HISTORY82 - The Manhattan Project

This summer marks the 78^th anniversary of the development and employment of atomic weapons - events that remain controversial today.  On July 21, 2023, the movie about the chief scientist who was in charge of designing the first bombs, Oppenheimer, was released in the United States, sure to spark renewed discussion about the ethical and moral issues surrounding the effort.  Thus, it seemed to me to be a good time to remind ourselves about the project under which these seminal efforts were conducted, the Manhattan Project.  This article will cover the details of the Manhattan Project.  My next article will focus on life of J. Robert Oppenheimer, sometimes called the “Father of the Atomic Bomb.”

 

After a short introduction, I will discuss the origins of the Manhattan Project, the project’s formation, the choices for type of bomb, the centers of development activity, the extreme secrecy of the program, the test of the first weapon, the decision to drop atomic bombs on Japan, the employment of atomic weapons against Hiroshima and Nagasaki, nuclear weapon development after World War II, and will end with a discussion of the legacies of the Manhattan Project.

My principal sources include: “Manhattan Project,” “Trinity (nuclear test),” “Timeline of the Manhattan Project,” “Timeline of nuclear weapons development,” “Nuclear Weapons of the United States,” and “History of Nuclear Weapons,” Wikipedia.com; “Manhattan Project,” nps.gov; “Manhattan Project,” britannica.com; “Manhattan Project,” history.com; “Manhattan Project,” ahf.nuclearmuseum.org; “The Decision to Drop the Bomb,” ushistory.org; “The Miraculous Deliverance From a Titanic Tragedy,” nationalww2museum.org; “The Pacific War Online Encyclopedia,” pwencycl.kgbudge.com; “Nuclear Weapons: Who Has What at a Glance,” armscontrol.org; plus, numerous other online sources.

Introduction

The Manhattan Project was an unprecedented, top-secret World War II government program in which the United States rushed to develop and deploy the world’s first atomic weapons before Nazi Germany.  It was led by the United States with the support of the United Kingdom and Canada.  From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers.  The nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the bombs. 

The Army component was designated the Manhattan District, as its first headquarters were in Manhattan; that name gradually superseded the official codename, Development of Substitute Materials, for the entire project. 

The Manhattan Project began modestly in 1939, but employed nearly 130,000 people at its peak and cost nearly $2 billion (equivalent to about $30 billion in 2022).  Over 90% of the cost was for building factories and to produce nuclear-reaction capable material, with less than 10% for development and production of the weapons.  Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada.

The first nuclear device ever detonated was the Trinity test, conducted at New Mexico’s newly-named White Sands Proving Grounds on July 16, 1945.  Atomic bombs were then used against Japan’s Hiroshima, August 6, 1945, and Nagasaki on August 9, 1945, after which Japan surrendered, ending World War II.

Origins

In December 1938, scientists in Germany discovered nuclear fission of uranium (the process of breaking large atomic nuclei into smaller atomic nuclei to release a large amount of energy).  Hungarian-born American physicist Leo Szilard realized that nuclear chain reactions could be used to create new and extremely powerful atomic weapons.  In August 1939, Szilard wrote a letter for Albert Einstein to sign and send to President Franklin D. Roosevelt warning that an "extremely powerful bomb" might be constructed.

Albert Einstein and Leo Szilard go over letter to President Roosevelt.

 

Fearing ongoing research and development by Nazi Germany, Roosevelt formed the Advisory Committee on Uranium, a team of scientists and military officials tasked with researching uranium’s potential role as a weapon, which met for the first time on October 21, 1939.  Based on the committee’s findings, the U.S. government started funding research by Enrico Fermi and Leo Szilard at Columbia University, which was focused on nuclear materials and nuclear chain reactions.

The United States formally entered World War II after Imperial Japan bombed Pearl Harbor on December 7, 1941.  With the U.S. now at war, the Advisory Committee on Uranium concluded that an atomic bomb could be designed, built, and used in time to influence the outcome of the war.

Formation of the Manhattan Project

On January 19, 1942, President Franklin Roosevelt authorized the production of an atomic bomb.

The War Department was given joint responsibility with the Office of Scientific Research for the nuclear weapons development, because it was obvious that a vast array of pilot plants, laboratories, and manufacturing facilities would have to be constructed by the U.S. Army Corps of Engineers for military, scientific, and industrial resources to carry out their mission.  On August 13, 1942, the Corps of Engineers’ Manhattan District was formed and assigned the job of creating the atom bomb.  (It was called the Manhattan District because much of the early research had been performed at Columbia University, in Manhattan.)  In September 1942, Brigadier General Leslie R. Groves was placed in charge of all Army activities relating to the project.  “Manhattan Project” became the code name for research work that would extend across the country.

