Nov. 1, 1952: First Hydrogen Bomb Test

Ivy Mike was the codename given to the first test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. It was detonated on November 1, 1952 by the United States on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and was the first successful test of a hydrogen bomb.

The blast created a crater 6,240 feet (1.9 km) in diameter and 164 feet (50 m) deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to twenty feet high) stripped the test islands clean of vegetation, as observed by a helicopter survey within 60 minutes after the test, by which time the mushroom cloud and steam were blown away. Radioactive coral debris fell upon ships positioned 35 miles (48 km) from the blast, and the immediate area around the atoll was heavily contaminated for some time. Produced by intensely concentrated neutron flux about the detonation site were two new elements, einsteinium and fermium.

The nuclear explosion was photographed by high-speed rapatronic cameras less than 1 millisecond after detonation. Developed by Dr. Harold Edgerton in the 1940s, the rapatronic photographic technique allowed nuclear explosion’s fireball growth to be recorded on film. The exposures were often as short as 10 nanoseconds, and each rapatronic camera would take exactly one photograph.

9.3 megatons Hardtack-Poplar nuclear fireball (1958). This was the fifth largest nuclear explosion in U.S. history.

Nuclear explosions emit large amounts of thermal radiation as visible, infrared, and ultraviolet light, to which the atmosphere is largely transparent. This is known as “Flash”.

About 5% of the energy released in a nuclear air burst is in the form of ionizing radiation: neutrons, gamma rays, alpha particles and electrons moving at speeds up to the speed of light. Gamma rays are high energy electromagnetic radiation; the others are particles that move slower than light. The neutrons result almost exclusively from the fission and fusion reactions, while the initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products.

The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst because the radiation spreads over a larger area as it travels away from the explosion (the inverse squared law). It is also reduced by atmospheric absorption and scattering.

'Hardtack Umbrella' underwater nuclear test

Operation HARDTACK I consisted of 35 nuclear tests conducted at the Pacific Proving Ground between April 28 and August 18, 1958. These tests included balloon, surface, barge, underwater, and rocket-borne high-altitude tests.

Umbrella was a DOD sponsored weapons effects test for a medium depth underwater explosion. A Mk-7 bomb was used for the test (30 inches in diameter, 54 inches long, device weight 825 lb.) in a heavy pressure vessel (total weight 7000 lb.). Very similar to the Wahoo device. The device was detonated on the lagoon bottom NNE of Mut (Henry) Island. An underwater crater 3000 feet across and 20 feet deep was produced.

The purpose of these tests was to improve the understanding of the effects of underwater explosions on Navy ships and material.

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Pioneer Venus Artwork 

Artist’s concept of Pioneer Venus mission approaching the planet.
During a 14-year orbit of Venus, Pioneer Venus 1 used radar to map the surface at a resolution of 75 km (47 miles). It found the planet to be generally smoother than Earth, though with a mountain higher than Mt. Everest and a chasm deeper than the Grand Canyon. The orbiter also found Venus to be more spherical than Earth, consistent with the planet’s much slower rotation rate (one Venus day equals 243 Earth days). It confirmed that Venus has little, if any, magnetic field and found the clouds to consist mainly of sulfuric acid. Measurements of this chemical’s decline in the atmosphere over the course of the mission suggested that the spacecraft arrived soon after a large volcanic eruption, which may also account for the prodigious lightning it observed.
After a course correction on 16 August 1978, Pioneer Venus 2 released the 1.5-m diameter large probe on 16 November 1978, at about 11.1 million km from the planet. Four days later, the bus released the three small probes while 9.3 million km from Venus. All five components reached the Venusian atmosphere on 9 December 1978, with the large probe entering first.
Data from the probes indicated that between 10 and 50 km, there is almost no convection in the Venusian atmosphere. Below a haze layer at 30 km, the atmosphere appears to be relatively clear. Amazingly, two of three probes survived the hard impact. The so-called Day Probe transmitted data from the surface for 67.5 minutes before succumbing to the high temperatures and power depletion.

Credit: NASA/Rick Guidice

Pioneer Venus Artwork

Artist’s concept of Pioneer Venus mission approaching the planet.

During a 14-year orbit of Venus, Pioneer Venus 1 used radar to map the surface at a resolution of 75 km (47 miles). It found the planet to be generally smoother than Earth, though with a mountain higher than Mt. Everest and a chasm deeper than the Grand Canyon. The orbiter also found Venus to be more spherical than Earth, consistent with the planet’s much slower rotation rate (one Venus day equals 243 Earth days). It confirmed that Venus has little, if any, magnetic field and found the clouds to consist mainly of sulfuric acid. Measurements of this chemical’s decline in the atmosphere over the course of the mission suggested that the spacecraft arrived soon after a large volcanic eruption, which may also account for the prodigious lightning it observed.

