There’s a lot that can go wrong on any mission to the Moon.
There’s the intense blast at takeoff, the various stresses of the 239,000-mile voyage through space and then the adjustment to the extreme temperatures and other extraterrestrial conditions on the Moon itself.
So, assembling a cellular LTE/4G network that can survive that journey and then be successfully deployed on the lunar surface is no simple task. It requires considering how all the shock, vibration and acceleration at takeoff, and the various other issues along the way, could affect the sensitive cellular and electrical equipment as it shuttles toward a destination where no repair crews exist.
That’s the job of Holly Rubin. For the past five years, she has been thinking about anything that could go awry and testing the equipment for every eventuality ahead of next year’s planned mission.
“It’s not going to be an easy ride,” said Rubin, the reliability lead of the Nokia Bell Labs’ flagship project to the Moon. “We are trying to make something work under conditions that are not typical of terrestrial networks.”
Nokia is working with NASA to deploy the first-ever 4G/LTE network on the Moon to demonstrate how advanced cellular technologies can be used for critical communications in future planetary exploration. The uncrewed, robotic mission, dubbed IM-2, looks to pave the way to a sustainable human presence on the lunar surface.
In more than 35 years as a reliability scientist, Rubin has plenty of experience in testing the various aspects of cellular networks on Earth. A Distinguished Member of Technical Staff at Nokia, she is well-positioned as a “devil’s advocate” who bends systems till their point of breaking, searching for weaknesses that need to be fixed before they are deployed so that everything will function properly in real time.
But preparing a network for the Moon has introduced a whole new set of challenges. Rubin says she wouldn’t have it any other way.
“I’m excited and I’m nervous. Space is hard, it really is,” she said. “But this is also the highlight of my career. It’s a huge technical challenge and then there is the ‘cool’ factor. It’s just so different.”
A shocking journey
The first, and most obvious, challenge of the mission is getting there, and the most perilous part will be the initial blast off.
A rocket launch is essentially a controlled, sustained explosion that accelerates the rocket at enormous speeds, and it generates two big threats to the integrity of any equipment: vibration and shock.
Vibration is caused by the rocket’s engines and the enormous friction created when punching through the Earth’s atmosphere. The vibration at launch could be potentially catastrophic, causing the network equipment to literally shake itself apart.
Then there is shock and the effects of extreme G-forces from the initial launch and the larger shock generated by the separation of the rockets that could affect the network equipment. Finally, when the nose cone that protects the payload during liftoff is ejected, the equipment will experience another big jolt.
“You want to test to conditions beyond your expectations to make sure that you have built in margins and to strengthen anything that may be a weak point,” Rubin explained.
She has conducted endless tests. She’s shaken the base station on vibration tables. She’s placed it in giant centrifuges that simulate the intense acceleration forces experienced during launch.
And just in case, Nokia also designed the system to be fully redundant. So, if for some reason the base station doesn’t work, we can switch to another.
Rubin said she will only start to relax when the equipment is turned on successfully on the Moon. But many obstacles will remain.
The mission will need to cope with lunar dust, cosmic radiation, temperatures down to -100⁰C and the vacuum of space. Rubin’s team has done all it can to replace or reduce risk from any components known to be unable to survive these conditions.
But there is only so much she can control. For example, there are galactic cosmic rays that come from outer space and could cause damage to the electronics.
Then the hardware will have to hold up under the stresses of the Moon. All the preparations regarding weight constraints and thermal management will need to go smoothly so that the compact LTE/4G network can be mounted on Intuitive Machines’ Nova-C lander, enabling wireless communications with Lunar Outpost’s MAPP rover as it traverses the lunar surface.
“The level of testing we had to do was totally different, like how hard we had to shake things. A priori, we didn’t know how the hardware was going to respond to the required levels of shock and vibration. Many of us thought there would be a lot of failures,” she said. “But in general, it behaved really well.”
The extreme testing was designed for the LTE/4G network to survive its two-week mission during lunar daylight. It’s aim is to send back a live video feed, telemetry and network measurements collected across the rover’s multi-kilometer path near the Shackleton crater at the lunar south pole.
Among its other goals, the IM-2 lunar mission will also be searching for ice in hopes that it can produce water that astronauts could convert to breathable oxygen and even use to create fuel for an eventual journey to Mars.
Following countless calculations, lab simulations and tests, Nokia recently conducted a comprehensive field test in Colorado that tried to create the closest comparisons to conditions on the Moon.
“So, my job is now mostly done,” Rubin said. “From my perspective, we have qualified the hardware, it’s been shipped, and it is ready to be integrated.”
Space: The final frontier
Rubin’s journey to space began in the backyard of her childhood home, looking at the stars through a telescope with her dad. The interest was compounded by reading Isaac Asimov science fiction books and watching Star Trek on TV.
Her early studies revolved around mathematics. But a desire to delve into a field with more practical applications led her to chemistry and she went on to earn a BA in chemistry from Rutgers and a PhD in chemistry from Princeton.
Starting out at Bell Labs when it was still part of AT&T, she has stayed with the same company as it has passed though Alcatel Lucent and eventually Nokia.
Her varied work experience includes mitigating the reliability impact of aggressive environments on electronic equipment, assembly material qualification, component and optoelectronic module qualification, manufacturing process development, warranty expense reduction initiatives, introduction of a corporate component part numbering scheme and technology road mapping.
She said it was all interesting, but nothing compared to her current project. Going forward, she hopes to keep working on space-related technology and keep being a part of the triumphant Bell Labs return to space.
It’s been more than 60 years since we launched Telstar 1, the first communications satellite capable of relaying TV signals between Europe and North America. Two years later, in 1964, a pair of Bell Labs researchers, Arno Penzias and Robert Wilson, discovered cosmic microwave background radiation, one of the strongest pieces of evidence supporting the “Big Bang” theory of the explosive origin of the universe.
Bell Labs was also responsible for system analysis and evaluation for “Project Mercury,” the first U.S. program to put a man in space. It also offered technical advice to the Gemini and Apollo programs, which eventually landed the first man on the Moon.
Rubin said it was a thrill to share this chapter of her career with her husband, children and friends. She was only sorry that her father was no longer around to enjoy it too.
“This would have been so exciting for him,” she said.