How to watch NASA's Juno spacecraft enter Jupiter's orbit

NASA launched its Jupiter-exploring Juno spacecraft on August 5, 2011, but thanks to some patriotic timing, it's arriving at the gas giant today on July 4th. That'll give space fans some additional fireworks, as NASA and JPL will be broadcasting the crucial orbit insertion starting at around 10:30 PM ET. If all goes well, the craft will fire its main engine for 35 minutes and scrub 1,212 mph from its current 37,000 mph velocity. That'll give it just the right speed to be captured into a 53-day orbit around the planet.

If you're a space nerd -- and even if you're not -- the event should be exciting. To catch it live, tune in to NASA's Juno Mission Control Live broadcast on Ustream, starting at 10:30 PM ET. Another way to follow along is with NASA's Eyes on Juno app for Mac or PC that gives you a simulated ride aboard the craft.

Juno has just one chance to make the crucial engine burn and achieve orbit -- if the motor fails, it'll go flying off into space. A miscalculation could also send it too close, as its first orbit will put it at a very tight 2,900 miles from the top of Jupiter's atmosphere. The Jovian planet has a very intense magnetic field, which could also knock out Juno's sensitive instruments, even though they're shielded by titanium. Did I mention that it takes 48 minutes for the craft to send a signal back to Earth?

Those potential issues will create a lot of suspense, but if things unfold as expected, Juno will be captured by Jupiter's gravity and enter orbit around 11:38 PM. From there, it'll point its antenna toward Earth, and start sending telemetry around 12:16 AM. Hopefully at that point, we'll get some nice images from the craft's high-resolution JunoCam (the first image is shown above).

It'll make two 53 day orbits, then do another engine burn to push it into a 14-day orbit, where the science will begin. Astronomers hope to discover whether Jupiter has a rocky core by measuring its magnetic field, for one. They also aim to discover more about metallic hydrogen, which nobody has been able to create on Earth. (On Jupiter, pressures amount to hundreds of millions of tons per square inch.)

There will also be lots of unprecedented high-resolution images of the planet, better showing its storms, bands and spots. Juno will do all this with just 500 watts of solar power, as Jupiter is five times farther from the source of its power, the Sun, than Earth.

Around November 3rd, NASA will take suggestions from the public as to where they should point Juno's cameras. On the 37th and final orbit, the space agency will deliberately steer Juno into Jupiter's clouds, where it'll burn up. NASA wants to ensure it doesn't crash into Jupiter's moon, Europa, and contaminate it with bacteria that may have sneaked onboard, however unlikely that scenario is.

The mission is programmed to last a relatively short 20 months, because the intense radiation is expected to quickly fry the spacecraft's electronics. If things go better than expected, however, the mission could be extended another few months. Bear in mind that they said the same thing about the Mars rover Opportunity, and the damn thing is still going.