Science is often associated with laboratories, microscopes and researchers working with relatively modest equipment.
Some experiments, however, require something much closer to an industrial megaproject.
Humanity has spent billions of dollars—and in some cases hundreds of billions—trying to understand the universe, manipulate matter, explore other worlds and answer questions that cannot be solved inside an ordinary laboratory. From enormous particle accelerators to spacecraft and orbiting laboratories, these projects demonstrate just how expensive the pursuit of knowledge can become.
The definition of an “experiment” can also become surprisingly broad when projects operate for decades, involve thousands of scientists and require international infrastructure. Cost estimates vary depending on whether researchers count construction alone, operations, supporting missions or inflation-adjusted spending. Historical rankings should therefore be treated as approximate rather than definitive.
Here are nine of the most financially ambitious scientific projects ever undertaken.
9. Large Hadron Collider — About $4.75 Billion
Few scientific machines have captured the public imagination like the Large Hadron Collider.
Located near Geneva and operated by CERN, the collider uses a 27-kilometre underground ring to accelerate particles to extraordinary energies before smashing them together. The objective is not simply to create spectacular collisions. Scientists use the resulting debris to investigate the fundamental structure of matter and the forces governing the universe.
The LHC became globally famous in 2012 when researchers announced the discovery of the Higgs boson, providing experimental confirmation of a particle associated with the Higgs field and helping explain why fundamental particles have mass.
The machine itself has been estimated at roughly $4.75 billion in some historical cost assessments.
The scale of the experiment is difficult to comprehend. Scientists are effectively using one of the largest machines ever constructed to investigate particles far smaller than an atom.
More information about CERN and the LHC is available through CERN’s official research programme.
8. Human Genome Project — About $5 Billion
Not every enormous scientific experiment involves rockets or giant machines.
The Human Genome Project attempted something arguably even more ambitious: decoding the genetic blueprint of human life.
Launched in 1990 and completed in 2003, the international project sought to identify and sequence the approximately three billion DNA base pairs that make up the human genome.
The project cost roughly $3 billion in original estimates, although some historical assessments place the overall investment at around $5 billion when broader contributions and associated work are considered.
The scientific payoff extended far beyond producing a sequence.
Understanding the human genome created new possibilities for studying inherited disease, identifying genetic risk factors and developing more personalized approaches to medicine.
The National Human Genome Research Institute provides a detailed history of the project and its scientific achievements.
What makes the Human Genome Project particularly remarkable is that the experiment fundamentally changed the economics of genetic research. Technologies developed during the project helped make DNA sequencing dramatically faster and cheaper.
7. National Ignition Facility — About $3.5 Billion
What happens when scientists try to recreate conditions similar to those inside the Sun?
They build one of the world’s most powerful laser systems.
The National Ignition Facility, located at Lawrence Livermore National Laboratory in California, uses an enormous array of lasers to compress tiny fuel capsules in an attempt to initiate nuclear fusion.
The facility cost approximately $3.5 billion and was designed for research related to fusion, high-energy-density physics and national security.
Fusion is attractive because it has the potential to produce large amounts of energy without the same carbon emissions associated with fossil-fuel combustion.
In December 2022, NIF achieved an important milestone when researchers produced more fusion energy from the target than the laser energy delivered to it. Subsequent experiments produced further ignition results.
The U.S. Department of Energy’s National Ignition Facility programme explains how the facility contributes to fusion and high-energy-density research.
The experiment illustrates an unusual feature of expensive science: even a partial success can transform an entire field.
6. James Webb Space Telescope — Around $10 Billion or More
The James Webb Space Telescope represents one of the most complicated scientific instruments ever sent beyond Earth.
Unlike conventional telescopes that primarily observe visible light, Webb is optimized for infrared observations. That allows scientists to investigate extremely distant galaxies, study the formation of stars and planets and examine atmospheric properties of exoplanets.
Its development became infamous for delays and cost increases.
Historical estimates have placed its total development and launch cost at roughly $10 billion, substantially higher than the project’s original projections. Earlier estimates in some rankings placed the telescope at approximately $12 billion.
The telescope’s scientific value, however, is difficult to measure purely in financial terms.
Webb has provided extraordinarily detailed observations of distant galaxies and star-forming regions, allowing astronomers to investigate parts of cosmic history that were previously inaccessible.
NASA’s official James Webb Space Telescope mission page provides an overview of its scientific objectives and discoveries.
The telescope demonstrates why some experiments cost so much: getting a delicate scientific instrument into space is only part of the challenge. It must also survive launch, deploy successfully and operate millions of kilometres away without physical repair.
5. International Thermonuclear Experimental Reactor — More Than $20 Billion
If nuclear fusion is the ultimate clean-energy experiment, ITER may be its most ambitious test.
The International Thermonuclear Experimental Reactor is being constructed in southern France through a collaboration involving the European Union, China, India, Japan, Russia, South Korea and the United States.
The project is designed to demonstrate the feasibility of producing sustained fusion power using a giant tokamak.
Its cost estimates have increased dramatically over the project’s lifetime. Earlier estimates placed ITER in the $14–18 billion range, while more recent assessments have put the cost at roughly $22 billion.
The machine itself will be enormous, weighing tens of thousands of tonnes.
The basic idea sounds almost impossible: create an extremely hot plasma, confine it using powerful magnetic fields and attempt to generate conditions under which hydrogen isotopes can fuse.
