Atlas Chronology

[WallE]

Atlas 105D/Agena 1202 ("Big Town") launched from PALC 1-2 on October 21, 1961, carrying the fourth MIDAS satellite and the last "open" mission before the early warning and intelligence-gathering satellite programs were made top secret. The flight was normal throughout booster phase and part of sustainer phase; at T+186 seconds the Atlas lost roll control. The booster rolled about 8-1/2 times before staging. As pitch and yaw stability were maintained, the booster was able to complete its burn on time and place the Agena and satellite vehicle on the proper flight trajectory, but the latter ended up using a significant amount of attitude control gas correcting the roll imparted into it by the Atlas. Once in orbit, a malfunction of the Agena horizon sensor combined with the control gas depletion caused an uncontrolled rotation in the pitch plane.

MIDAS 4 successfully detected the launch of a Titan I from Cape Canaveral on October 24; shortly afterwards, one solar panel failed. The satellite vehicle's batteries ran down and the mission was ended in a week. The horizon sensor on the Agena was modified afterward. The Atlas roll control issue was concluded to be the result of one of the booster retrorocket heat shields falling off and exposing transistors in the gyro package to aerodynamic heating, causing their failure. After a repeat of this failure on SAMOS 4 a month later, except in that case the satellite vehicle didn't even make it to orbit, the heat shields were redesigned and the transistors replaced with a different type less prone to thermal runaway.

"Agena Flight History as of 31 December 1967" describes the roll control issue as being largely responsible for the mission failure as it caused the expenditure of most of the Agena's control gas in order to correct it despite GD/A docs claiming it had no effect on anything.

[WallE]

Atlas 70D is raised on PALC 1-2 on August 26, 1960 in preparation for SAMOS 2. The booster launched January 31, 1961, a chilly, gray, overcast winter day and it was out of visibility within 40 seconds. Atlas and Agena performance were normal and the electroscan photo system was tried out, but all T/M was abruptly lost on orbit 21 during an attempted antenna deployment, apparently the antenna separation mechanism caused major damage to or the total disintegration of the satellite. The dead satellite vehicle remained in orbit for 12 years before decaying. The fuzzy images returned from SAMOS 2 were of little value except as a tech demo.

This was also the final launch of the original non-restartable Agena A, which required a direct ascent trajectory to polar orbit. The improved Agena B, which would allow placing the payload in a LEO parking orbit first, had begun flying on Thor vehicles the previous October.

The electroscan system was tried out again on the 7th through 11th SAMOS satellites after a reversion to a conventional film capsule system on 4-6 but the poor quality images were of little use for reconnaissance and the program was abandoned at the end of 1962 by which point CORONA was performing with a high degree of reliability and returning valuable image data.

[WallE]

Atlas 45D/Agena 1007 launched the second MIDAS satellite from Pad 14 at Cape Canaveral on May 24, 1960. As the first MIDAS attempt three months ago had been lost due to an apparent malfunction of the Agena ISDS, it was removed from Vehicle 1007 while being redesigned. Operational MIDAS satellites would be polar orbiting but this was merely a test model to verify the system's functionality and polar orbit was not possible from the Cape so it was launched into a 33 deg orbit.

This was the second East Coast Atlas launch since the twin 51D/48D disasters and special measures were undertaken such as restoring the turbine exhaust ducts to the pads, going back to a wet engine start, having an extended hold down time between engine start and launcher release, and putting extra cameras around the pad, including on the launcher heads (some photos of MIDAS 2's launch show this more clearly than others).

The Atlas and Agena performed well throughout powered flight. In orbit, the satellite vehicle became unstable due to propellant venting which the Agena's attitude control system was unable to compensate for. The infrared sensor returned some data until a probable multicoupler malfunction resulted in completely garbled T/M after orbit 4. Part of the mission plans included detecting a Titan I launch as well as detecting flares on the ground; they could not be carried out due to the T/M failure. What had been a planned 40 month mission, to conclude in September 1963, ended in a mere two days. MIDAS 2 remained in orbit until reentering in 1974.

The operational MIDAS program, to use Agena B, would be moved to VAFB and Pad 14 was turned completely over to NASA and Project Mercury after this launch.

[WallE]

It's apparent from this that there was little improvement a decade after NASA lodged numerous complaints about the quality control of Atlases during the Ranger/Mariner 2 days. Launch vehicles were still requiring extensive modification and repair work at factory acceptance testing and after delivery to Cape Canaveral before they could be deemed flight-ready, and a few times like with Mariner 8 a hardware fault still eluded ground testing and caused loss of the mission.

[Big RI Joe]

I hope this might be of interest

[Big RI Joe]

I have to ask: regarding all these premature cutoff issues: If the flight did not end up going the full range to its intended hostile target would the warhead still explode?

[Proponent]

I would think not. Especially given 1950s reliability, there must be a very reliable way of ensuring that an ICBM launched from Arizona toward Moscow did not blow up Fargo, North Dakota.

[WallE]

I would think not. Especially given 1950s reliability, there must be a very reliable way of ensuring that an ICBM launched from Arizona toward Moscow did not blow up Fargo, North Dakota.

ICBM reliability was only expected to be about 75%. As we have mentioned, quality control on Atlas vehicles always seems to have been pretty bad outside man-rated Mercury boosters where rigid quality standards were enforced. The SLV versions did undergo preflight checks but Atlas missiles were always the low man on the totem pole.

Titan was not any better, the Martin-Marietta plant in Denver was well known to have abominable workmanship and production of Titan II GLVs was moved to a different facility in Maryland to ensure maximum quality control. To be fair Titan SLVs were mostly extremely dependable until the Shuttle caused the planned phase-out of them and quality control collapsed.

And no, nuclear warheads have arming mechanisms on them, actually getting them to detonate/perform fission of the radioactive material is not that easy. If one fell off an exploding missile it's not going to just go off. At most you'd have a conventional explosion like Bluegill Prime when the RSO blew up the warhead on the pad and it just sprayed plutonium everywhere.

[Big RI Joe]

But what about an Atlas ICBM whose sustainer shut down early? The warhead would survive reentry, but would it detonate far short of its intended target?

[Jim]

ICBM reliability was only expected to be about 75%. As we have mentioned, quality control on Atlas vehicles always seems to have been pretty bad outside man-rated Mercury boosters where rigid quality standards were enforced. The SLV versions did undergo preflight checks but Atlas missiles were always the low man on the totem pole.

Titan was not any better, the Martin-Marietta plant in Denver was well known to have abominable workmanship

that isn't true.
a.  Weapon system reliability was 75%.  Not just ICBMs.
b.  Quality control wasn't as bad as you state for either.