More than five years of work by a team of local Lockheed Martin engineers came to a thrilling conclusion July 4 when NASA’s Juno spacecraft was flawlessly placed into orbit around Jupiter.
“Tonight, 540 million miles away, Juno performed a precisely choreographed dance at blazing speeds with the largest, most intense planet in our solar system,” Guy Beutelschies, director of interplanetary missions at Lockheed Martin Space Systems, said in a company news release. “Since launch, Juno has operated exceptionally well, and the flawless orbit insertion is a testament to everyone working on Juno and their focus on getting this amazing spacecraft to its destination. NASA now has a science laboratory orbiting Jupiter.”
Launched Aug. 5, 2011, from Cape Canaveral, Fla., by Colorado-based United Launch Alliance, Juno was engineered and manufactured at Lockheed Martin’s Space Systems facility in South Jeffco. A 30-member flight team also based locally has been operating the spacecraft for its almost five-year, 1.76-billion-mile journey to Jupiter, said Lockheed Martin spokesman Gary Napier.
Juno had to travel more than three times the distance to its destination because of the varying and constant orbits of Earth and Jupiter around the sun, Napier said. In other words, there was no direct path from Earth to Jupiter for Juno to follow. Scientists had to predict where Jupiter would be in its orbit when Juno neared the solar system’s largest planet.
“Think of it as though you were playing hockey with Wayne Gretzky,” Napier said. “Because players are always moving, you have to guess where Gretzky is going to be (on the ice) and pass the puck to him there.
“Jupiter is always moving, so we were kind of chasing it. Juno had to take a long, circular route, which is why it took five years.”
For the flight team, the process for navigating Juno through space sounds a lot easier than the actual work scientists and engineers have been conducting for the last several years. There is no group of pilots flying the spacecraft with a joystick and a highly sophisticated system of cameras beaming images to Earth from space. Instead, Lockheed Martin’s flight team takes sequences developed by Southwest Research Institute in San Antonio and sends them by radio signal to an autonomous robot aboard Juno, which then performs the system of commands, Napier said.
However, it takes 48 minutes for those sequences to travel the 540 million miles to Jupiter, which means scientists must send the commands long before a flight maneuver needs to be executed. Case in point: Lockheed’s flight team sent the commands for Juno to slow down and enter Jupiter’s orbit days in advance, Napier said during an interview with the Courier on July 5.
The sequence was sent so early because the robot needed to execute the flight plan perfectly for the mission to be a success, Napier said. Like cell phones, the robot was built with an internal clock, which means it has the ability to perform duties when cued, not necessarily at the moment it receives a radio signal from South Jeffco.
“It’s like setting the alarm on your cell phone,” Napier said. “Even if you turn off your phone, there is an internal clock that sets the alarm off when you program it to.”
But unlike here on Earth, where an alarm failing to go off might mean being late to work and a conversation with the boss, anything less than pinpoint accuracy on behalf of the flight team could mean jeopardizing the entire mission, Napier said. Scientists used those extra days to test and retest their calculations for Juno’s optimal flight path en route to its orbit around Jupiter.
As Juno neared Jupiter, it was traveling 130,000 mph relative to the planet, or the equivalent of 165,000 mph here on Earth, Napier said. In order to guide Juno into Jupiter’s orbit, the flight team needed to slow the craft by just 1,212 mph. To accomplish that goal, scientists had to burn off the remaining fuel in Juno’s main engine, a process that would take an estimated 35 minutes.
The robot executed the sequence to burn off the engine at 9:18 p.m. July 4, allowing Juno to be captured by Jupiter’s massive gravity and placed into a large, elliptical orbit high above the planet’s north pole. Lockheed Martin’s flight team missed its 35-minute estimate by a fraction of a second.
“The spacecraft responded to perfection, and the engine shut off within a second of our prediction,” Napier said. “It was flawless; just perfect.”
Jupiter is the solar system’s largest planet. It is more than two-and-a-half times as massive as all the other planets combined, according to a Lockheed Martin news release.
The mission’s primary goal is to improve understanding of the formation and evolution of Jupiter, which could also provide insight into the creation of the solar system as a whole, Napier said. Over the next 20 months, mission scientists will investigate the planet's origins, interior structure, deep atmosphere and magnetosphere.
Jupiter also is one of the most radioactive planets in the solar system, Napier said. During Juno’s mission, which will encompass 33 elliptical orbits during the next year, the spacecraft will be exposed to the equivalent of 100 million dental X-rays.
To protect the sensitive spacecraft electronics, Lockheed Martin engineers constructed a unique titanium vault mounted between Juno’s main structure and high-gain antenna, the release stated. The vault acts as shielding to protect the critical spacecraft computers and instrument computers from the high-energy particles it will encounter when the orbit comes close to the planet, the news release stated.
NASA’s Jet Propulsion Laboratory manages the Juno mission for the principal investigator, Dr. Scott Bolton of Southwest Research Institute in San Antonio. Juno is part of NASA's New Frontiers Program, which is managed at NASA's Marshall Space Flight Center in Huntsville, Ala., for NASA's Science Mission Directorate. The California Institute of Technology in Pasadena manages the Jet Propulsion Laboratory for NASA.