After nearly five years in space, Juno arrives at its destination: Jupiter.
By Mary O’KEEFE
When America’s Founding Fathers were planning their first celebration on the Fourth of July the celebration was to reach the skies, hence fireworks. But for this year’s Fourth of July those at the Jet Propulsion Laboratory took that reach past the skies and into the universe.
“Independence Day always is something to celebrate, but today we can add to America’s birthday another reason to cheer – Juno is at Jupiter,” said NASA Administrator Charlie Bolden in a statement on the Fourth of July. “And what is more American than a NASA mission going boldly where no spacecraft has gone before? With Juno, we will investigate the unknowns of Jupiter’s massive radiation belts to delve deep into not only the planet’s interior, but into how Jupiter was born and how our entire solar system evolved.”
After “cartwheeling” through space Juno has arrived at a safe orbit of the giant planet Jupiter.
“The primary objective [of Juno’s mission] has to do with the formation of the solar system. We want to understand how Jupiter formed,” said Scott Bolton, Juno principal investigator, Southwest Research Institute, San Antonio.
Prior to the July 4 orbiting Juno scientists and engineers invited media to the Jet Propulsion Laboratory to see a model of the spacecraft and to discuss the mission’s objectives.
Bolton shared a photo from the Hubble Space Telescope of how young stars form. The young stars form out of nebulae, which are gases that are mostly made of hydrogen and helium. These clouds collapse and a star is born. The leftovers from that collapse are what makes up the solar system.
“So in many ways what we are after is the recipe for a solar system. How do you make planets? And like any recipe one of the first things we want to figure out is the ingredient list,” Bolton said.
Finding out how Jupiter was formed will give the scientists answers as to how other planets were formed.
“Jupiter is the largest [planet and] the most likely [planet] that was formed first,” he said.
Getting to Jupiter was not easy. Juno launched on Aug. 5, 2011 and is a huge spacecraft with large solar wings. According to the JPL Juno website, “Jupiter’s orbit is five times farther from the Sun than Earth so the giant planet receives 25 times less sunlight than Earth. Juno will be the first solar-powered spacecraft designed by NASA to operate at such a great distance from the sun, thus the surface area of solar panels required to generate adequate power is quite large. Three solar panels extend outward from Juno’s hexagonal body, giving the overall spacecraft a span of about 66 feet (20 meters). The solar panels will remain in sunlight continuously from launch through end of mission, except for a few minutes during the Earth flyby. Before launch, the solar panels folded into four-hinged segments so that the spacecraft can fit into the launch vehicle.”
Juno will be the first spacecraft to orbit the polar region of Jupiter, an area scientists are very interested in.
It is also the first spacecraft that has data collecting equipment safely tucked away in a special radiation shielded vault, thus keeping it protected from the planet’s extreme radiation. The equipment will be able to send a variety of data back to mission control.
“What Juno is able to do is see through [Jupiter’s] cloud layers for the first time and investigate how deep these features go. Are they on the surface or do they penetrate down?” Bolton asked.
And Jupiter is a massive planet – 1000 Earths can fit inside Jupiter. It has more mass than everything else in the solar system put together, he added.
“So if I add up all the planets, all the comets and all the asteroids they still don’t add up to Jupiter,” Bolton said.
But it is what Jupiter is made of that is of the most interest to scientists, who refer to Jupiter as having an enrichment of heavy elements. It has hydrogen and helium like the sun but also heavy elements like carbon, nitrogen and sulfur.
Over the next few months, Juno’s mission and science teams will perform final testing on the spacecraft’s subsystems, final calibration of science instruments and some science collection.
“Our official science collection phase begins in October, but we’ve figured out a way to collect data a lot earlier than that,” said Bolton. “Which when you’re talking about the single biggest planetary body in the solar system is a really good thing. There is a lot to see and do here.”