Army Brigadier General Leslie R. Groves was Director of the Manhattan Project.

 

Fermi and Szilard, then at the University of Chicago, were still engaged in research on nuclear chain reactions, the process by which atoms separate and interact, and successfully enriching uranium to produce the isotope uranium-235.

Note: Naturally occurring uranium doesn’t have enough of isotope U-235 necessary to set off a nuclear reaction, but scientists found ways to increase the amount of U-235.

Meanwhile, scientists like Glenn Seaborg were producing microscopic samples of pure plutonium, a man-made radioactive element that was a second candidate to power a nuclear weapon.  And Canadian government and military officials were working on nuclear research at several sites in Canada.

On December 28, 1942, President Roosevelt authorized the formation of the Manhattan Project to combine these various research efforts with the goal of weaponizing nuclear energy. 

The British were also exploring the nuclear weapon problem.  By 1943, a combined policy committee was established with Great Britain and Canada.   In that year, a number of British and Canadian scientists moved to the United States to join the project.

Multiple Paths Forward

The Manhattan Project was immediately faced with a critical problem.   Fissile materials (capable of sustaining a nuclear fission chain reaction) had to be produced and be made suitable for use in an actual weapon.   Scientists theorized there were two potential paths to building an atomic bomb.  One path would use the uranium-235 isotope, which comprises on average less than one percent of naturally occurring uranium. The other path would use the newly discovered element plutonium, which could be created from a controlled chain reaction with uranium.  Both paths required the use of expensive and unproven processes, and success was by no means guaranteed. 

Atom bomb concepts utilizing the two materials were developed.  The uranium-235 bomb utilized a straightforward “gun method” for creating a critical mass and nuclear explosion.  The realization of this design would be called “Little Boy.” 

By 1944, scientists would determine that a gun-type bomb would not work for plutonium.  They turned to the theoretical and extremely complex implosion method.  The realization of this approach would be called “Fat Man.”

The two basic approaches to produce the first atomic bombs.

 

Centers of Operation

The decision was made to move forward with both fissile materials and establish three main sites to support the project.  The project would also involve numerous smaller sites around the nation and the world.

The U.S. Army Corps of Engineers began a nation-wide search for three rural sites that each met distinct criteria.  The federal government then used eminent domain authorities in the Second War Power Act of 1942 to acquire the sites, which displaced Native Americans, farming communities, and homesteaders.  Some only had 30 days to leave and were minimally compensated for their homes.  The three sites were:

Oak Ridge, Tennessee.  Starting in September 1942, a massive industrial complex was built at Oak Ridge, Tennessee, to enrich natural uranium to U-235, and eventually serve as the headquarters of the nationwide project.  Three separate uranium enrichment technologies were pursued in parallel.  A pilot reactor and chemical separation plant were also constructed at Oak Ridge to produce a limited amount of plutonium

Hanford, Washington.  In January 1943, General Groves approved the construction of an enormous industrial complex at Hanford, Washington, for producing plutonium.  The complex had huge production-scale reactors, chemical separations plants, and fuel fabrication facilities.  Despite the speed with which the facilities were engineered and built, production at both the Oak Ridge and Hanford sites was slow and difficult.

Los Alamos, New Mexico.  In April 1943, General Groves began setting up a bomb design and development laboratory at Los Alamos, New Mexico, with some of the world's foremost scientists under the leadership of theoretical physicist J. Robert Oppenheimer.  The laboratory sat atop the Parajito Plateau in an isolated area in northern New Mexico, 34 miles north of Santa Fe. 

Theoretical physicist J. Robert Oppenheimer was director of Los Alamos Laboratory that developed the first nuclear weapons.

 

This laboratory was tasked with developing methods to reduce the fissionable products from the production plants to pure metal and fabricate the metal to required shapes.  Methods of rapidly bringing together amounts of fissionable material to achieve a supercritical mass (and thus a nuclear explosion) had to be devised, along with the actual construction of a deliverable weapon that would be dropped from a plane and fused to detonate at the proper altitude above the target.  Most of these problems had to be solved before any appreciable amount of fissionable material could be produced, so that the first adequate amounts could be used at the fighting front with minimum delay.

