Space exploration is insanely difficult at the best of times, and the five-year journey of the Juno spacecraft is pushing things even further. It is one of the most inspirational things we do, writes Alan Duffy.
Famously in space nobody can hear you scream, but if Juno's five-year journey to Jupiter had missed the orbital window then NASA JPL's collective scream would have tested that idea.
Watching live on NASA TV is a strange experience as we know that the signal from Juno takes 48 minutes to reach us, so "live" in this sense is sharing an experience of something that actually happened nearly an hour before.
The challenges facing Juno were immense. A 2.8 billion kilometre journey had only a 20km wide "window" to slow down and thread through. Too slow and you'd crash into the clouds or too fast and you'd bounce off into space. This is like hitting the bullseye of a dartboard with a dart thrown from one side of a city to the other.
Our mathematical models are so advanced that we were pretty confident of getting that nearly perfect. It is fortunate it's predictable because the entire Orbital Insertion is on autopilot because the time delay is so long our commands would be obsolete by the time we reached it. Having the entire craft spinning stabilises it much like a bullet spiralling keeps it on target.
The real issues are that the orbit aims to pass just 5000km above the surface of the cloud tops (akin to skimming just 8mm off the surface of a basketball) allowing an unrivalled close-up view of the planet but also ducking behind the deadly radiation belts around the equator.
Similar to Earth's Van Allen Belt this is a donut shaped region around Jupiter's equator but a million times greater. If Juno doesn't "duck" below this radiation it will potentially fry the electronics of the craft. Even so, after the planned 37 orbits Juno will have received the equivalent of 100 million dental X-rays - meaning the fragile electronics have to be protected within a titanium vault.
We've come a long way since Galileo turned a telescope to Jupiter and revealed that this point of light actually had, what we since have named, the Galilean Moons. We now know that Jupiter is a gas giant and the largest planet in the solar system and one of the major influences in forming the other planets and potentially life itself.
This is because its gravity has diverted asteroids and comets away from us (potentially getting hit itself!) but sometimes it throws these into our direction to the detriment of species on Earth at that point!
Juno will help us explore the origins of the gas giant, if it formed all at once from a collapsing gas cloud that gave birth to our sun or whether it instead grew around a rocky core 10 times bigger than Earth. We can learn about where it formed, and whether it has migrated in towards the sun and back out again as some models suggest (testable by measuring the water content of the planet).
One of the coolest things we will learn is what the structure of Jupiter is like, hidden beneath the cloud layers. This will be done directly be measuring it in a variety of wavelengths of light but also through measuring the magnetic field. We can even map the gravitational field itself using the motion of the spacecraft (which will be pulled up and down depending on the density and hence structure below). When you squeeze hydrogen gas to high pressures our theories suggest that it turns into "metallic hydrogen", a superconducting state that can generate the enormous magnetic field.
Juno will test that idea, but will peer even deeper to determine if Jupiter even has a solid core or if in fact you'd fall all the way through clouds and never hit land.
Juno is the latest in a sequence of outstanding missions from flying by Pluto, to landing on a comet and of course exploring the surface of Mars. It can take a decade to reach your target, but the building and planning of such a mission can be at least that long too.
This means that the golden age of space exploration is in fact a result of investment made in the 1990s if not earlier. Each mission represents sustained billion-dollar level funding commitments by NASA, ESA and universities and governments around the world. The payoffs are enormous, both in terms of what we learn but also direct economic benefits (NASA generates $US2.60 for the economy on every $1 invested) as well as enormous technological spinoffs.
Space exploration is insanely difficult, but nothing is quite so inspirational for students going into STEM and that very challenge is what drives current engineers and scientists to innovate and advance our technology, which is to the benefit of all of us on Earth.