NASA's Juno Probe Overcame Insane Obstacles to Reach Jupiter

What narrow misses did NASA's Juno probe face on the five-year journey to Jupiter, and it's acrobatic slip into the orbit of our solar system's largest planet?

NASA's Juno Probe Overcame Insane Obstacles to Reach Jupiter
After an almost five-year journey to the solar system’s largest planet, NASA's Juno spacecraft successfully entered Jupiter’s orbit during a 35-minute engine burn. Credits: Credits: NASA/JPL-Caltech

If you look at today's daily doodle on the homepage of Google, you'll see a cartoon of NASA’s Juno probe successfully entering the orbit of Jupiter. In the image, tiny video-game-like NASA scientists are jumping for joy in the mission control room, and it’s no stretch of the imagination to assume that here, art is certainly imitating life. In the minutes after Juno settled into the orbital path of our solar system’s largest planet, the project’s principle investigator Dr. Scott Bolton congratulated the mission team, saying, “We just did the hardest thing NASA’s ever done.”


Juno launched on August 5, 2011 and after a five-year journey, during which it traversed 1.7 billion miles, it has finally begun its 20-month orbit around Jupiter, collecting images and data, and searching for hints about the massive planet’s creation – hints that scientists hope will give way to clues about the origins of the entire universe.

So why, as Bolton indicated, was this mission potentially the hardest thing NASA has ever done? How many things had to go just right in order for Juno to slide into Jupiter’s orbit, punch-in its time card, and start the work it was designed to do? Bolton's joy at the mission's success can be measured in the gleeful ripping up of NASA's plan B media statement at the recent press conference.

In interviews leading up to yesterday’s success, Dr. Bolton described Jupiter as “a planet on steroids”. For the life of its mission, Juno will have to survive harsh radiation that will eventually destroy its electronic systems, despite being cased in a titanium vault. But things could have gone belly-up long ago, before Juno even got a chance to ride the orbital path.

To give an idea of the ambitiousness of Juno’s journey, Quartz perfectly described the mission as NASA throwing “a tiny object through 1.7 billion miles of space into an area that is only about tens of kilometers wide. It’s like throwing a basketball from London to New York and managing to hit the backboard perfectly to land the ball in the basket.”

To get to where it is now, Juno had to do a lot of things, but it also had to not do some very important things:

1. It had to not collide with a single asteroid in 1.7 billion miles, while passing through, um, an asteroid belt.

2. The mission was haunted by the ghosts of failures past. Thanks to NASA’s Mars Observer spacecraft, which disappeared in 1993, a residual fear that hung over the Juno mission was that the probe might lose communication and fall off the radar. Something seemingly trivial could have sealed a fate much like that of the Mars Observer, which spun out after a fuel leak and vanished.

3. There was also a plausible risk Juno could miss its window of opportunity when entering Jupiter’s orbit. Certainly not a dainty or light spacecraft, Juno was traveling at an incredible speed of 165,000 mph (nearly 100 times faster than a bullet) while being further accelerated by Jupiter’s massive gravity. The probe had to pump the brakes for 35 minutes straight, achieving a mere slowdown of 1,200 mph in that time – but it was just enough for Jupiter’s gravity to capture the probe in its orbit. Sailing past a target is a real and detrimental concern for space missions; in 2010, Japanese spacecraft Akatsuki’s was on-course to Venus when its engine failed to fire properly and it overshot the mark, sailing right past Venus. It had to wait six years to try again.

4. Adding another undesirable dose of danger, Jupiter has a thin but significant ring of debris in its orbit, which made crashing a major anxiety in the arrival stage of the mission. At Juno’s high speeds, even a small particle could have caused significant damage, or derailment. And had Juno not been able to slow down enough or had there been a navigation error that steered the probe too close to Jupiter’s mysterious cloudy atmosphere, the probe could have been torn to shreds.

5. For Juno’s arrival at Jupiter, the mission team switched off every system and instrument of the spacecraft that was not vital to the orbit entrance. In the past, NASA has suffered mission failures due to menial task confusion – a moment of incoordination while the craft tries to pat its head and rub its stomach at the same time – something that happened in July 2015, when the computer aboard the New Horizons crashed as it was passing Pluto, due to nothing more than interpreting simultaneous basic commands.

It’s easy to sit back from a position of relative safety now, doing that all-too-human thing of concurrently torturing and entertaining ourselves with the details of what could have gone wrong. At the end of the day, however, the words ‘rocket science’ are revered in popular culture for good reason. What made this mission one of the hardest things NASA has ever done was five years of nail-biting as Juno dodged danger after probable danger.

In NASA’s eyes, there was and is only one planned and acceptable way for Juno to end its mission: at the conclusion of 20 months, after its 37th orbit, the probe will dive selflessly into Jupiter and destruct. This dramatic measure is scheduled for February 20, 2018, and will ensure that Juno cannot crash into or spread any bacteria to Europa, one of Jupiter’s 67 known moons, speculated to be one of the more probable locations of life in our solar system.   

A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

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