The Orion spacecraft is no smarter than your phone
Orion, whose launch this morning was delayed until at least Friday, doesn't carry state-of-the-art computers and its processors are 12 years old -- making them ancient in tech years. The spacecraft, according to one NASA engineer, is built to be rugged and reliable in the face of G forces, massive amounts of radiation and the other rigors of space.
When a spacecraft is designed to carry humans into deep space, reliability is more important than using the latest and most powerful computers, said Matt Lemke, NASA's deputy manager for Orion's avionics, power and software team.
"Compared to the [Intel] Core i5 in your laptop, it's much slower -- much less powerful," Lemke told Computerworld. "It's probably not any faster than your smartphone. But it's not about the speed as much as the ruggedness and the reliability. I just need to make sure it will always work."
The space agency is accustomed to using older technology.
NASA's latest and most powerful rover to arrive and work on Mars, Curiosity, also runs on a computer no more powerful than the one in a smartphone.
Now, it's relying on similar power in a spacecraft that will not just drive across the surface of another planet but will ferry human cargo through space.
Orion is the first deep space vehicle that NASA has built since the Apollo missions of the 1960s and 1970s. However, unlike the more recent space shuttle, Orion is built to go far beyond Earth orbit.
NASA expects Orion to travel to an asteroid in the 2020s and then to carry astronauts to and from Mars in the 2030s.
The spacecraft was set to make its initial test flight Thursday morning. But after a series of issues including wind gusts and a glitchy rocket valve, it was unable to lift off from its launch pad at Cape Canaveral Air Force Station. The space agency plans to try again during a launch window that's open from 7:05 a.m. to 9:44 a.m. ET on Friday.
Since this spacecraft was constructed about 50 years after Apollo, it's obviously far more advanced, carrying state-of-the-art parachutes, heat shield and life-support systems.
As for Orion's main computer, the space agency is using a Honeywell International Inc. flight computer originally built for Boeing's 787 jet airliner. The computer, which at this point runs everything on the uncrewed spacecraft, has been ruggedized for space travel with larger housing, a thicker circuit board and hardware to minimize vibrations.
"The one thing we really like about this computer is that it doesn't get destroyed by radiation," said Lemke. "It can be upset, but it won't fail. We've done a lot of testing on the different parts in the computer. When it sees radiation, it might have to reset but it will come back up and work again."
It takes just 20 seconds for the computer to reset, but for a system that runs everything on a craft hurtling through space at thousands of miles an hour, even 20 seconds of down time is too much. That's why there are two flight computers onboard, giving the spacecraft a redundant system.
For Orion's first test flight, which will have the spacecraft flying through an area of high radiation known as the Van Allan belt, the vehicle will carry a third computer as an extra precaution.
"Since we'll be going through a lot of radiation for quite a while, we've added another computer -- a third -- so if the two main computers go down because of radiation, this one will know the state of the vehicle if those two are lost," said Lemke. "When the first two reset, they'll go to the third and get the current data."
When it comes to computer redundancy, it's all about probabilities.
There's a chance of a single onboard computer going down in one out of every 3.7 missions, according to Lemke. And there's a one-in-8,500 chance of the second computer going down within 20 seconds of the first.
"There is a lot of uncertainty in just how bad the radiation is in the Van Allen belt, so we knew the probability could really be worse than what was calculated," said Lemke. "We don't want to even take a one-in-8,500 risk, so that's where the third computer came in."
The chance of losing all three computers at the same time is one in 1,870,000 missions.
"What does all of this mean" asked Lemke. "It means that we won't be at all surprised if we experience a flight computer reset during the mission but we are very confident that radiation won't cause a problem with this test flight."
The computers are running IBM's PowerPC 750FX single-core processors, which were first launched in 2002.
NASA fit two of the processors into each flight computer, setting them up to run identical software and monitor each other. If the processors don't do the exact same thing, the system will stop giving commands and reset itself.
"The processors are obsolete already but they have the property of just getting upset by radiation, instead of being permanently damaged," said Lemke, noting that NASA has been using the processors for more than 10 years. "You could do it with something newer, but all the engineering that would go into making it work right would make it a lot more expensive for us to build it."
A lot of the technology on Orion came from either the airline industry or the U.S. military. For instance, the spacecraft's beacons and some of its antennas are based on technology that was first developed for the military.
Orion is trying out a new technology, too.
Lemke explained that while basic data transfers, like images being sent from a camera to onboard storage, will be handled by regular gigabit Ethernet, Orion will be the first spacecraft to be outfitted with Time-Triggered Ethernet or TTEthernet for critical data transfers.
With basic Ethernet, data packets are delivered with no guarantee that they'll arrive at a certain time. But when onboard data communications are needed to fire Orion's engines at an exact moment or to navigate the spacecraft, data needs to be delivered very precisely.
"The Time-Triggered Ethernet gives you a time-based guaranteed delivery," said Lemke. "It lets us use Ethernet for controlling the entire spacecraft -- every command the computer sends, all the data from the sensors that goes to the flight computers."
Orion has one basic Ethernet cable for basic communications, but all critical data will travel across three different Ethernet lines.
"Orion is not incredibly high tech, but compared to what else is flying in space, it's leading edge," said Lemke. "It's much more capable than the space station or more capable than what the shuttles were. It's state-of-the-art compared to that ,but it's not state-of-the-art compared to what you can get at Best Buy.
"But what you get at Best Buy doesn't need to withstand the extreme vibrations of launch, the vacuum of space with wide temperature swings and then come back to Earth with lots of pyrotechnics and thousands and thousands of Gs of shock and then land in the water and potentially be submerged -- and still operate."