Computers in Space! How Microchips and Code Unlocked the Stars

CIMSA computer for the Spacelab

Computers in Space! How Microchips and Code Unlocked the Stars

Key Points:
  1. Computers in space are designed with error correction and fallbacks as a priority.
  2. The Gemini Project was the first spacecraft to have a digital computer onboard.
  3. IBM led the development of the first computers in space.
  4. Space computers can autonomously launch, control, and land spacecraft.
  5. Most computers in space distribute heavy calculations to computers on the ground.

Space travel would be impossible without computers. Plus, advancements in computing technology and the space race have always gone hand in hand, with each field spurring the other’s success. But how did we get from the massive mainframe computers of the 1950s and 1960s to the small computers we use in space now? The most common computer at the time of NASA’s founding was the UNIVAC, a colossal piece of equipment that needed a team of people to manage it. Within a few decades, we went from room-sized computers like the UNIVAC, to the single miniature computers we know today.

Computers are now vital for every kind of spacecraft. From manned to unmanned missions, computers play an integral role in handling system management, data formatting, and altitude control. Additionally, computers handle critical system functions like navigation and mid-course corrections. Let’s explore how we went from earth-bound computers like the UNIVAC, to the computers in space we have today.

Apollo display and keyboard unit.
Apollo Guidance Computer provided computation and electronic interfaces for navigation, guidance, and spacecraft.

©NASA / Dennis Taylor, Public domain, via Wikimedia Commons – License

The Challenges of Computers in Space

With computers in space, you face several difficulties that make them operate differently. While computers on earth can get by with the user sitting in front of them, controlling everything, and telling the software what to do, computers in space are different. The challenge with computers in space is that users can’t always be there to type in commands or operate the software.

Additionally, computers in space must operate in “real-time” mode as opposed to “batch” mode. While our earthly computers typically process data in chunks or batches as it is loaded from memory, computers in space can’t do this. With advanced computational scenarios such as landing a space shuttle or correcting course mid-flight, batch processing would cause disaster. By the time a batch of input is grouped and processed, the situation could have changed drastically. For this reason, real-time processing is of paramount importance.

Since the user can’t always manage the computer onboard a spacecraft, the hardware and software must be “failure-proof.” Even on manned spacecraft, a computer failure could spell disaster. NASA engineers get around this by making as many redundant systems as possible. In other words, when one system fails, another takes its place.

How do Computers in Space Work?


Computers in space work by prioritizing redundancy. This means that if one system fails, another is there to take its place. Due to the communications delay of roughly 1.5 seconds between ground control computers and computers in orbit, systems must be able to operate in real-time, with little input from ground control.

NASA often installs three or four backup systems for each process handled by onboard computers. In the event of critical system failure, another system will always be present to take over and avert a crisis.

Distributed Processing

Since early spacecraft simply couldn’t handle the weight of advanced computing systems, which often weighed hundreds or thousands of pounds, only lightweight computers were installed onboard. These computers sent complex calculations to ground-based computers, returning the results. Distributing processing power across multiple systems allows spacecraft to save precious weight using lighter computers.

Distributed processing is of importance when it comes to unmanned spacecraft such as space probes. Missions like Galileo and Voyager, probes that would journey beyond the solar system, relied heavily on distributed processing systems.

NASA emblem at the Kennedy Space Center Visitor Complex

NASA was initially reluctant to use new languages like FORTRAN in early missions and instead relied on machine language.

©CrackerClips Stock Media/Shutterstock.com

Proven Equipment

Since computers in space must be completely error-free and operate with a high-fault tolerance, only proven equipment is used. This explains why NASA was initially reluctant to use new languages like FORTRAN in early missions and instead relied on machine language. 

This also explains why modern spacecraft rely on systems from manufacturers like Lenovo. The Lenovo ThinkPad is used throughout the space station and on manned space flights due to its robust design and tried-and-true technology. In addition, the ThinkPad also has the military-grade durability required for space travel.

Gemini: The First Computer in Space

After Project Mercury, the first man in space effort from the United States, it became clear that having an onboard computer would be vital to the success of future missions. An onboard computer would be able to assist with things like prelaunch, ascent, rendezvous, and re-entry calculations. Additionally, a computer would give the astronauts more time to perform experiments without worrying about controlling the spacecraft.

The Gemini was the first mission to have a digital computer onboard. Designed by none other than IBM, the Gemini computer was entirely custom-fabricated for NASA’s specifications. IBM put its finest engineers on the front lines to develop the Gemini computer starting in 1962, and by 1965 they had delivered the finished product.

Although the Gemini was a marvel of engineering at the time, it lacked the redundancy and fail-safes of future space-bound computers. This made it less than ideal for fully automating space flight, and to combat this, astronauts on board could step in and take control when the computer had an error.

Using a unique type of memory called “Ferrite Core Memory” the Gemini Computer could store tiny amounts of data and perform basic calculations. Additionally, the processor worked in a serial format, meaning it processed just one bit at a time. This may be snail pace by today’s standards, but some clever engineering made it extremely capable.

Ferrite core memory
A sample of old Ferrite core memory that was possibly used in spacecraft. This piece dates from the 1960s.