Note:  Before 1943, work on the design and functioning of the bomb itself was largely theoretical, based on fundamental experiments carried out at a number of different locations.  Building the bombs themselves was not an easy task.  Precise calculations and countless hours of experimentation were required to obtain the optimum specifications of size and shape. 

The three principal centers for atomic bomb development.  Oak ridge supplied enriched uranium and Hanford supplied plutonium to the bomb development site at Los Alamos.

 

The Manhattan Project contracted private firms and corporations to build and manage the communities built to house the Manhattan Project workers.  Each community became a beehive of activity that boasted of theaters, stores, schools, hospitals, parks, and local gathering places.  By 1945, Oak Ridge’s population had soared to about 75,000.  Richland, a bedroom community for the Hanford site, saw its population climb to 15,000, while Los Alamos' population reached 6,000.

Secrecy

The Manhattan Project was the best-kept secret of World War II.  More than 100,000 people employed with the project "worked like moles in the dark.”  Warned that disclosing the project's secrets was punishable by 10 years in prison or a fine of $10,000 (equivalent to $163,000 in 2022), workers saw enormous quantities of raw materials enter factories with nothing coming out, and monitored "dials and switches while behind thick concrete walls, mysterious reactions took place," without knowing the purpose of their jobs.

The Manhattan Project was "more drastically guarded than any other highly secret war development.”  The security infrastructure surrounding the Manhattan Project was so vast and thorough that in the early days of the project in 1943, security investigators vetted security risks of 400,000 potential employees and 600 companies that would be involved in all aspects of the project.  

Billboard at one of the fissile material production sites encouraging secrecy among the workers.

 

Voluntary censorship of atomic information began before the Manhattan Project.  After the start of the European war in 1939, American scientists began avoiding publishing military-related research, and in 1940, scientific journals began asking the National Academy of Sciences to clear articles. 

The prospect of sabotage was always present, and sometimes suspected, when there were equipment failures.  While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage.

By 1943, it was clear that the Soviet Union was attempting to penetrate the project.  The most successful Soviet spy was Klaus Fuchs, a member of the British Mission who played an important part at Los Alamos.  The 1950 revelation of his espionage activities damaged the United States' nuclear cooperation with Britain and Canada.  Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass, and Julius and Ethel Rosenberg.  The value of the espionage is difficult to quantify, as the principal constraint on the Soviet atomic bomb project was a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort to produce an atomic bomb.

Note:  Julius and Ethel Rosenberg were tried and executed for spying; Fuchs, Gold, and Greenglass received prison sentences.

Trinity Test

It was not until mid-1945 that enough enriched uranium and plutonium were available for construction of the first atomic bombs.

As planned, scientists working under Oppenheimer had developed two distinct types of bombs: a uranium-based design called “Little Boy” and a plutonium-based weapon called “Fat Man.”

Uncertain that it would work, officials decided to test the plutonium device.  Such a test was no simple affair.  Elaborate and complex equipment had to be assembled to provide a complete diagnosis of success or failure. 

 

The “gadget” was the nickname given to the first atomic bomb to be tested.

The first atomic bomb was exploded at 5:30 am on July 16, 1945, in the Jornada del Muerto desert, about 35 miles southeast of Socorro, New Mexico, within the newly-named White Sands Proving Grounds.  Oppenheimer had called the site “Trinity” in reference to one of John Donne’s Holy Sonnets. 

The bomb - a plutonium implosion device nicknamed the Gadget, of the same design as the Fat Man bomb concept - was raised to the top of a 100-foot steel tower. 

The area at the base of the tower was marked as “Ground Zero,” a term that would pass into common parlance to describe the center of an (often catastrophic) event.  The tower was surrounded by scientific equipment, with remote monitoring taking place in bunkers occupied by scientists and a few dignitaries 10,000 yards away. 

The Trinity-test atom bomb was set atop this 100-foot tower.

 

The explosion came as an intense light flash, a sudden wave of heat, and later a tremendous roar as the shock wave passed and echoed in the valley.  A ball of fire rose rapidly, followed by a mushroom cloud extending to 40,000 feet.  The bomb generated an explosive power equivalent to 15,000 to 20,000 tons (15 - 20 kilotons) of TNT; the tower was completely vaporized and the surrounding desert surface fused to glass for a radius of 800 yards.

The first atomic bomb was exploded at 5:30 am on July 16, 1945, ushering in the nuclear age.

