Space travel does not always require warp-speed innovation

How powerful were the Apollo computers?

Would you travel to the moon in a vessel equipped only with a Radio Shack TRS-80 computer or a Commodore VIC-20?

The astronauts of the Apollo missions used computer technology that's primitive by today's standards. But as our reach and power into space have expanded — think probes to distant planets, space telescopes, the space shuttle program and the International Space Station — remnants of the old technologies are still in use.

"To this day, NASA still uses elements of technology that powered the moon landings of the 1960s and 1970s, while the International Space Station — the manned station circling the Earth 250 miles above our heads — relies on processors dating back more than two decades," writes Nick Heath at

The space shuttle program has seen only one major upgrade to its avionics computer technology since the program's inception in the 1970s, Heath adds.

Alessandro Donati, head of the Advanced Mission Concepts and Technologies Office at the European Space Agency's Space Operations Centre in Darmstadt, Germany, told Heath that the important factor for space exploration IT is reliability, not innovation.

"In aerospace, you don't fly the cutting-edge technology that is being used on the ground by business," Donati said.

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Look at how primitive this seems, and recall that the Apollo program used computers developed 15 or 20 years earlier.

The computer that provided flight guidance for the Apollo missions was so simple that a hobbyist can now build one at home, according to a design from John Pultorak.

The Apollo guidance computer pales in comparison to even the first-generation IBM PC, which at 8K had four times as much memory and a processor that ran at 4.077 MHz, compared with the Apollo computer's 1.024 MHz, writes Grant Robertson at

"The real-time operating system in the Apollo 11 spacecraft could multitask eight jobs at a time, no small feat for the time it was developed and something we take entirely for granted today," Robertson writes. "Multitasking, however, wasn't quite as we now think of it. Today's operating systems use mostly preemptive multitasking, where the operating system itself is in control of the execution and can stop any program at any time and hand off some computing power to another. The Apollo Guidance Computer relied on non-preemptive multitasking, whereby programs had to relinquish control back to the OS periodically. "

This is not to say that NASA relies on primitive technology. The Apollo computers were cutting-edge for their time, and NASA today pioneers the use of supercomputers for space science.

It is a marvel, though, that something as precise and daring as sending men to the moon, landing them, coordinating a rendezvous with their command module for the ride home and bringing the craft to rest in the ocean with enough precision for surface ships to reach the spot quickly could be done with less computing power than we can today hold in the palms of our hands.


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