Early Software in Space

Besides being the first craft to bring a digital computer into space, the Gemini project brought with it innovations in software. IBM’s continuous development of software for the Gemini project led to the birth of concepts still used to this day. Practices like error detection and built-in diagnostics are commonplace in technology now, and we have Gemini’s digital computer to thank for this.

Early software programs were often not completely understood. Because of a complete lack of software methodologies, the program development were haphazard and disorganized. NASA’s need to use proven technology meant newer languages like FORTRAN were frowned upon. Although FORTRAN is regarded as one of the earliest programming languages today, it was in its infancy and couldn’t be trusted by NASA engineers. The alternative was machine language, more commonly known as “assembly” language today.

Additionally, the reliability of early software was also an issue for use in spacecraft. NASA sought to improve upon this immediately. The most common format for loading software programs was with a magnetic tape drive. Although tape drives were not the most reliable format, NASA improved upon the standard design and implemented their own “hardened” version. Tape drives made by NASA were tested to be able to withstand massive amounts of vibration and radiation. 

Computers On the Apollo Mission

Early advances in the Gemini project led to a headstart on the Apollo project. Well known for bringing man to the moon, the Apollo project was already gifted with a robust hardware and software foundation. Navigating to the moon was no easy task. It became clear that NASA needed to upgrade its computer equipment for the new mission.

The computer onboard the Apollo missions was referred to as the “fourth crew member” because it played a key role in navigating the spacecraft. To develop the most robust system, NASA contracted MIT to develop the technology. In 1961, MIT officially began the development of the Apollo mission’s computer systems

The hardware and software development for the mission was plagued with setbacks and difficulties. Due to constantly evolving requirements, each Apollo mission from 1961 until the Moon Landing in 1969 used a more powerful system than the last. By the time the famous Apollo 11 mission came around, the onboard computers from the earliest missions were unrecognizable.

Additionally, the onboard computers handled a long list of tasks. With 4K of RAM and 32K of storage capacity, the Apollo computer made fantastic use of relatively weak hardware. Although computers today are vastly more powerful, the Apollo computer could control a variety of tasks even with limited hardware. Even more impressive is that the onboard computer controlled the Saturn booster, targeting, altitude control, autopilot, and all controls related to velocity changes with very little human input.

Computers in Space Today

Today, computers are vital l to space exploration than ever before. The main focus, going into the future, is making affordable computers that can handle more complex calculations. Historically, the cost of developing spacecraft computer systems has been prohibitively high. Reducing the cost of development and operation is crucial to ensuring continued progress on research in space. 

Companies like SpaceX and Blue Origin are building on decades of research done by NASA engineers. Besides reducing costs and improving computational performance, there are a few key areas where computers help us unlock the stars.


One area where space computers are evolving is satellite technology. Communication satellites have been operational for decades, but their full potential is now becoming a reality with advancements in satellite technology.

Leveraging advances in artificial intelligence and machine learning, supercomputers on earth can use satellites to broaden our knowledge of our planet. Satellites are useful in mineral deposit extraction, agriculture development, and disaster mitigation. Additionally, satellites help gather weather and climate data for research and simulation.

Communication satellite orbiting space above the Earth.

An area where the usage of space computers is growing is in the advancement of satellite technology .



Telescopes were first launched into space in the 1970s to observe our universe. Without computers, these telescopes wouldn’t be able to navigate, process images, or communicate with ground control.

The onboard computer in many space telescopes works similarly to any unmanned spacecraft, but with a few key differences. Telescopes have extra software for calibrating the mirror and image processing hardware. Additionally, the onboard computers store images and relay them back to Earth.

Planetary Rovers

Since the early lunar missions, planetary scientists have been using rovers to study the moon and planets. Essentially, rovers are remote-controlled robots with various onboard computer systems that help the rover function autonomously.

The Curiosity Rover explored the surface of Mars in 2012 with the help of a specially designed onboard computer: PowerPC RAD750 CPU. It’s significantly slower than a typical desktop computer. However, this computer can withstand the extreme heat and radiation found on the surface of Mars. Future planetary rovers will likely become more powerful.

The future is being led by the desire to colonize Mars. Companies like SpaceX, led by Elon Musk, are at the forefront of spearheading Mars colonization. If the past is any indication of the future, we can expect computers to play a pivotal role in our expansion into the universe.

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Frequently Asked Questions

Do computers work in space? 

Computers work in space, albeit a little differently than they do here on Earth. Computers must be designed to withstand enormous forces, low gravity, and the radiation of space. Through generations of improvements and iterations, the computers used in space today have been tried and tested to work reliably.

What was the first computer in space?

The Gemini Project was responsible for bringing the first computer to space in 1965.

How much memory did the Apollo mission computer have?

The computer onboard the Apollo spacecraft had the equivalent of 32K of memory.

Has any computer in space ever been hacked?

There have been occurrences of cyber attacks on satellites in the past. However, there have been no recorded instances when manned spacecraft were compromised. In recent years, there have been cyber attacks on ground control computers, most notably the Johnson Space Center in 2018.

What computers does NASA use?

NASA uses a variety of workstations and servers made by Dell, HP, and IBM in their ground control computers. In the space shuttle, the most commonly used computer is the Lenovo ThinkPad due to its military-grade construction.

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