 

Note: The largest non-nuclear man-caused explosion to date occurred in 1916 when 200 tons of TNT exploded in a gunpowder mill in Kent England.  The Trinity test was 75 to 100 times more powerful than this.

The Decision to Use Atomic Bombs on Japan

In just a few short years, the Manhattan Project succeeded in its mission to create the world’s first atomic weapons. 

Yet, as the project moved closer to the use of the first atomic bomb, ethical questions arose in the minds of some who understood the project’s intent.  Scientists and politicians, however, were primarily concerned with ending the war as quickly as possible.  On May 8, 1945, Germany unconditionally surrendered to the Allies, ending World War II in Europe.  With Germany out of the war, the Allies turned their full attention to the war in the Pacific.

Note: The German effort to build an atomic bomb started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but proceeded sporatically due to inefficient organization, other wartime priorities, and lack of available scientific personnel.  Ultimately the German atomic program became "frozen at the laboratory level."   Despite U.S. fears at the time, the Germans had never been close to producing nuclear weapons. 

 When U.S. President Harry Truman (who had become U.S. president on April 12 1945 upon Franklin’s Roosevelt’s death) learned of the success of the Manhattan Project, he knew he was faced with a decision of unprecedented gravity.  The capacity to end the war with Japan was in his hands, but it would involve unleashing the most terrible weapon ever known.

Note:  Japan had been at war in Pacific since the 1930s, seeking to expand its empire, and responsible for an enormous (and little known) loss of life:  The Second Sino-Japanese War commenced in July 1937 when China began sustained resistance to Japanese aggression, and was still being fought in 1945.  More than midway through the Second Sino-Japanese War, on December 7, 1941, the Japanese simultaneously attacked American military bases in Hawaii, Wake Island, Guam, and the Philippines, and invaded Thailand and the British colonies of Malaya, Singapore, and Hong Kong, initiating the Pacific Theater War of World War II.

By the summer of 1945, conservative accounting shows that 25 million people died in the Second Sino-Japanese War.  About six million were combatants, mostly Chinese and Japanese.  There were also 18 million non-Japanese noncombatant deaths.  

The Pacific Theater War, the World War II struggle between the United States and it allies with Japan across the Pacific, produced about 2 - 2.5 million additional deaths by the summer of 1945.  By then, the United States had suffered over 110,000 deaths, with over 250,000 wounded, and over 21,000 prisoners of war.

Following the successful atomic test on July 16^th, on July 26^th, at the Potsdam Conference in the Allied-occupied city of Potsdam, Germany, the U.S. made a demand for an immediate unconditional surrender to the leadership in Japan.  Although the demand stated that refusal would result in total destruction, the Japanese military command rejected the request for unconditional surrender.

American soldiers and civilians were weary from four years of war, yet the Japanese military was refusing to give up the fight.  American forces occupied Okinawa and Iwo Jima, and were intensely firebombing Japanese cities.  But Japan had an army of two million strong stationed in the home islands guarding against invasion.

The consensus among U.S. military leaders in 1945 was that the Japanese would fight to the bitter end, and force a full-scale invasion of the island nation, resulting in significant casualties on both sides.

President Truman rejected a demonstration of the atomic bomb to the Japanese leadership.  He knew there was no guarantee the Japanese would surrender if the test succeeded, and he felt that a failed demonstration would be worse than none at all. 

President Harry S. Truman authorized the first and only use of atomic weapons in combat.

 

President Truman later stated that his decision to drop the bomb was purely military.  A Normandy-type amphibious landing would have cost an estimated million American casualties.  Truman believed that the bombs saved Japanese lives as well.  Prolonging the war was not an option for the President. 

Hiroshima and Nagasaki

The United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki.   Until that point, neither city had been attacked during the U.S. strategic bombing campaign; planners wished to demonstrate the destructive power of the bombs.  A forceful demonstration of the technology developed in New Mexico was deemed necessary to encourage the Japanese to surrender.

The U.S. dropped atoms bombs on Hiroshima and Nagasaki.

 

Hiroshima.  Hiroshima was selected as the primary target because of its military value; the city served as the headquarters of the Japanese Second Army.  Moreover, there were no known American prisoners of war in the area.  On August 6, 1945, at about 8:15 am local time, the U.S. Enola Gay B-29 bomber released the as-yet untested gun assembly fission bomb - dubbed Little Boy - above Hiroshima. The weapon detonated at an altitude of 1,900 feet, and the explosive yield was estimated to be the equivalent of 15,000 tons of TNT.  Some 70,000 people were killed instantly, and by the end of the year the death toll had surpassed 100,000.  Five square miles, two-thirds of the city area, was destroyed.

