The most expensive science project ever built is the International Space Station, which has been described as the most expensive single item ever constructed, with a total cost of about $150 billion as of 2010. Next comes the Apollo program at $25 billion in the money of the day, then the ITER fusion reactor in France, projected at up to €22 billion and climbing. This list ranks ten science experiments and instruments by what they cost, as of October 2026, and notes the basis of each figure, because a 1960s dollar and a 2020s euro do not sit on the same scale.
The old version of this page listed things like a $15 million quantum computer. The numbers here are bigger, and every one is a published project cost or a published estimate.
| Rank | Project | Cost as reported | Basis |
|---|---|---|---|
| 1 | International Space Station | $150 billion | Total cost as of 2010 |
| 2 | Apollo program | $25 billion (about $187 billion today) | Peacetime cost, 1960s to 1970s |
| 3 | ITER fusion reactor | €18 billion to €22 billion | Projected total, France |
| 4 | Manhattan Project | Nearly $2 billion (about $28 billion today) | 1940s |
| 5 | Hubble Space Telescope | About $11.3 billion | Cumulative, in 2015 dollars |
| 6 | James Webb Space Telescope | $10 billion | Total cost |
| 7 | Large Hadron Collider | About $9 billion | Budget cited in 2010 |
| 8 | Human Genome Project | About $2.7 billion | Final cost, 1990 to 2003 |
| 9 | Square Kilometre Array | €1.8 billion | 2014 estimate |
| 10 | LIGO | $620 million | Total after 2015 overhaul |
1. International Space Station: $150 billion
The station has been described as the most expensive single item ever constructed. The total of $150 billion as of 2010 includes NASA’s $58.7 billion budget for 1985 to 2015, Russia’s $12 billion, Europe’s $5 billion, Japan’s $5 billion, Canada’s $2 billion and the cost of 36 shuttle flights to build it. The science runs from Earth observation to astronomy. We take the 2010 total as given, so the real figure today is higher.
2. Apollo program: $25 billion in its day
Landing people on the Moon by the end of 1969 meant the largest commitment of resources ever made by any nation in peacetime. The bill was $25 billion, which is roughly $187 billion once adjusted to 2024. At its peak the program employed 400,000 people and relied on over 20,000 firms and universities. It sits second only because the ISS number is a cumulative one.
3. ITER: €18 to €22 billion
The fusion reactor under construction at Cadarache in France was meant to cost about €5 billion. The projected total for construction and operations is now put at between €18 billion and €22 billion, and other estimates put it between $45 billion and $65 billion, which ITER disputes. A schedule announced in July 2024 pushes the start of research operation to 2034 and deuterium-tritium operations to 2039. Seven parties pay for it: China, the EU, India, Japan, Russia, South Korea and the US.
4. Manhattan Project: nearly $2 billion
The wartime program that produced the first nuclear weapons employed nearly 130,000 people at its peak and cost nearly $2 billion, roughly $28 billion adjusted to 2024. More than 80 percent went on the plants that made fissile material.
5. Hubble Space Telescope: about $11.3 billion
Hubble was first estimated at $300 million. By launch in 1990 it cost about four times that, and with servicing missions the cumulative cost is estimated at about $11.3 billion in 2015 dollars, not counting operations. By that measure it was the most expensive science mission when launched.
6. James Webb Space Telescope: $10 billion
Webb began life as a $1 billion idea with a launch around 2007. A big redesign in 2005, construction that finished in 2016 and years of testing brought the total to $10 billion.
7. Large Hadron Collider: about $9 billion
CERN’s accelerator was budgeted at about €7.5 billion, or $9 billion, when counting everything, as cited in 2010. The core accelerator was put at 4.6 billion Swiss francs, plus about 1.16 billion for the experiments. It was approved in 1995 with a budget of 2.6 billion francs, and overruns pushed that up. The collider began another run in July 2022, and a long shutdown from 2026 to 2030 is meant to upgrade it for higher luminosity.
8. Human Genome Project: about $2.7 billion
The project to map the human genome was set up in 1990 with a $3 billion budget and was expected to take 15 years. It ended up costing less than expected, at about $2.7 billion. A private rival, Celera, planned a similar effort for $300 million.
9. Square Kilometre Array: €1.8 billion
The radio telescope array in Australia and South Africa was estimated at €1.8 billion in 2014, including €650 million for its first phase. The project has seen repeated delays and rising costs over nearly 30 years, so the final bill will likely be higher.
10. LIGO: $620 million
The gravitational-wave observatory finished a five-year, $200 million overhaul in 2015 that brought its total cost to $620 million. Months later, it announced the detection of gravitational waves from two black holes merging 1.3 billion light-years away.
Records set in 2025 and 2026
- December 2025: private donors, including Yuri Milner, Eric Schmidt, John Elkann and Xavier Niel, pledged €860 million (about $1 billion) toward CERN’s future collider plans. The hadron-collider version of that proposal, FCC-hh, is projected to cost over $20 billion.
- 2026: the LHC’s third run was scheduled to run until 2026, with a long shutdown for upgrades planned for 2026 to 2030.
- ITER’s July 2024 schedule reset remains the latest official timetable we found.
What drives these prices
- Scale. Every project here needed a purpose-built machine, a launch or a tunnel.
- Delay. Hubble, Webb and ITER all cost several times their first estimates.
- International pooling. The biggest projects are paid for by many countries, which also makes costs harder to pin down.
- One-offs. None of these can be bought off a shelf, so there is no market price to anchor a budget.
FAQ
FAQ
What is the most expensive science experiment ever?
The International Space Station, with a total cost of about $150 billion as of 2010. Apollo cost about $25 billion at the time.
How much did the Large Hadron Collider cost?
About $9 billion when everything is counted, as cited in 2010. The accelerator itself was put at about 4.6 billion Swiss francs.
How much will ITER cost?
The projected total for construction and operations is €18 to €22 billion, though other estimates run to $45 to $65 billion.
How much did the James Webb Space Telescope cost?
About $10 billion in total.
Why do big science projects go over budget?
They are one-offs with new technology, built by many countries, so delays and redesigns compound. Webb started as a $1 billion idea and Hubble’s cost grew about fourfold before launch.
How we put this list together
We ranked science projects by published total costs and estimates, compiled in an internal valuation model. Figures use different years and currencies, so they are approximate and change over time.
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Last updated: October 2026.
