Juno: NASA's Second New Frontiers Mission

Juno Mission Insignia

Juno Mission Insignia – Credit: NASA

NASA’s New Frontiers program is a set of solar system exploration missions designed to address “strategic goals in planetary science through a series of moderate size space missions” (you can read the entire program plan here). New Frontiers consolidates a number of long-term space missions into a single program that share a funding source, management structure, and goals, yet maintain their independent identities. New Horizons, NASA’s recent mission to Pluto and the Kuiper Belt, is considered the first mission of the New Frontiers program. The second mission is named Juno. Launched in 2011 with its sights set on our solar system’s red-spotted giant, Juno is poised to arrive at Jupiter on July 4, 2016. Let’s take a look at the mission and what we can expect to learn.

Juno: What’s In a Name?

Juno takes its name from Greek and Roman mythology. NASA draws the connection between the spacecraft and the myths as such:

Jupiter drew a veil of clouds around himself to hide his mischief. It was Jupiter’s wife, the goddess Juno, who was able to peer through the clouds and reveal Jupiter’s true nature. The Juno spacecraft will also look beneath the clouds to see what the planet is up to, not seeking signs of misbehavior, but helping us to understand the planet’s structure and history.

 

(It’s probably for the best that they left out the part about how Juno was, in addition to being Jupiter’s wife, also his sister.)

Juno Lifts Off

Juno Lifts Off – Credit: NASA/Bill Ingalls

Launch and Earth Fly-by

Juno launched atop the reliable and powerful Atlas V rocket engine on August 5, 2011. This engine contained five solid rocket boosters, along with a Centaur upper stage engine. The launch was flawless. After the solid rocket boosters were expended and jettisoned, the Centaur upper stage ignited and burned for six minutes, placing Juno in a parking orbit around the Earth. Juno coasted for thirty minutes towards the destination for the second Centaur burn. 40 minutes after lift-off from Cape Canaveral, the second Centaur burn was executed. It burned for nine minutes as it accelerated Juno on a trajectory to escape Earth’s orbit. From there, the Centaur engine separated from the spacecraft and Juno was on its own. Juno unfurled her solar panels and settled into a five-year journey to her mythical partner.

Juno underwent a series of deep space maneuvers that brought it back near Earth, two years and two months into its voyage. By now, Juno had already traveled 1.6 billion kilometers (994 million miles). Juno came within 559 kilometers (347 miles) of Earth, borrowing our planet’s gravity to boost its speed with an additional 3.9 kilometers per second (8,800 miles per hour). By the time Juno reaches Jupiter, it will have traveled more than 2,800 million kilometers (1.7 billion miles).

While near Earth, Juno did more than just steal some of our velocity. Juno’s science team activated a number of the spacecraft’s instruments and pointed them at Earth, acting as a sort of dress rehearsal for Jupiter.

Juno will be the second spacecraft to orbit and study Jupiter, preceded by the Galileo mission that performed from 1989 to 2003.

At Jupiter

Artist's concept art of Juno at Jupiter

Artist’s concept art of Juno at Jupiter – Credit: NASA/JPL-Caltech

Once Juno arrives at Jupiter on July 4, 2016, it will begin conducting its primary mission objectives. Juno will orbit Jupiter in a highly-elliptical orbit that will take it sweeping in close to the planet over one of its poles, zipping past the other pole in about two hours, before heading out beyond the orbit of Jupiter’s moon Callisto, repeating every 14 days.

Juno is loaded with instruments that will measure the oxygen and hydrogen ratios in Jupiter’s atmosphere, determine the mass of Jupiter’s core, map the gas giant’s magnetic and gravitational fields, and other important observations and experiments. These will allow us to determine how Jupiter formed, determine its structure below the clouds, and establish the source of the planet’s magnetic field.

JunoCam

Juno is also equipped with a visible light camera named JunoCam. Due to Jupiter’s damaging radiation and magnetic fields, JunoCam is only expected to operate for about 7 or 8 orbits; however, while it’s alive it’s expected to produce some fantastic images. Its specific targets will include Jupiter’s polar region and lower-latitude cloud belts, and will boast a resolution of 15 kilometers (9.3 miles) per pixel.

One of the best things about JunoCam is its strong emphasis on education and public outreach. For months now, a JunoCam website has been accepting images of Jupiter captured by amateur astronomers. These images will be publicly discussed during the next couple of months before a round of voting occurs to select the locations on Jupiter for JunoCam to image. Once the images have been captured and sent to Earth, the raw data will be posted on the JunoCam website for anyone to process and share.

Stay Tuned

If you want to stay up-to-date with the mission, you can watch the program page or follow the Twitter account below:

While you’re at it, you should follow the 46BLYZ Twitter account as well! Stay informed on Juno, and everything else space related.

Galileo Spacecraft: First Orbiter of Jupiter

Artist rendering of Galileo arriving at Jupiter

Artist rendering of Galileo arriving at Jupiter – Credit: NASA

Space Shuttle Atlantis carried a special payload during its STS-34 mission. Commander Don Williams and crew transported the Galileo spacecraft into Earth orbit, from which point it was launched on a years-long voyage to Jupiter. Galileo would become the first spacecraft to orbit an outer planet and would go on to reveal fascinating views of the gas giant and its moons, as well as make monumental discoveries about the nature of the Jovian system.