After a course correction on 16 August 1978, Pioneer Venus 2 released the 1.5-m diameter large probe on 16 November 1978, at about 11.1 million km from the planet. Four days later, the bus released the three small probes while 9.3 million km from Venus. All five components reached the Venusian atmosphere on 9 December 1978, with the large probe entering first.

Data from the probes indicated that between 10 and 50 km, there is almost no convection in the Venusian atmosphere. Below a haze layer at 30 km, the atmosphere appears to be relatively clear. Amazingly, two of three probes survived the hard impact. The so-called Day Probe transmitted data from the surface for 67.5 minutes before succumbing to the high temperatures and power depletion.

Credit: NASA/Rick Guidice

Mariner 2 Launch 

Mariner 2 was the first successful mission to another planet by any country. Launched just 36 days after the failure of its twin, Mariner 1, it flew by Venus as planned at a range of 34,762 km (21,600 miles), scanning the planet’s atmosphere and surface for 42 minutes.
The spacecraft showed that surface temperature on Venus was at least 797 degrees Fahrenheit (425 degrees Celsius) on both the day and night sides, hot enough to melt lead. It also showed that Venus rotates in the opposite direction from most planets in our solar system, has an atmosphere mostly of carbon dioxide with very high pressure at the planet’s surface, continuous cloud cover, and no detectable magnetic field. It also found the solar wind streams continuously and that the density of cosmic dust between planets is much lower than it is near Earth.

Credit: Jet Propulsion Laboratory

Mariner 2 Launch

Mariner 2 was the first successful mission to another planet by any country. Launched just 36 days after the failure of its twin, Mariner 1, it flew by Venus as planned at a range of 34,762 km (21,600 miles), scanning the planet’s atmosphere and surface for 42 minutes.

The spacecraft showed that surface temperature on Venus was at least 797 degrees Fahrenheit (425 degrees Celsius) on both the day and night sides, hot enough to melt lead. It also showed that Venus rotates in the opposite direction from most planets in our solar system, has an atmosphere mostly of carbon dioxide with very high pressure at the planet’s surface, continuous cloud cover, and no detectable magnetic field. It also found the solar wind streams continuously and that the density of cosmic dust between planets is much lower than it is near Earth.

Credit: Jet Propulsion Laboratory

Ed White: First American Spacewalker

On June 3, 1965 Edward H. White II became the first American to step outside his spacecraft and let go, effectively setting himself adrift in the zero gravity of space. For 23 minutes White floated and maneuvered himself around the Gemini spacecraft while logging 6500 miles during his orbital stroll. White was attached to the spacecraft by a 25 foot umbilical line and a 23-ft. tether line, both wrapped in gold tape to form one cord. In his right hand White carries a Hand Held Self Maneuvering Unit (HHSMU) which is used to move about the weightless environment of space. The visor of his helmet is gold plated to protect him from the unfiltered rays of the sun.

Credit: NASA

Ed White: First American Spacewalker

On June 3, 1965 Edward H. White II became the first American to step outside his spacecraft and let go, effectively setting himself adrift in the zero gravity of space. For 23 minutes White floated and maneuvered himself around the Gemini spacecraft while logging 6500 miles during his orbital stroll. White was attached to the spacecraft by a 25 foot umbilical line and a 23-ft. tether line, both wrapped in gold tape to form one cord. In his right hand White carries a Hand Held Self Maneuvering Unit (HHSMU) which is used to move about the weightless environment of space. The visor of his helmet is gold plated to protect him from the unfiltered rays of the sun.

Credit: NASA

Cosmic rays discovered 101 years ago

In 1911 and 1912 Austrian physicist Victor Hess made a series of ascents in a hot-air balloon to take measurements of radiation in the atmosphere. He was looking for the source of ionizing radiation that registered on an electroscope – the prevailing theory was that the radiation came from the rocks of the Earth.
To test the theory, in 1909 German scientist Theodor Wulf measured the rate of ionization near the top of the Eiffel tower (at a height of about 300 metres) using a portable electroscope. Though he expected the ionization rate to decrease with height, Wulf noted that the ionization rate at the top was just under half that at ground level – a much less significant decrease than anticipated.
Victor Hess was one person to go further by taking electroscopes up in a balloon. In 1911 his balloon reached an altitude of around 1100 metres, but Hess found “no essential change” in the amount of radiation compared with ground level. Then, on 7 August 1912, in the last of seven flights that year, Hess made an ascent to 5300 metres. There he found the rate of ionization was some three times that at sea level and concluded that penetrating radiation was entering the atmosphere from above. In an earlier flight he had found no noticeable drop during a partial solar eclipse, so he could rule out the Sun as the source. Hess had in fact discovered a natural source of high-energy particles: cosmic rays.
Find out more about cosmic rays (from the CERN courier):
A discovery of cosmic proportions
Domenico Pacini and the origin of cosmic rays
LHCf: bringing cosmic collisions down to Earth

Cosmic rays discovered 101 years ago

In 1911 and 1912 Austrian physicist Victor Hess made a series of ascents in a hot-air balloon to take measurements of radiation in the atmosphere. He was looking for the source of ionizing radiation that registered on an electroscope – the prevailing theory was that the radiation came from the rocks of the Earth.

