NASA's Juno is about to reach Jupiter after a 5-year journey. I visited JPL before the big show.

Today is a big day for NASA. At 8:18pm Pacific, the Juno spacecraft headed for Jupiter will fire off its main thrusters and, if all goes well, begin orbiting the gas giant. It's a make-it-or-break-it moment and thousands of eyes will be watching the live event.

There's a lot at stake here. Jupiter has the strongest magnetic fields and gravity, as well as the highest radiation levels, of any planet in our solar system. In fact, Jupiter behaves more like a mini sun.

You know those dogs that are raised with a bunch of cats and then they do silly cat-like things like sit in bags? Jupiter is like that, a planet that thinks it's a sun. It's an intense, swirling ball of metallic hydrogen and helium.

NASA's Jet Propulsion Laboratory gave me and a couple dozen of my internet/social media peers a grand tour of JPL's facilities, where the Juno mission all came together.

At the social media meet-up, we were given opportunities to ask questions of Juno scientists at JPL, all of whom seemed surprisingly calm and collected, given that they've been waiting years for this critical moment. We also learned about some of the unique technology on Juno and other missions, and about the extensive public outreach that NASA provides. If a spacecraft flies by something amazing in space and nobody tweets or Facebooks it, does it make a sound? Not an issue with this mission. It's a first for the entire human race.

About the video: At a press briefing earlier today, project manager Rick Nybakken demonstrated with models exactly what Juno is going to do this evening. At 7:30pm Pacific Time, NASA commentary will begin. Juno is expected to pass by Jupiter starting around this time, and by 8:18pm, the main engine burn is scheduled to start. 35 minutes or so after that, around 8:53pm PT, the burn will finish, and that should be just the right amount for Juno to make the orbit we want.

Note that these times in the schedule JPL released are when we hear the events back here on Earth (8:18 for the burn start, for instance). In fact, the events really happen 48 minutes earlier, way out there in space. It takes that long for the data to travel back here.

The first two orbits will be 53 and a half days long. What happens if the engine burn doesn't quite work? It needs to occur for a minimum of 20 minutes to get into some sort of orbit, though it would really suck if that orbit were a thousand days long. If for some reason it burns for too short of a time, or not at all, Juno will continue on its current trajectory and we will watch our tax dollars being flung into the far reaches of space like a bullet. But these NASA people give me confidence that that won't happen.

Photo: Katherine Leipper

Walking through Mission Control, aka "the Darkroom," was amazing. Yes, it really does look like a sci-fi movie set. This control room has been in use for 52 years.

I asked why it was so dark in there and Jim McClure, a manager, told an interesting story: One day in the '60s, they turned the lights off because it was getting really hot. That lasted for a little while, until they got in trouble when an inspector came through and told them the lights had to be turned back on. Upon doing so, they noticed that the ceiling was covered in cigarette smoke stains, so they just painted the whole room black. Later the interior was redesigned to the way it is now, dark but lit in all the right places.

Photo: Katherine Leipper

NASA's homegrown AVIS software runs on a Solaris-based OS. Once data starts being logged by Juno, it will take 48 minutes to reach this control room.

Photo: Katherine Leipper

Calm before the storm. Above, the control room right next to the Darkroom where it's all going down later today.

Photo: Katherine Leipper

Above: Checking out one of the oldest and largest cleanrooms, this time behind glass, from the second floor. A mannequin in full protective gear stands in front of a full-sized model of one of the Juno solar arrays.

This is a Class 10,000 cleanroom, which means that there are that many pieces of 0.5-micron dust or less per cubic foot in the room. Elsewhere, NASA has a Class 10 cleanroom, the dress code for which is a little more extreme.

Photo: Katherine Leipper

This looks like a trampoline and I definitely fantasized about jumping on it but it's actually a clean bag containing a spare heat shield that's headed to the Mars Curiosity Rover in 2020.

As part of the public engagement aspect, NASA has a really slick desktop app that lets you travel around the solar system with Juno. Kevin Hussey of the JPL Visualization team gave us a demo of Nasa's Eyes. All the 3D graphics are rendered with OpenGL, but give them another year or so – they're working on converting it to WebGL so you'll be able to view everything in your browser, and it will be open source(!!!)

Photo: Katherine Leipper

A model of itty bitty Sojourner (in the shadow of Curiosity's wheel), another patriotic explorer that landed on Mars on July 4th, 1997.

Photo: Katherine Leipper

Juno claims a lot of firsts. Besides being the first spacecraft with a radiation vault, it's also the first to utilize 3D printed parts. Remember, Juno was launched in 2011, before most people had even heard of the technology, and these brackets were designed years before that. They are for holding waveguide tubes, fabricated with a process called laser sintering that allows metal powder to be melted with an electron beam. The one on the left is the rough piece spit out by the printer, and the one on the right is what it looks like after the surface has been machined.

Photo: Katherine Leipper

Carbon nanotubes, another relatively new technology, are also being utilized. Parts of the spacecraft are wrapped in these to ensure the entire thing stays grounded, protecting it from being charged by particles, which could mess up the equipment and readings.

(Previously: “The closest I'll get to Jupiter is this JPL clean room”)

Image, NASA: The first image of Jupiter taken by Junocam.

A model of the Juno spacecraft is seen at a news briefing, held before Juno enters orbit around Jupiter, on Thursday, June 30, 2016 at the Jet Propulsion Laboratory (JPL) in Pasadena, CA. The Juno mission launched August 5, 2011 and will arrive at Jupiter July 4, 2016 to orbit the planet for 20 months and collect data on the planetary core, map the magnetic field, and measure the amount of water and ammonia in the atmosphere. Photo Credit: (NASA/Aubrey Gemignani)