Solar Spacecraft At Jupiter’s Doorstep For Historic Close-up Visit From Earth After 5-year Journey

Solar spacecraft Juno arrived at the outer reaches of Jupiter on Monday, July 4, for an exploratory plunge into its orbit, farther than any other rocket ship before. The National Aeronautics and Space Administration (NASA) has been watching the Juno probe throughout its epic, 5-year journey to the largest planet in the Solar System for the purpose of collecting data.

According to CNN, the spinning robotic probe as wide as a basketball court and running on solar batteries, has followed a trajectory to a point where it can make its dive into the unknown. Looking somewhat like a flying windmill, the spacecraft will descend into orbit and then the exploration of Jupiter begins. Juno will circle Jupiter 37 times over 20 months, just about 2,600 miles above the planet’s dense clouds.

Because nothing much is known about the huge gaseous planet despite its being so big it can be seen from Earth without a telescope, science instruments on board the solar spacecraft will examine auroras at Jupiter’s perimeter. Scientists hope the probe’s findings will help them understand the planet’s origins, structure, atmosphere, and magnetosphere.

The solar-driven spacecraft is regarded as key to unraveling the mystery of what lies beneath the swirling storm clouds. Scientists are not even sure what’s at the level below the turbulent atmosphere, if there is a solid core or not. There’s also the question of what drives the invisible magnetosphere, Jupiter’s enormous magnetic field. If bathed in light, it would appear twice the size of the full Moon from Earth.

Juno standing by
Scott Bolton, the principal investigator for Juno with the Southwest Research Institute in San Antonio, Texas, is watching the solar spacecraft’s progress, along with the rest of the Juno team manning computer monitors. The probe is supposed to fire its main engine for 35 minutes starting at 11:18 p.m. ET on Monday. The maneuver would slow the spacecraft by about 1,212 miles per hour, allowing it to be drawn into orbit around Jupiter.

Before the solar spacecraft can emit tones indicating a successful completion of the engine firing, the estimated time will be 12:30 a.m. ET on Tuesday. The downside to this scenario is some glitch causing Juno’s batteries to die before it can face the sun at the other side of Jupiter. A swing back around the planet would position the probe’s huge solar arrays in sunlight to recharge. Bolton shared his anxiety about this maneuver with reporters.

“I’m really just nervous that the whole orbit insertion rocket burn is going to work enough to get us into orbit and then allow us to turn back to the sun before we run out of battery power. You’re on battery power. The whole game is get back to the sun before you run out of battery.”

Juno launched
Prior to Juno, the exploration of Jupiter has been conducted by automated spacecraft doing observations. Starting with Pioneer 10 traversing the Jovian system in 1973, NASA has launched seven further spacecraft missions, all but one flybys observing without landing or entering orbit. The 1995 Galileo spacecraft is the only one to have entered Jupiter’s orbit and conducted studies until 2003. The Juno solar spacecraft will fly at a record-breaking height of 2,600 miles above the cloud tops, 3,000 miles closer to Jupiter’s surface than any other mission has ever achieved.

According to BBC, if the solar spacecraft‘s engine fails to fire at the right time, or for an insufficient period, the $1.1 billion venture will simply fly straight past Jupiter and into the oblivion of deep space. The mission team will be steering blind while Juno’s main dish is averted from Earth during the braking procedure, so events will be tracked via a series of simple tones sent back through the probe’s low-gain antenna.

Science Alert reports that Juno will slam on the brakes by firing its engines after reaching a maximum speed of 165,000 miles per hour, fast enough to fly around Earth in 9 minutes. The trick then is for the solar spacecraft weighing 3,500 pounds and barreling through space at 215 times the speed of sound, to slow down. The engines will fire for 35 minutes straight, burning through 17,600 pounds of fuel in the process, enabling Juno to decelerate enough to merge into Jupiter’s orbit.

There, the solar spacecraft will remain over the next 18 months, providing an unprecedented look at Jupiter’s powerful gravitational and magnetic fields.

Juno has only one shot at this, and if it misses Jupiter, it will be in deep space with no chance of return.

[Image via Shutterstock]