ITER is not intended to become a commercial power plant. Instead, it is designed as a major experimental step toward demonstrating that fusion can be controlled at a scale relevant to future energy systems.
The ITER Organization provides technical information about the machine and its mission.
If successful, the scientific implications could extend far beyond the experiment itself.
4. Manhattan Project — Roughly $23 Billion in Today’s Dollars
Some of the most expensive scientific projects have also been among the most consequential—and disturbing.
The Manhattan Project was the secret U.S.-led wartime programme that developed the first nuclear weapons during World War II.
The project cost approximately $2 billion at the time, equivalent to roughly $23 billion in later inflation-adjusted estimates used by historical rankings.
Scientists, engineers and military personnel worked across multiple locations, with major facilities established at sites including Los Alamos, Oak Ridge and Hanford.
The project culminated in the first nuclear test, Trinity, in July 1945, followed by the use of atomic bombs against Hiroshima and Nagasaki.
The scientific achievement was extraordinary, but its human consequences permanently changed international politics.
The U.S. Department of Energy’s history of the Manhattan Project documents the programme’s scientific and industrial development.
It remains a reminder that scientific capability does not automatically determine whether a discovery will be used for constructive purposes.
3. Apollo Program — Around $110 Billion
Few scientific projects have produced an image as powerful as a human being standing on the Moon.
NASA’s Apollo Program was far more than a single mission. It involved spacecraft development, launch vehicles, navigation systems, life-support technologies, scientific instruments and an enormous industrial infrastructure.
Historical estimates have placed the total cost at around $110 billion in inflation-adjusted dollars.
Apollo 11’s Moon landing in 1969 became one of the defining technological achievements of the 20th century.
Yet the scientific programme continued beyond that first landing. Astronauts collected lunar samples, deployed scientific instruments and conducted experiments that improved understanding of the Moon’s geological history.
The NASA Apollo programme archive provides extensive historical and scientific information about the missions.
Apollo also demonstrated something that enormous scientific experiments often accomplish: they create technologies that spill into other industries.
Computing, communications, materials science and engineering all benefited from the extraordinary technological demands created by the programme.
2. International Space Station — Around $150 Billion
The International Space Station is effectively a laboratory orbiting hundreds of kilometres above Earth.
Its construction began in 1998, and astronauts have continuously occupied the station since 2000. Researchers from multiple countries have used the ISS to study biology, medicine, physics, materials and the effects of microgravity on the human body.
Some historical estimates put its total cost at approximately $150 billion, making it one of the most expensive scientific and engineering projects ever undertaken.
The station’s value comes partly from its longevity.
Unlike a spacecraft that completes a single flyby, the ISS provides scientists with a continuously operating laboratory where experiments can be repeated and modified over many years.
NASA’s International Space Station research programme provides further information about its scientific work.
The ISS is also a remarkable demonstration of international cooperation. Countries that compete geopolitically have nevertheless spent decades operating a shared scientific facility in orbit.
1. Space Shuttle Program — Around $192 Billion
At the top of many historical rankings is NASA’s Space Shuttle Program, which operated from 1981 until 2011.
The programme was intended to create a reusable spacecraft capable of carrying astronauts and cargo into orbit and returning to Earth. Over three decades, the shuttle fleet conducted numerous missions involving satellite deployment, scientific experiments, space-station construction and repairs.
One historical estimate places the total cost at approximately $192 billion in inflation-adjusted dollars.
The shuttle program was eventually retired in 2011 after 135 missions.
Its legacy is complicated.
The reusable spacecraft concept was technologically extraordinary, but the programme proved far more expensive and operationally complex than early visions of inexpensive routine spaceflight suggested.
NASA’s Space Shuttle history provides an extensive record of the vehicles, missions and scientific achievements.
Yet without the shuttle, major elements of modern space infrastructure—including parts of the International Space Station—would have been far more difficult to construct.
The Price of Discovery Keeps Getting Bigger
These projects reveal something fascinating about modern science.
The most difficult questions increasingly require infrastructure on a scale that resembles entire industries.
Understanding the smallest known particles required a 27-kilometre accelerator. Studying the human genome required an international sequencing effort. Investigating fusion requires machines capable of creating extreme temperatures and pressures. Exploring the universe requires telescopes that can operate millions of kilometres from Earth.
And reaching space repeatedly requires launch systems, spacecraft and an enormous supporting industrial network.
The financial figures should therefore not be interpreted simply as money spent on individual experiments. Many of these projects created technologies, scientific communities and datasets that continued producing value long after their original objectives were achieved.
ITER, for example, has already helped develop specialized engineering expertise and supply chains for fusion research even before the experiment reaches its ultimate scientific objectives.
The Most Expensive Experiments Ask the Biggest Questions
There is an obvious temptation to ask whether spending billions—or hundreds of billions—on science is justified.
But the better question may be what humanity receives in return.
Some projects produce immediately practical technologies. Others answer questions that may have no obvious commercial value. Some fail to achieve their original ambitions. Others transform entire scientific disciplines.
The most expensive experiments in history share one characteristic: they attempt to investigate questions that cannot be answered cheaply.
How did the universe begin?
What gives matter mass?
Can humanity reproduce the fusion process that powers stars?
What is the genetic blueprint of human life?
Can humans live and work beyond Earth?
Those questions are expensive precisely because they are difficult.
And as technology advances, the experiments designed to answer them are likely to become even more ambitious.