Quick Facts:

  • Launch Date: October 18, 1989, Shuttle Atlantis STS-34
  • Primary Mission: October ’89 to December ’97.
  • Extended Missions: 3, from ’97 to ’03.
  • Number of Jupiter orbits: 34
  • Total distance traveled during mission: 4,631,778,000 km (approx 2.8 billion miles)
  • Mission End: September 21, 2003

Getting Galileo to Jupiter

Work on the Galileo craft began in 1977, after the exploration of Jupiter was listed as the number one priority in the Planetary Science Decadal Survey published in 1968. Fly-bys of the massive planet were conducted by the twin Pioneer 10 and 11 and Voyager 1 and 2 spacecrafts, but Galileo was set to do more than just perform a fly-by. It would launch an instrument-laden probe into Jupiter’s atmosphere, and then continue to orbit the planet for years. This mission would provide knowledge of the Jupiter system that could hardly even be imagined.

Galileo deploying from Shuttle Atlantis

Galileo deploying from Shuttle Atlantis – Credit: NASA

Galileo suffered a number of postponements. The first planned launch was to be from Space Shuttle Columbia in 1982, but development delays in the Space Shuttle program made that early of a launch unfeasible. The upside is that this gave the Galileo developers more time to work on the probe. Further planned launches and postponements occurred in 1984, 1985, and 1986.

As we all know, 1986 was the year of the Challenger disaster. Galileo would be put on hold during the 32-month hiatus that followed the tragedy, as every detail of the Shuttle program was examined and made safer. Galileo was originally planned to be attached to a liquid hydrogen-fueled Centaur-G booster; however, new safety protocols following Challenger prohibited the booster from being carried in the Space Shuttle’s payload bay. Mission designers had to reconsider how they would get Galileo from the Shuttle’s low Earth orbit to Jupiter. They decided on employing a solid-fuel Inertial Upper Stage booster (IUS). Whereas the Centaur-G would have propelled Galileo on a short and direct trajectory to Jupiter, the IUS would take longer and also require some technical gravitational slingshot maneuvers to make it to the gas giant.

Galileo was finally launched from Space Shuttle Atlantis, during mission STS-34 on October 18, 1989. From there, its IUS booster was started and it began its unique “VEEGA”, or Venus Earth Earth Gravity Assist, maneuvers.

Galileo spacecraft trajectory

Galileo spacecraft trajectory – Source: NASA

  • Galileo flew by Venus on February 10, 1990 at an altitude of 16,000 km (10,000 miles).
  • It then flew by Earth on December 8, 1990 at an altitude 960 km (597 miles).
  • Its trajectory took it near Asteroid Gaspra on October 29, 1991, coming within 1,601 km (1,000 miles).
  • Then it was back to another Earth fly-by on December 8, 1992, this time at an altitude of only 303 km (188 miles).
  • On its way back towards the outer solar system it flew by Asteroid Ida on August 28, 1993, coming within 2,400 km (1,400 miles) of the asteroid.

On its way to Jupiter, Galileo was positioned perfectly to observe the doomed Comet Shoemaker-Levy 9 as it impacted the planet. Pieces of the comet, having been torn into fragments by Jupiter’s immense tidal forces, impacted Jupiter from July 16 – 22, 1994, on the side facing away from Earth. Fortunately, Galileo had a prime view and was able to record the impact. Earth-based telescopes could only observe the impact sites as they rotated into view a few minutes afterwards.

In July, 1995, Galileo released its atmospheric probe component. For the next five months, the probe and orbiter continued their cruise to Jupiter. On December 7, 1995, Galileo had arrived. The orbiter and probe diverged onto their separate missions.

Atmospheric Probe

On December 7, 1995 Galileo’s atmospheric probe sliced into Jupiter’s atmosphere at 47.6 kilometers per second (106,000 miles per hour). As the atmosphere began to slow the probe, it deployed its drogue and main parachutes and dropped its heat shield to expose its scientific instruments. The probe began recording data and transmitting it up to the main Galileo spacecraft orbiting high above, which then re-transmitted the data to Earth. The probe recorded 58 minutes of data on Jupiter’s weather and atmosphere. Towards the end of its descent, the probe measured wind speeds of 724 kilometers per hour (450 miles per hour). The intense heat and pressure of Jupiter’s atmosphere melted and vaporized the probe less than an hour into its journey through Jupiter’s atmosphere.

Orbiter

While the atmospheric probe’s job was complete, the Galileo orbiter still had years of work left to do. The orbiter received its electric power from two radioisotope thermoelectric generators (RTGs). That may sound complicated, but it’s really quite simple. These RTGs carry the radioactive element plutonium-238. As the plutonium decays, it releases energy in the form of heat. That heat can then be easily turned into electricity through the Seebeck effect. This type of energy generation is long-lasting and reliable, as well as impervious to the cold temperatures and strong radiation fields of the Jupiter system. Galileo carried two of these RTGs, with a combined total of approximately 22.7 kilograms (50 pounds) of plutonium-238. While these radioactive components had been used on previous space missions, Galileo drew extra concern due to it being both carried by the Shuttle as well as the multiple Earth fly-bys. Anti-nuclear activists protested Galileo’s launch, fearing a malfunction could cause radiation poisoning for many thousands of people on Earth. NASA, however, argued that the probability of risk was extremely low.

