Bakersfield Night Sky – June 4, 2016
By Nick Strobel
Last Saturday, on May 28, the Juno spacecraft that will study Jupiter crossed the Jupiter gravitational boundary, so now Juno feels Jupiter's gravity force more strongly than the sun's gravity. Juno is speeding toward a rendezvous with Jupiter one month from now, on July 4, when Juno's main engine will burn for 35 minutes to slow it down, so it can go into orbit around Jupiter.
Juno will spend almost two years orbiting Jupiter in very elliptical orbits that carry it over Jupiter's poles and getting as close as 3100 miles above the cloud tops as it swings by the largest planet in the solar system. Ultra-precise measurements of Juno's motion will enable us to probe Jupiter down to its center to see if it has a solid planetary core. One set of instruments will probe the layers higher up but below the clouds we can directly see to determine the global structure and motions of the planet's atmosphere. Another set will measure the amount of water and ammonia in Jupiter's atmosphere that will tell us how Jupiter formed. Other instruments will measure various parts of Jupiter's magnetosphere. Juno's polar orbit will enable us to directly sample the charged particles near Jupiter's poles for the first time, as well as, getting the best views of Jupiter's aurorae that are several times the size of the earth.
Unlike the Cassini spacecraft that has been orbiting Saturn and swinging by several of its moons for over a decade, Juno is going to focus only on Jupiter and it will spend less than two years studying Jupiter before it is purposely deorbited and burns up in Jupiter's atmosphere. The intentional ending of the mission is to make sure that there is zero chance of Juno crashing into Jupiter's moon Europa sometime in the far future and contaminating any possible Europan lifeforms with microbes from the earth. Europa is the moon of Jupiter with a deep ocean of liquid water below a thin layer of frozen water at the surface. Europa is probably the place with the best chance of present life existing now beyond the earth in our solar system.
The last few of Juno's 37 orbits around Jupiter will have it travel through the extremely hazardous radiation belts that will eventually fry the electronics. Juno has been designed with the best radiation shielding that can be put on a spacecraft but even the best shielding can protect a spacecraft for only so long. The Juno team wants to be able to intentionally end the mission before the electronic degradation has reached the point where they can no longer control Juno. Also, the intense radiation in the radiation belts will "eat away" the giant solar panels that power the spacecraft. Jupiter is just not a nice, pleasant place to explore! More about Juno can be found at www.missionjuno.swri.edu and nasa.gov .
Next Saturday, June 11, you can view Jupiter from a safe distance through the telescopes of the Kern Astronomical Society at their free public star party at Panorama Park near where Linden Avenue meets Panorama Drive. A map is posted on the KAS website at kernastro.org . On June 11, we will be only nine days from the solstice, so the sun won't set until about 8:10 p.m. Bright Jupiter will be the first starlike object you'll be able to see in the twilight. Jupiter will be about two-thirds the way up in the southwestern sky to the right of the first quarter moon.
Mars and Saturn will be bright "stars" in the south-southeastern sky. As shown in the attached star chart below, Mars will be the distinctively orange-red object among the stars of Libra. Mars will be shrinking in size over the following months as we leave it behind in our faster orbit. Closest approach was at the end of May but it will still be quite large in the KAS telescopes at the June public star party. Yellow-white Saturn will be above the heart of Scorpius, the red supergiant Antares. The name "Antares" means "rival of Mars" because of its color and its brightness but since Mars's closest approach was so recent, Mars easily outshines Antares in our June 2016 sky.
Now, if Antares was as close as Mars, then Antares would win the photon contest. We'd also be vaporized because we'd be inside Antares. If Antares was placed in the middle of the solar system at the sun's position, Antares would extend out to almost the orbit of Jupiter. Antares produces almost 10,000 times as much visible light as the sun and even more energy in the infrared band.
Did you catch the news item about the new inflatable module that was recently deployed on the International Space Station (ISS)? The Bigelow Expandable Activity Module (BEAM) was delivered to the ISS last month on the SpaceX resupply mission and it will be used as another habitable module for the next two years. If BEAM works out as we're hoping it will, that technology will be used for the future human mission to Mars. Expandable modules are lower-mass and lower-volume systems at launch than the regular metal habitats and in space travel, mass and volume are at a premium. I wonder if I can get a BEAM to add another room onto my house.
Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com