 

Hiroshima after the first atom bomb strike.

Nagasaki.  By the morning of August 9, 1945, the Soviet Union had declared war on Japan, but the Japanese government had not yet communicated its intent to surrender to the Allies.  Another B-29, carrying Fat Man - a plutonium implosion bomb similar to the one used in the Trinity test - dropped the bomb over the port city of Nagasaki, site of a torpedo-building plant.  At 11:02 am local time Fat Man exploded at an altitude of 1,650 feet northwest of the city center.  The bomb detonated with the explosive force of 21,000 tons of TNT.  An estimated 40,000 people were killed instantly, and at least 30,000 more would die from their injuries and radiation poisoning by the end of the year.  About three square miles, or 40% of the city’s buildings were completely destroyed or severely damaged.  Due to the area’s uneven terrain, a significant part of Nagasaki - particularly in the southeastern industrial and government district - was relatively unscathed.

Nagasaki after the second atom bomb strike.

 

On August 10^th, the Japanese informed Washington, of their intention to surrender, and formally surrendered on August 14, 1945.  The Japan signed the Instrument of Surrender on September 2, 1945, on the deck of the USS Missouri, officially ending the most deadly and destructive war in human history.

After the War

In 1946, the Manhattan Project oversaw Operation Crossroads, a military-scientific experiment conducted at Bikini atoll in the South Pacific. 

Two peacetime atomic weapons tests were carried out.  In the first test in July, a 20-kiloton atomic bomb was dropped from a B-29 and exploded at an altitude of about 520 feet over a fleet of about 80 decommissioned World War II naval vessels.  In the second test in August, a 23-kiloton device was suspended at a depth of 90 feet from a decommissioned landing craft in the Bikini lagoon.  Important information on nuclear damage effects and radioactivity was obtained.

Following these tests and a domestic debate over the permanent management of the nuclear program, the United States Atomic Energy Commission (AEC) was created by the Atomic Energy Act of 1946.  Under the AEC, atomic weapon development and testing continued along with development of the peaceful uses of atomic energy. 

The Atomic Energy Act separated the development, production, and control of atomic weapons from the military.  The Manhattan Project ceased to exist on December 31, 1946, with the AEC taking over the functions and assets of the Manhattan Project, including direction of the plants and laboratories under its jurisdiction.  Military aspects of atomic weapons were taken over by the Armed Forces Special Weapons Project (AFSWP); General Leslie R. Groves, the former head of the Manhattan Project, was its first chief.  In 1959, the AFSWP became the Defense Atomic Support Agency, a field agency of the Department of Defense.

The U.S. government disbanded the AEC under the Energy Reorganization Act of 1974, and divided its functions between two new agencies: the Nuclear Regulatory Commission (1974), which regulates the nuclear power industry, and the Department of Energy (1977) which maintains nuclear weapon responsibilities through the National Nuclear Security Administration.  Some functions were taken over or shared by the Department of Homeland Security in 2002.

Legacies of the Manhattan Project

The political and cultural impacts of the Manhattan Project were profound and far-reaching. 

Continued Nuclear Arms Development and Proliferation.  The use of nuclear weapons in the Second World War led to a nuclear arms race between the U.S. and the Soviet Union.  In 1949, the Soviet Union conducted it first test of a fission atomic bomb.  In 1952, the U.S. conducted the first test of a thermonuclear hydrogen bomb, a second-generation nuclear weapon employing nuclear fusion technology, with a yield of 10.4 megatons of TNT, almost 700 times more powerful than the bomb dropped on Hiroshima.  Only one year later, in 1953, the Soviet Union conducted their first test of a hydrogen bomb. 

Nuclear Warhead Standardization and Miniaturization. The original Little Boy and Fat Man weapons, developed by the United States during the Manhattan Project, were relatively large (Fat Man had a diameter of five feet and heavy (around five tons each), and required specially modified bombers to be adapted for their bombing missions against Japan.  Each modified bomber could only carry one such weapon, and only within a limited range.  After these initial weapons were developed, a considerable amount of money and research was conducted towards the goal of standardizing nuclear warheads so that they did not require highly specialized experts to assemble them before use, and miniaturizing the warheads for use in more variable delivery systems.

