The Juno probe has begun its scientific orbit around Jupiter: We speak to the man who helped build it about the challenges of reaching the red giant

Steve Hogarty
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Jupiter's northern pole as captured by the Juno spaceprobe (Source: NASA/JPL-Caltech/SwRI/MSSS)

As the Juno space probe approached Jupiter, the massive gravitational pull of our solar system’s largest planet accelerated the craft to a speed of 265,000km/h.

That made it the fastest man-made object in history. At its top speed, Juno could travel from Brighton to Aberdeen in under ten seconds.

Juno gathered speed by slingshotting around the inner solar system like an interplanetary billiard ball until, after a journey of more than five years, it reached its destination within half a second of its scheduled arrival time. Jim Crocker, vice president for space systems at Lockheed Martin and one of the chief engineers on the Juno project, laughs as he apologises for the delay. “Jupiter is very difficult to do,” he says. “We’ve only ever been there a couple of times.”

Crocker has spent most of his life working on space missions, from his involvement in the final Apollo trip in 1972, to the launches of the orbital research base SkyLab one year later and the Hubble Space Telescope in 1990. He talks about planets not with the effusive, pop-science grandiosity of a Mancunian BBC presenter, but with the demystifying pragmatism of a man discussing the differences between Pret sandwiches. These heavenly destinations are very real to him, and the challenges in getting there are just engineering problems to be solved.

“Five years in deep space exposes you to all kinds of thermal extremes and solar flare eruptions,” Crocker says, “so it was a trick just keeping Juno alive for that long in space.” On top of being battered by cosmic detritus on the half-decade outbound trip, Juno now contends with the inhospitality of Jupiter itself, a planet that’s home to the most intense magnetic and radioactive fields in our solar system. The probe’s most sensitive instruments are kept inside a shielded titanium vault, which protects them as the craft repeatedly plunges into the planet’s turbulent upper atmosphere.

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“Juno spends most of the time outside of Jupiter’s radiation fields,” says Crocker, illustrating the craft’s orbit in the industry-standard manner of using his fingertips to trace out its course in the air. “But then it comes screaming in along the cloud tops at just 3,000 miles above the planet. We quickly do all of our observations, we go back up, download all the data, decide what to do on the next pass and then swing back around and do it all again.”

This montage of 10 JunoCam images shows Jupiter growing and shrinking in apparent size before and after NASA's Juno spacecraft made its closest approach on 27 August, 2016. Credit: NASA/JPL-Caltech/SwRI/MSSS

This dive-bombing of Jupiter’s atmosphere – where wind speeds reach 360km/h, helium condenses into liquid metal rain and Earth-sized thunderstorms rage in clouds of corrosive ammonia crystals – take a toll on delicate Juno. Lockheed expects its craft to operate for only five years, a short life compared to some probes that have been happily orbiting Mars for decades.

And when its mission is complete, Juno can’t simply be left to rot in deep space like an abandoned Ford Fiesta; there are strict international rules on where the probe’s billion dollar robo-corpse must end up. The Outer Space Treaty prohibits the forward contamination of other worlds – NASA even employs a planetary protection officer, Catharine Conley, whose job it is to ensure these principles are upheld – and so probes are either scrubbed clean in highly sterilised environments before launch, or are doomed to meet a more fiery end in space.

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“NASA’s instructions are clear,” says Crocker. “Juno must eventually fall into and burn up in the Jovian atmosphere. That’s because some of the icy moons of Jupiter could potentially harbour alien bacteria – or some other form of life – within their oceans, and the last thing we want is for Juno to inadvertently crash into and contaminate one of these moons.”

When Crocker’s baby finally disintegrates above Jupiter’s skies, Lockheed Martin and NASA’s focus will have shifted to mankind’s most ambitious space mission yet. Lockheed is the prime contractor building Orion, NASA’s first spacecraft designed for manned, long-term deep-space exploration. This is the ship that will eventually ferry the first humans to Mars, forming the vanguard of a new generation of human-led space exploration. Orion is the project that will herald this generation’s Moon landing moment.

A close-up view of Jupiter's southern hemisphere, as seen by NASA's Juno spacecraft on 27 August. The JunoCam instrument captured this image with its red spectral filter when the spacecraft was about 23,600 miles (38,000 kilometers) above the cloud tops. Credit: NASA/JPL-Caltech/SwRI/MSSS

“Imagine if instead of Shackleton’s exploration of the Antarctic, we’d sent a robot to take those first pictures. It wouldn’t be the same. Exploration is something that humans want to do personally, we want to visit these places ourselves,” says Crocker as he looms like a giant over a scale model of the habitat module, aboard which the crew will spend most of their seven month journey.

Inside there’s a treadmill, ordinary looking save for the gravity-simulating bungee straps designed to tether the astronauts down as they exercise. Loss of muscle mass in zero-gravity is just one of the many physical challenges facing the first interplanetary explorers, the first of whom are unlikely to have the honour of stepping foot on the red planet. That job will continue to be the domain of rovers for some time, but by putting human controllers in orbit above Mars, the productivity of these robotic helpers will increase exponentially.

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Controlling a Martian robot from Earth is a sluggish task. It takes around 20 minutes for communications to reach Mars, so even the simplest of manoeuvres take days of meticulous planning. “The Russian rover Lunokhod that landed on the Moon travelled further in three months than the rovers on Mars have collectively ever travelled, simply because it’s much closer to us. So we want to land humans on one of the moons of Mars – Phobos and Deimos – and explore those while tele-operating down to rovers on the surface in near real-time. That’s really the first stage in sending humans to Mars.”

This infrared image gives an unprecedented view of the southern aurora of Jupiter, as captured by NASA's Juno spacecraft on August 27, 2016. Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

I nod along as if everything Crocker says is obviously correct, as if remote-controlling Martian robots from a comfortable seat up on Phobos is common sense and not some impossibly remote concept. The conversation moves on to talk of moon villages and Martian outposts, topics seemingly plucked from science-fiction and slotted into a reality that Crocker and Lockheed Martin are already building. Interest in space exploration hasn’t been this high since the 1960s, with private companies and world governments mobilising larger budgets with renewed enthusiasm and in spirited cooperation.

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“We’re seeing a lot of interest from young graduates now,” says Crocker. “They’re sending in resumes to come work for us because they’re excited to be part of the journey to Mars. They’re eager to be part of this journey of science and exploration, and they’re inspired by the discoveries that they’re seeing.

“And I think maybe The Martian didn’t hurt either.”

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