Jupiter's ring system, as observed by Galileo

Jupiter’s ring system, as observed by Galileo – Credit: NASA/JPL/Cornell University

Galileo conducted slow orbits of Jupiter, approximately 2 months long each. The orbits were elongated, and designed to bring the spacecraft within different distances to Jupiter, which allowed it to sample different areas of the planet’s magnetosphere. These orbits were also designed to bring Galileo and its instruments into close fly-bys of Jupiter’s largest moons. Galileo completed its primary mission on December 7, 1997; however, the craft was still functioning extremely well and was able to continue taking measurements and sending valuable data back to Earth. Its mission was extended three times, operating until 2003.

Volcanic activity on Io, as observed by Galileo

Volcanic activity on Io, as observed by Galileo – Credit: NASA/JPL

The orbiter made several discoveries during its mission:

  • It discovered a possible ocean under Europa’s icy crust
  • Revealed Ganymede’s very own magnetic field, the only moon known to have this feature
  • Made the first observations of ammonia clouds in another planet’s atmosphere
  • It created hundreds of images of Jupiter’s large ‘Galilean moons’: Io, Callisto, Europa, and Ganymede
  • It measured the high levels of volcanic activity on Io

Sagan Criteria for Life

The late astronomer Carl Sagan devised a set of experiments to be conducted by Galileo during its first fly-by of Earth. The purpose of the experiments was to see if life could be easily detected from a spacecraft. The results of the experiments were published by Sagan in 1993, in the scientific journal Nature. The experiments were a success, as Galileo was easily able to detect what are referred to as the ‘Sagan requirements for life’. These include strong absorption of light at the red end of the spectrum (indicative of plant photosynthesis), absorption bands of molecular oxygen (again, indicative of plant life), the detection of methane in the atmosphere (a gas created by either volcanic or biological activity), and the detection of narrowband radio wave transmissions (could indicate a technologically advanced civilization).


By the end of its mission, Galileo had conducted 34 orbits of Jupiter and had made multiple fly-bys of Jupiter’s moons: Io 7 times, Callisto 8 times , Ganymede 8 times, Europa 11 times, and one fly-by of Amalthea.

Due in part to Galileo’s discovery of potential oceans on Europa (and possibly other Jovian moons), the decision was made to end the orbiter’s mission by sending it to the same fate as the atmospheric probe eight years prior. Rather than risk contaminating (with either Earth bacteria or radiation from the RTGs) one of Jupiter’s potentially life-harboring moons, Galileo would be ordered to impact Jupiter. On September 21, 2003, Galileo entered Jupiter’s atmosphere at 48.2 kilometers per second (108,000 mph).

The Galilean Moons: Jupiter's four largest satellites

The Galilean Moons: Jupiter’s four largest satellites – Credit: NASA/JPL/DLR

The total mission cost was approximately $1.4 billion USD, had more than 100 scientist partners from many different countries, and involved the work of more than 800 individuals.

In spite of postponements, an antenna that failed to fully deploy, and a tape recorder malfunction, Galileo performed magnificently. It was a mission that brought us up close and personal with our Solar system’s largest planet and provided us with a much more detailed understanding of the Jovian system. Galileo paved the way for future studies of Jupiter and its moons. Its successor, the Juno orbiter, is currently en route and arriving in July of 2016, and plans are being considered to investigate Europa’s oceans. Like the astronomer that the spacecraft took its name from, Galileo Galilei, this mission revealed new worlds that we previously could only distantly wonder about.

 

Majestic Conjunction

Have you seen the wondrous show that’s been taking place in the night sky recently? Maybe you noticed what appeared to be some especially bright stars, glittering near a crescent Moon. Perhaps you haven’t been looking up at the night sky lately (shame on you) or conditions have been too cloudy to give it a look (I live in a coastal city in Alaska, I feel your pain). Whether you’re looking or not, there’s a fantastic conjunction taking place, starring (pardon the pun!) the Moon, Jupiter, and Venus.

I took the following photo shortly after sunset on February 28, 2012, from within Joshua Tree National Park. Unfortunately, I didn’t have a lens to give me a wider field of view, but the top of a Yucca Plant provides a nice touch.
Moon, Jupiter, and Venus conjunction, labeled.

[Click image for larger and unlabeled version / Credit: Ryan Marquis/46BLYZ]

This cosmic spectacle will continue over the next few days, so get out and enjoy it while you can.

Also in the night sky this month:
While the Moon will have moved away from the planets, Venus and Jupiter will be within three degrees of each other on March 12. That’s approximately the same “width” as three fingertips held at arm’s length… The planets will appear quite close to one another!

Mars also refuses to be left out of this month’s planetary attention. Look for the red planet in the Eastern sky, just a few hours after the sun sets.

Clear skies!