Atomic Awesome, Genius Innovators

Bang. Zoom. Straight to the Moon.

In the heady days of early space exploration, NASA was in the business of expanding the world of man out into the solar system. The Moon was going to be the first step in a grand adventure to get to other planets, and then beyond. They knew that the powerful rockets they were currently building were not really suited for this interplanetary travel, and so began an ambitious program to develop better alternatives. Nuclear rockets were the answer, and Harold B. Finger was the man to make it happen.

Harold Finger came on board in 1944, back in the days of NACA, and right away started working with a team to develop sheilding techniques for astronauts in nuclear powered vessels. This team did the installation and testing of a one megawatt nuclear reactor in a B-36 Peacemaker Nuclear Bomber, although it never powered the plane, and the idea of nuclear powered aircraft soon fell out of favor. But space remained as a real possibility. When NASA came into being in 1958, it was considered almost surely that man would ride nuclear rockets out into the solar system, with Mars being the likely first destination. Finger was named manager of the Atomic Energy Commission – NASA Space Nuclear Propulsion Office in 1960, and set to work developing nuclear propulsion systems.

The basic nuclear rocket works like this: a hydrogen propellant passes through a uranium reactor, which converts that hydrogen into plasma. The plasma is ejected out of the rocket nozzle, providing large amounts of thrust at a relatively low system weight. This allows the size of the spacecraft required to travel to another planet to be smaller and lighter. In order to test the system, called the Nuclear Engine for Rocket Vehicle Application, or NERVA, Finger’s office set up in Jackass Flats, Nevada with a series of KIWI reactor engines. Named KIWI after the flightless bird, these rockets were tested in an upside down configuration, generating downward thrust.

Kiwi was a project under the National Nuclear Rocket development program, sponsored jointly by the Atomic Energy Commission and NASA as part of project Rover/NERVA (Nuclear Engine for Rocket Vehicle Application). The main objective of Rover/NERVA was to design a flight rated thermodynamic nuclear rocket engine. Kiwi was a prototype for a nuclear rocket reactor that could be used in space travel. Gaseous hydrogen was used as a propellant on the Kiwi-A tests that began in 1959. Kiwi-A served as a learning tool to test specifications and to discover changes that needed to be implemented in the next phase of study, the Kiwi-B series. This project began in December 1961 and used liquid hydrogen as a propellant. In the late 1960’s and early 1970’s, the Nixon Administration cut NASA and NERVA funding dramatically. The cutbacks were made in response to a lack of public interest in human spaceflight, the end of the space race after the Apollo Moon landing, and the growing use of low-cost unmanned, robotic space probes. Eventually NERVA lost its funding, and the project ended in 1973. (NASA)

KIWI A reactor running during a test.

There were of course concerns for safety, and Finger was an advocate for launching the reactor cold and activating it once in orbit. According to his personal accounts, when pressured to enact some ‘hot’ launch testing, he answered “You may fail. Where is the safe launch site, a remote launch site that you’re willing to sacrifice?” Although he later conceded that the tests that sent jets of hydrogen heated by nuclear reaction directly into the atmosphere would likely cause a bit of controversy today.

Despite this focus on safety, the KIWI program also included a much more unusual test. Here is NASA’s description:

A modified Kiwi nuclear reactor was deliberately destroyed at the Nuclear Rocket Development Station in Jackass Flats, Nevada, as a safety experiment simulating an accident during a launch. Nuclear scientists imposed a sudden increase in power on the generator, there was a rapid release of heat and energy that caused the reactor to burst apart. The safety experiment was designed to obtain basic reactor shutdown information for use in predicting the behavior of nuclear rocket reactors under a wide range of accident conditions. (NASA)

1965 KIWI reactor explosion.

KIWI reactor fallout from 1965.

What might the future hold for nuclear rockets? Harold Finger wrote in 2000, “the technology of nuclear rocket propulsion was fully demonstrated as ready for flight mission applications… Let’s do it!”

Discovered via, images from,, Wikipedia,, GRIN, (x2),, and



  • Judging from the photograph, I'd say Mr. Finger had been suffering from, um… 'chronic' fatigue?

    I think it was called 'KIWI' because New Zealand is upside down, not because it was a flightless bird.

    RE: The last picture…It's 2012! Where are the nuclear rocket powered locomotives you promised?!

  • fodder650

    I thought I had read that actually sent a couple test units into orbit. I need to go look that up again.

  • schigleymischke

    One these days, Alice, one of these days…

  • skitter

    I'm not 100% on the entire process of how it works, but it clearly makes a much bigger FOOM than an ion drive. Therefore, it is far more awesome.

    • Plus they could nuke some burritos on the way!

  • CruisinTime

    What could go wrong?