Atomic Awesome

Starfish Prime: Apollo’s Other Nuclear Concern

The Starfish Prime high-altitude nuclear test explosion on July 9, 1962.

On July 9, 1962 the US set off one of the largest nuclear bombs in low earth orbit ever. Part of it was experimental, but part of it was meant to inject nuclear radiation into the Van Allen radiation belts that encompass the Earth. The US was thinking that if the radiation level in the Van Allen belts could be raised then Soviet ICBMs that travel through the Van Allen belts would be fried and not destroy us.

The nuclear explosion was huge, visible as far away as Tonga and causing a red aurora over much of the South Pacific. The lasting effects of the radiation in the Van Allen belts was also a concern for NASA several years later.

A few days after Starfish Prime, the US launched Telstar 1 and ushered in a new era for communications. Telstar 1 was operational, circling the globe in the Van Allen radiation belt, until December. It was determined that the increase in radiation from Starfish Prime and Soviet atmospheric tests fried the delicate transistors. This was the first casualty.

A few months after Starfish Prime, President Kennedy committed the US to going to the moon. That means sending men through the Van Allen radiation belts. The ones we just made more radioactive. The ones that just fried a satellite. Crap.

The first question on everyone’s mind was how long the radioactive effects of Starfish Prime would last. Some estimates said the radiation wouldn’t fully dissipate until 1967 or 1968…right when we would be launching astronauts. Crap.

In a report delivered to NASA in October 1962, D. B. James and H. J. Schulte, researchers with Bellcomm, reported on their analysis of the effects of Starfish Prime on the moon mission plans. At the time, two concepts were being debated — Lunar-Orbit Rendezvous or Earth-Orbit Rendezvous. LOR is what NASA eventually went with. It involved launching a command module, lunar lander, and service module. In lunar orbit, the command and service modules would separate from the lunar lander, turn around and rendezvous with the lunar module for crew transfer. In Earth-Orbit Rendezvous, the three modules would be one unit that would rendezvous in Earth orbit with a fuel system launched ahead of time to top off its tanks before heading for the moon.

Mr. James and Mr. Schulte found that in EOR the minimum time in orbit around the Earth was 6 orbits. The last two would pass right through a portion of the Van Allen belts that passed within 100 miles of the Earth’s surface, giving the astronauts a 4-rad does of radiation. In the LOR scheme, the astronauts would only receive 0.02 rad. Both schemes exposed the astronauts to 16 rad as they left Earth orbit and headed for the moon.

For those of you who don’t know, 4 rad is the limit for exposure to radiation before a lemur turns homicidal. 5 rad is the current OSHA annual limit for adult exposure to radiation. NASA set the limit for astronauts on the space shuttle to 25 rad.

Ultimately, NASA chose the LOR scheme, and the Van Allen belts returned to normal a few years after Starfish Prime never to threaten the well-being of our astronauts. In 1963, the US and Soviet Union entered into the Treaty Banning Nuclear Weapon Tests in the Atmosphere, Outer Space, and Under Water, and ceased all atmospheric nuclear tests.

The world before we really understood the effects and longevity of nuclear weapons was a different world than we live in today. It was a combination of naïveté, ignorance, sabre rattling, and exploration that led to these tests, and a combination of diplomacy and knowledge that led to the end of these tests. In short, it was both the best and worst of human existence all rolled into one weird saga.

[Image Credit: Public Domain]

  • jeepjeff

    Thanks for posting this! How did I not know about this test!? It looks like a clear contender for 2nd Favorite Nuclear Weapon Test (yes, I have that list, doesn't everyone here? Also: #2 because Castle Bravo is hard to beat, considering its status as "Most Successful Military Fuck-Up of All Time").

    EDIT: "Military" only in that Castle Bravo was a military test, the physicists ended up being the cause of the miscalculation.

    • tonyola

      But what about the Tsar Bomba? Isn't that the coolest simply because it was 50 megatons of nation-melting fury?

      • texlenin

        The Tsar wasn't miscalculated, they
        deliberately hobbled it- it was rated
        at 150M.
        Even the little Georgian thought that
        might be a bit much.

        • tonyola

          Actually the Tsar Bomba was originally intended to be 100 megatons, not 150. Also, the little Georgian was over eight years dead by the time it was set off – this was Nikita's baby.

          • texlenin

            See, this is what happens when one does not
            fact check late at night. I got the tamper plates
            right, but blew it on the megatonnage and the
            fact the Nikita K was Ukranian, not Georgian
            as well.
            Me talk pretty one day-herp derp.

        • jeepjeff

          As tonyola mentioned, it was rated at 100Mt for its complete design. This included a gigantic U-238 tamper on the outside of the bomb as a tertiary fission stage. Thermonuclear bombs normally have 2-3 stages: a small fission primary to set off the large fusion secondary (Lithium Deuteride). U-238 has a small cross-section for fission by fast neutrons, so if you build the case (tamper) out of depleted uranium, you get a "free" tertiary fission stage from the fast neutrons flying off the fusion stage interacting with the U-238.

          When the blew the Tsar Bomba, they deliberately removed the tamper, because it would cause way too much dirty fallout from the test. There was a good reason to hobble it.

          Also, it was just flag waving and sabre rattling. It also went completely according to plan. Castle Bravo was 2.5x as big as predicted (and a massive 15Mt), our biggest test and it discovered a new set of fusion reaction paths that we didn't know about before. Real science (that could yet prove useful for peaceful purposes) was discovered in the CB test. The not-awesome parts were: people got radiation poisoning and there were a few fatalities, but in some ways that just makes it a more fascinating test, as it really combines everything that was a problem with nuclear tests, even while it proved to be a wildly successful test from an engineering and scientific perspective. The Tsar Bomba is just big.

          • tonyola

            Yeah, but the Tsar Bomba broke windows as far away as Norway and Finland – that's over 600 miles. The mushroom cloud went 40 miles up into the atmosphere. Even though it was an aerial burst, the seismic shock wave was equivalent to a 5.5-magnitude earthquake. Wow.

          • Number_Six

            Even the reduced explosion of the Tsar Bomba terrified Andrei Sakharov, the bomb designer who eventually became an outspoken anti-nuclear activist. This wasn't a popular stance in the USSR and Dr Sakharov was exiled and kept under virtual house arrest in Gorky from 1980 until 1986.

  • <img src="; width="500">

    I never knew how topical this movie was! Very cool article, seems like somebody might would have wanted to notice that if it was going to cause trouble for the Russians it just might cause a little bit for the forces of Truth, Justice, and the American Way!

    • B72

      It gets my vote for the giant squid alone!

      • texlenin

        Somebody should do a VTtBotS/Ice Station Zebra
        youtube mash-up.
        Patrick Mcgoohan vs Walter Pidgeon!