Development of delivery systems for atomic warheads proceeded steadily.  Improvement of long-range bombers continued.  During the 1950s and 1960s, intercontinental ballistic missile systems were developed that could deliver a nuclear payload across vast distances.  Shorter-range weapons, including small tactical weapons, were fielded in Europe as well, including nuclear artillery and the man-portable Special Atomic Demolition Munition.  The development of submarine-launched ballistic missile systems allowed for hidden nuclear submarines to covertly launch missiles at distant targets as well.  Improvements in warhead miniaturization in the 1970s and 1980s allowed for the development of missiles which could carry multiple warheads, each of which could be separately targeted.  Additional developments in weapons delivery included cruise missile systems, which allowed a plane to fire a long-distance, low-flying nuclear-armed missile towards a target from a relatively comfortable distance.

 

Miniaturization of nuclear weapons between 1945 - 1986.

Nuclear Proliferation. At the dawn of the nuclear age, the United States hoped to maintain a monopoly on its new weapon, but the secrets and the technology for building the atomic bomb soon spread.

Other countries besides the U.S. and the Soviet Union soon joined the nuclear community, including the United Kingdom (1952), France (1960), and China (1964).  Seeking to prevent the nuclear weapon ranks from expanding further, the United States and other like-minded countries negotiated the nuclear Nonproliferation Treaty (NPT) in 1968 and the Comprehensive Nuclear Test Ban Treaty in 1996.

India, Israel, and Pakistan never signed the NPT and possess nuclear arsenals.  Iraq initiated a secret nuclear program under Saddam Hussein before the 1991 Persian Gulf War.  North Korea announced its withdrawal from the NPT in January 2003, and has successfully tested advanced nuclear devices since that time.  Iran and Libya have pursued secret nuclear activities in violation of the treaty’s terms, and Syria is suspected of having done the same. 

At the time the NPT was concluded, the nuclear stockpiles of both the United States and the Soviet Union/Russia numbered in the tens of thousands.  Beginning in the 1970s, U.S. and Soviet/Russian leaders negotiated a series of bilateral arms control agreements and initiatives that limited, and later helped to reduce, the size of their nuclear arsenals. 

Bilateral discussions continue towards significant reductions in nuclear warhead inventories.

Nuclear warhead inventories by country.

 

Concerns about Nuclear Weapon Accidents and Terrorism.  Since 1950, there have been 32 nuclear weapon accidents, defined as an unexpected event involving nuclear weapons that result in the accidental launching, firing, detonating, theft, or loss of the weapon.  To date, six nuclear weapons have been lost and never recovered.

The fear of a nuclear apocalypse at the hands of terrorists has been amplified in the media, in movies and novels, and by political leaders’ statements since 9/11.  Such an attack could take the form of the detonation of a complete nuclear weapon or the dispersal of radioactive material.  Thankfully, a terrorist nuclear attack has not occurred to date. 

National Laboratories.  The wartime Manhattan Project left a legacy in the form of the network of national laboratories: the Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory, Argonne National Laboratory, and Ames Laboratory.  Two more were established by General Groves soon after the war, the Brookhaven National Laboratory at Upton, New York, and the Sandia National Laboratories at Albuquerque, New Mexico.

Peaceful Uses of Atomic Energy. The nuclear fission technology perfected by the Manhattan Project engineers has since become the basis for the development greatly improved nuclear reactors.  The ability of the new reactors to create radioactive isotopes in previously unheard-of quantities sparked a revolution the civilian world.  In the U.S., 20% of electricity is supplied by nuclear energy.  Nuclear imaging technology can diagnose and treat cancer and other diseases. Space exploration vehicles use radioactive power systems.  Nuclear technology enhances agricultural productivity and helps detect animal diseases.  Nuclear technology enhances criminal investigation through identification of trace materials.  Nuclear technology helps scientists understand and address environmental issues like climate change.  It can also help trace pollution in marine waters and combat ocean acidification.

Manhattan Project Museum.  In 2014, the United States Congress passed a law providing for a national park dedicated to the history of the Manhattan Project. The Manhattan Project National Historical Park was established on 10 November 2015, at the three principal weapon development sites:  Hanover, Oak Ridge, and Los Alamos.  The new park works to interpret the Manhattan Project’s history and legacy for our world today.

 

The use of nuclear weapons by the United States against Japan ultimately became one of the most important historical events of the 20^th century.  The project ushered in the nuclear age and raised ethical and moral questions among scientists and citizens alike - questions that continue to this day.