Space exploration is not cheap, that’s for sure. Sending a simple probe or satellite into space can cost NASA millions of dollars. It’s even worse if the equipment fails – all that money just goes down the drain. Let’s not forget about all the astronauts living up there for months; how much money does NASA have to spend on all of that? That’s what we’re here to find out. Here are some of the most expensive programs by the National Aeronautics and Space Agency.

1. Space Shuttle Program

Ever since the Space Shuttle Program of the 1970s, a total of five orbiters have been built throughout the project’s five decades of activity. In order, they are: Atlantis, Endeavor, Discovery, Challenger and Columbia. Due to significant mishaps, the last two were destroyed during operations, though the previous missions were highly successful. According to NASA, the entire Space Shuttle Program had over 135 launches and is estimated to cost them between $196 and $206 billion.

2. International Space Station

The International Space Station is the largest artificial object the company has built outside the planet. The operation began in November 1998, when Russia launched the first component called Zarya into space. Two weeks later, the United States followed up with the U.S. Unity node, which was quickly attached to Zarya. The remaining components were then added over the next two years and the first live-aboard crew made their way to the International Space Station on November 2, 2000. The entire project is estimated to cost at least $150 billion.

3. Apollo Space Program

The Apollo Space Program was the famed mission that took three astronauts to the moon. It consisted of a capsule large enough to accommodate up to three astronauts who described it as being the size of a car. They also had a separate craft that transported them from lunar orbit to the surface of the moon and back. But this craft only had enough room for two astronauts, hence why Buzz Aldrin and Neil Armstrong became the first humans to walk on the moon. NASA had to fork out an impressive $110 billion to get everything going. It was totally worth it, though.

4. SLS and Orion

The SLS is NASA’s only rocket powerful enough to send the Orion spacecraft back to the moon for a second time in 53 years. It is set to launch sometime in 2022 and will be the first combined flight of the SLS rocket and the Orion, dubbed Artemis I. Before NASA sends a crewed flight to the moon, they will first test out the craft by sending a crewless Orion spacecraft 40,000 miles further than the moon. If everything goes smoothly, NASA will send an Artemis II mission with astronauts aboard in 2024. So far, this has cost NASA $23 billion.

5. Global Positioning System, Estimated Cost: $12 Billion

The GPS or Global Positioning System, is operated by the U.S. Air Force. It is a space-based radio navigation system that can identify any three-dimensional location to meter-level exactness and time in the world, right down to 10 nanoseconds. The origins of the GPS can be traced back to the Sputnik era, when Russia launched their first satellite. The GPS currently consists of over 30 fully functional satellites, each equipped with a redundant atomic clock and a ground control network that monitors it 24/7. This one is the least expensive of this list: only $12 billion.