Into The Eye of The Monster
In just two short days, the latest in a series of highly successful planetary missions, the Juno Mission to Jupiter, is scheduled to arrive at its destination for a July 4th polar-orbital insertion around the giant planet. Juno is the second spacecraft designed for NASA’s New Frontiers Program with the first being the brilliantly successful New Horizons that flew by Pluto on 14 July, 2015, ten days to the year sooner to the arrival of Juno. Unlike New Horizons however, and unlike any other spacecraft deployed beyond the orbit of Mars, Juno is powered exclusively by solar power. In the case of Juno, the craft is powered by 3 massive solar panel arrays consisting of 11 individual solar panels each, each measuring 2.9 meters wide and 8.9 meters long. Why such large arrays and why three of them? Jupiter is 5.2 Astronomical Units (AU) from the sun and thus receives less than 4% (1/25) the energy the Earth receives from the sun. In order to provide adequate power for all operations and to maintain a full battery charge, it was determined that the dimensions of the panels would have to be as such in order to comfortably meet the spacecraft’s 500 watt requirement.
Launch, Cruise and Arrival
Launched on 5 August, 2011, the craft was put on a trajectory for an October 2013 gravity assist with Earth, a maneuver that accelerates it an additional 3.9 km/sec to 140,000 Km/hr (39 km/sec). Following this gravity assist, the vehicle enters a 792-day “quiet cruise” phase, followed by a 178-day Jupiter Approach phase, a 4-day Jupiter Orbit Insertion Phase that began yesterday, 1 July, with the journey finally culminating in a 35-minute Jupiter Orbital Insertion burn. As Juno approaches Jupiter, the giant planet’s powerful gravity will accelerate the spacecraft to a blazing 160,000 Km/hr (44.4 Km/sec or 101,000 Mi/hr) to become the fastest object ever made, breaking the previous record set by New Horizons. Finally, having brilliantly passed every milestone on its 5 year sojourn, mission controllers transmitted the “ji4040” Autopilot command to the spacecraft at 3:15 pm, EDT, Thursday, 30 June for the July 4th JOI (Jupiter Orbital Insertion) burn, the most perilous phase of the mission. As I write this article, the vehicle has already entered its Final Approach Phase, culminating with the 35-minute JOI burn that begins at 8:18 pm, PDT, July 4th (11:18 pm, EDT, 3:18 UTC, July 5).
Mission Itinerary and Program
Unlike other missions such as the Galileo Mission to Jupiter where an equatorial orbit was established, Juno will be placed in a polar orbit providing for a first-time look at the Jovian poles and the opportunity for a “look down” view of active Jovian aurorae. The highly elliptical orbit will bring the spacecraft within 4,300 Km (2,688 mi) of the giant planet’s polar cloud decks. Once established in this orbit, the orbiter will begin its mission program using the suite of onboard instruments. In addition to providing a “bird’s eye view” of the Jovian polar regions, this orbit takes the spacecraft on a path that avoids any long-term exposure to Jupiter’s powerful radiation belts, regions that can damage or render inoperable the spacecraft’s primary electronics and solar panels. These electronics include communications and navigation modules and are thus placed in the “Juno Radiation Vault”, a 1 cm thick-walled cube of solid titanium.
The mission is scheduled to conclude in February 2018, after completing 37 14-day orbits of Jupiter. At that point, the probe will be deliberately de-orbited and burn up in Jupiter’s outer atmosphere, preventing any possibility of impact and biological contamination of Europa, the target of a subsequent major mission and one that will include a lander!
Public Access and Participation
A key aspect of NASA’s New Frontiers Program provides the opportunity for the public to play an expanded participatory and access role in a given mission when appropriate. The opportunity for expanded public participation in a major space mission is a great opportunity for teachers, educators and students alike. As soon as the spacecraft is in a stable orbit, JunoCAM will be activated providing the very first views of the Jovian poles. Like the brilliantly successful Cassini Mission to Saturn, public participation in and contribution to the mission is encouraged and is available through an online portal. Membership in the JunoCam community is available through the online portal where you can actively participate in the mission! If you’re an amateur astronomer (or a professional) you have the opportunity to upload and share your images of Jupiter and help mission scientists decide what points of interest JunoCam will photograph.
Where is Juno Now?
To view the position of Juno (as well as the position and status of any other mission) at any given moment, the Solar System Simulator and Explorer is available through NASA JPL and the California Institute of Technology. In a related story, the Space Telescope Science Institute just released new images obtained with the Hubble Space Telescope of Aurorae occurring in Jupiter’s North Polar region. Public access to the latest available data, images and content can be found on the Juno mission public website, NASA’s website for the mission and at Space Flight101.com/Juno.
As a fitting conclusion and to serve as a timeless reminder of what we can accomplish, to the heights we can climb, to what we can achieve, to the indefatigable human spirit, how we will one day make it to the stars [with difficulty-ad astra per aspera], the words of Isaac Newton, that “If I have seen further it is by standing on ye shoulders of Giants”, it should be noted that Juno carries a plaque dedicated to Galileo Galilei. It was provided by the Italian Space Agency and measures 7.1 by 5.1 centimeters and is made of flight-grade aluminum with a mass of 6 grams. It depicts a portrait of Galileo and a text in Galileo’s own hand, penned in January 1610, while observing what would later be known to be the Galilean moons.
All our science, measured against reality, is primitive and childlike-and yet it is the most precious thing we have
An index of all articles in this blog can be found here.