To test the theory, in 1909 German scientist Theodor Wulf measured the rate of ionization near the top of the Eiffel tower (at a height of about 300 metres) using a portable electroscope. Though he expected the ionization rate to decrease with height, Wulf noted that the ionization rate at the top was just under half that at ground level – a much less significant decrease than anticipated.

Victor Hess was one person to go further by taking electroscopes up in a balloon. In 1911 his balloon reached an altitude of around 1100 metres, but Hess found “no essential change” in the amount of radiation compared with ground level. Then, on 7 August 1912, in the last of seven flights that year, Hess made an ascent to 5300 metres. There he found the rate of ionization was some three times that at sea level and concluded that penetrating radiation was entering the atmosphere from above. In an earlier flight he had found no noticeable drop during a partial solar eclipse, so he could rule out the Sun as the source. Hess had in fact discovered a natural source of high-energy particles: cosmic rays.

Find out more about cosmic rays (from the CERN courier):

Apollo 15 launch

Credit: NASA

Liftoff of Apollo 7

Credit: NASA/The Project Apollo Archive

Liftoff of Apollo 7

Credit: NASA/The Project Apollo Archive

1/2

Credit: NASA

The Last Launch of Space Shuttle Endeavour

Space Shuttle Endeavour has retired from service, and for the moment NASA is reliant on Russian rockets to keep the International Space Station stocked up and operating. NASA is developing a replacement for the Shuttle – the Orion CEV – but for the moment, lets take a look at the Shuttle and remember the many years of sterling service it has given us.

Image credit: Dan Winters

John Glenn's Mercury Suit

Image credit: Dan Winters

John Glenn's Mercury Suit

Image credit: Dan Winters

Space Shuttle Discovery’s Final Launch

Discovery, known as the workhorse of the fleet, is stained and streaked with age. It has flown more missions and carried more crew members than any other shuttle. It was the return-to-flight shuttle after both the Columbia and Challenger disasters.

Image Credit: Dan Winters

Ham the Awesome Astrochimp

On the morning of January 31, 1961, in south Florida, a 5-year-old chimpanzee — dubbed “Ham” by his handlers — ate a breakfast of baby cereal, condensed milk, vitamins and half an egg. Then the unassuming 37-pound primate went out and made aeronautic history: Aboard a NASA space capsule, traveling thousands of miles an hour almost 160 miles above the Earth, he became the first chimp in space.

The success of Ham’s flight helped ratchet up even further the already frantic contest for scientific and space supremacy between the U.S. and the Soviet Union — and briefly made Ham something of a star.

Well before the USSR launched the world’s first artificial satellite, in 1957 — effectively freaking out virtually the entire Western hemisphere — and decades before the U.S. put Armstrong and Aldrin on the moon in 1969, Americans and Soviets used animals to test the rigors and dangers that humans might face in outer space. Mice, rhesus monkeys, dogs — all sorts of creatures blasted off from the surface of the Earth strapped atop rockets and locked in test planes: many suffered injury; not a few of them died.

Ham and his cohorts were picked for the Mercury program over other hominids (gorillas and orangutans) because they’re smaller — and thus could fit in the Mercury capsule — and because, more importantly, “chimpanzees have physical and mental characteristics similar to man,” as LIFE pointed out in its Feb. 10 1961 issue.

The most famous of all the Mercury chimps, due to his landmark January 1961 flight, Ham was actually not publicly called Ham until after the flight succeeded. The name by which he’s now known — an acronym for Holloman Aerospace Medical Center at the Air Force base — was only widely used when he returned safely to earth; NASA reportedly wanted to avoid bad publicity should a named (and thus a known, publicly embraced) animal be killed; all the Mercury chimps were known by numbers.

The astrochimps were not trained to “pilot” space capsules, but instead to perform routine tasks during suborbital flights, and to act, in the most elemental way, as test subjects — facing little-known physical and psychological perils — ahead of their human counterparts in the Mercury program and beyond.

Ham lived at the National Zoo in Washington, D.C, after the flight, then the North Carolina Zoo, where he died at age 26 in 1983. His brief pop culture celebrity (he appeared in a film with Evel Knievel, for example) paled beside the significance of his achievement as NASA’s first astrochimp. A short three months after Ham’s 1961 flight, astronaut Alan Shepard piloted the Mercury capsule on his own historic, 15-minute suborbital space flight, and was feted with ticker tape parades in New York and Washington.

“Alan Shepard was a hero, no doubt about that,” Ralph Morse says today. “But whenever people call Shepard the first American in space, I like to remind them of a chimpanzee who beat him to it.”

Credit: Ben Cosgrove is the Editor of LIFE.com

Apollo 17

Astronaut Eugene A. Cernan.

Credit: NASA

Apollo 17

Astronaut Eugene A. Cernan.

Credit: NASA