
flown in 1967-69 to perform various technology tests. Only the first
ATS was launched on an Atlas-Agena, the remainder using
Atlas-Centaurs. ATS-1 was a partial failure when the Agena failed to
restart, leaving it in LEO.
Orbiting Geophysical Observatory
Orbiting Geophysical Observatory was a series of
NASA satellites flown
between 1964 and 1969 for magnetosphere studies. These satellites used
several different booster types, including Thor-Agenas. Five of them
used Atlas-Agenas, and OGO 5 (launched March 4, 1968) was the sole
civilian use of the Atlas SLV-3A Agena.
Missile Defense Alarm System
Missile Defense Alarm System was a series of Air Force satellites
flown between 1960 and 1966 for infrared detection of ballistic
missile exhaust plumes on
Atlas-Agena A, B, and D. There were several
failures and overall program performance was poor, but it would give
way to the more successful DSP satellites.
Samos was a series of Air Force satellites flown between 1960 and 1962
for photoreconnaissance on
Atlas-Agena A and B. There were several
failures, including an on-pad explosion of an Atlas, and the program
was cancelled at the end of 1962 without ever demonstrating any
KH-7 Gambit was a series of Air Force satellites flown between 1963
and 1966 for photoreconnaissance on
Atlas-Agena D. Although there were
a number of mission failures, Gambit overall was highly successful in
comparison with the bungled Samos program and it returned high-value
area reconnaissance of the USSR and China before giving way to KH-8
Gambit in 1967.
Rhyolite/Canyon was a series of Air Force satellites flown between
1968 and 1978 for SIGNIT intelligence on Atlas SLV-3A Agena. One
Canyon mission failed when its Atlas went off course and had to be
destroyed. These were the final launches of
Atlas-Agena vehicles aside
from the one-off Atlas F/Agena used to launch Seasat.
Vela consisted of two sets of Air Force satellites flown in 1964-65 to
monitor Soviet compliance with the Nuclear Test Ban Treaty on
Snapshot was a one-off Air Force test of a nuclear satellite flown in
1965 on an
^ Encyclopedia Astronautica - Atlas
^ Gunter's Space Page - Atlas Agena
^ "Tracking Information Memorandom: Mariner R 1 and 2" (PDF). NASA
Technical Reports Server. Retrieved December 29, 2011.
^ "Mariner R Spacecraft for Missions P-37/P-38" (PDF).
Reports Server. Retrieved December 29, 2011.
Gemini 6 Target - NSSDC ID: GEM6T".
^ Barton C. Hacker and James M. Grimwood (1977). "On The Shoulders of
Titans: A History of
Project Gemini - The Visitors". NASA.
^ Bowker, David E. and J. Kenrick Hughes, Lunar Orbiter Photographic
Atlas of the Moon ,
NASA SP-206 (1971).
Francis E. Warren
Common Core Booster
Pratt & Whitney
International Launch Services
United Launch Alliance
Orbital launch systems
v1.2 "Full Thrust"
2.1a / STA
2.1b / STB
Falcon 9 Block 5
New Line 1
Feng Bao 1
4S 3C 3H 3S 3SII
List of orbital launch systems
Comparison of orbital launch systems
Orbital launch systems developed in the United States
v1.2 "Full Thrust"
Falcon 9 Block 5
* - Japanese projects using US rocke