The Secret Behind Radiation Hardened IT Equipment in Space
From 1961- 1975, during the worldwide space race and when the United States was making history with successful moon landings, technology at the time was booming. However, the Apollo 11 computer had a processor which ran at 0.043 MHz; meaning the iPhone in your pocket has over 100,000 times the processing power of the computer that landed man on the moon! More than 50 years later, its no secret that technology has developed into something we’d never dreamed possible. So, you’d think we’d at least be using updated systems in space today. Right?! Wrong. The computer hardware on board spacecraft computers is far from the newest and best around.
Until the recent Space X Flacon 9 rocket, space travel was conducted with outdated processors. Even the International Space Station (ISS) is operating with using two sets of three command and control multiplexer demultiplexer computers from 1988. Even the chips that made up the original Sony PlayStation in 1994 are faster! Well luckily for all future astronauts and space cowboys alike, the Space X Falcon 9 carrying a Dragon spacecraft sent to the ISS was the first commercial off-the-shelf (COTS) high-performance computer to orbit the earth. It just so happens to be among the first supercomputers in space.
What is Radiation Hardening and Why is Necessary?
Radiation hardened electronics can simply be defined as electronic components that have been designed and tested to provide some level of protection against penetrating radiation. If not protected, radiation can cause the computer components to malfunction, damage circuitry or cause the electronic device to completely shut down. Radiation hardening is essential when the electronics are used in environments where they will be exposed to high energy ionizing or space radiation.
There are three types of space radiation concerning electronic computer components used in space: galactic cosmic rays (GCRs), high energy solar radiation, and radiation belts. Galactic Cosmic Rays (GCRs) are electrons, protons or neutrons that originate outside of our solar system. High Energy Solar Radiation are emissions from the sun due to solar flares or explosions of stored magnetic energy. Radiation Belts contain trapped electrons and ions of varying energy levels. GCRs and solar radiation routinely reach the earth; therefore, they are present at all of the earth’s atmospheric levels.
For manned spaceships and satellite, continuous and reliable operation depends on being able to withstand space radiation. If you don’t already know the answer to the question, then you’re probably asking yourself why do we use spacecraft with such outdated processors? Well, by NASA's standards and the laws of physics, not just any computer can go into space. Computer components must be radiation hardened, especially the CPUs. Otherwise, they tend to fail due to the effects of ionizing radiation.
There is more modern hardware in space like the laptops used on the ISS. But those laptops are not high-performance computers. They're just ordinary laptops that are expected to fail. Actually, there are more than a hundred laptops on the ISS, and most are obsolete. In order to perform serious data mining, we want high-performance computing. Afterall these are the reasons we’re doing experiments on the space station.
The typical way to radiation-harden a computer
that will be used in space is to add redundancy to its circuits or use insulating substrates instead of the usual semiconductor wafers on chips. That’s not only very costly but laborious as well. Scientists believe that simply slowing down a system in adverse conditions can avoid glitches and keep the computer running.
The end goal is to develop a functional supercomputer for operation in space without spending years hardening it. By using off-the-shelf servers and custom-built software, scientists are trying to harden a computer using software by throttling its speed when there's a solar flare or other radiation hazard. If possible, astronauts will have the latest devices available, increasing their onboard capabilities.
The Effects of Space Radiation
There are a number of ways that computer components designers can radiation-harden their devices. One of the most common is to harden for total-ionizing-dose radiation - or the amount of radiation the device is expected to withstand for its entire life before problems occur. A typical requirement is for 100 kilorads of total-dose radiation hardness. The advancement of today's advanced electrical components is changing the total-dose picture. Specifically, the shrinking size of circuits on today's most modern chips is decreasing their exposure to total-dose radiation.
This trend is a double-edge sword because the steady shrinking of chip geometries also makes these devices even more vulnerable to other kinds of radiation effects, namely single-event upset (SEU) and single-event latchup (SEL). If not protected, radiation can cause the computer components to malfunction, damage circuitry or cause the electronic device to completely shut down.