Originally posted to 13.7 Cosmos & Culture on 7/6/2016
Right when Steve Spielberg's rendition of Roald Dahl's classic The BFG hit the screens here on Earth without the expected impact, NASA's probe Juno, in a spectacular performance, entered orbit around monstrous, stormy Jupiter — our solar system's "unfriendly" giant.
NASA engineers have all the right to brag. What they did was tremendous, sending a probe to one of the most inhospitable places in the solar system.
Picture Juno getting to Jupiter right on July 4, after a five-year journey, its engines powered by solar energy (not nuclear!). Jupiter's four huge moons (among more than 60 others) each rotate at different speeds, pulling on Juno. All that gravitational tugging was computed faultlessly to allow the spacecraft to enter a stable orbit for 20 months, for a total of 37 circumnavigations at only about 3,100 miles above Jupiter's cloud tops. The probe will be in a polar orbit where it will study the planet's enormous magnetic fields, and its core and chemical composition. You can "hear" the effect on the probe as it passed into Jupiter's magnetic field in one of the videos produced from Juno's data by scientists at the Jet Propulsion Lab. Hard to not get absolutely amazed and somewhat spooked by this, the distant reality of another world, so different from ours.
Given the planet's gaseous composition, scientists hope to be able to "see" features in the magnetic field that here remain buried under Earth's thick rocky crust. In particular, the goal is to understand the "dynamo" mechanism that generates Jupiter's magnetic field, that must share many properties with our own. But there are many unknowns, and the sheer violence of the local conditions can be deadly to the mission. Juno is the most heavily shielded spacecraft ever launched, so that it can — hopefully — sustain the bombardment of radiation and particles that it's sure to encounter.
In 1610, Galileo shattered the prevalent cosmic view with his telescope. One of his most remarkable discoveries was that Jupiter had moons (he could see only the four largest), something that flew on the face of the then dominant Aristotelian worldview, where the Earth was the center of the cosmos and everything revolved around it. If Jupiter, a planet, could have moons, Earth wasn't that special.
Historians write about the strong emotions Galileo must have felt when he realized he was the first human to see something new about the universe. The result, after his work was combined with that of Johannes Kepler in Isaac Newton's universal law of gravitation, was a completely new way to look at the cosmos and, as a consequence, at ourselves. Only 400 years later, we are actually sending probes directly to that distant world, to get a closer look.
Some of the scientists in Juno's mission will be the first ones to see things about Jupiter no one has ever seen before. In the brief moments before they make their discoveries public, as the new torch bearers of our enduring search for knowledge, they will share a silent bond with the Italian pioneer. And yet it moves!