Juno and LADEE succeed despite shutdown

NASA's Juno spacecraft has recovered from a recent glitch and another NASA planetary mission has achieved a crucial milestone. Image Credit: NASA

Jim Siegel

While Congress and the White House continued their stalemate that caused a partial shutdown of the federal government and most of NASA, two NASA space probes achieved milestones in pursuit of their ultimate mission goals. Juno, launched two years ago into a counter-intuitive slingshot orbit, flew back near Earth as it proceeds to its destination, the planet Jupiter. In contrast, LADEE (Lunar Atmosphere and Dust Environment Explorer), launched less than a month ago, inserted itself into an orbit around its destination, the moon. (Just for perspective, Jupiter is roughly 2000 times farther from earth than is the moon, and the moon is about 1000 times father from earth than the International Space Station (ISS).

Juno was launched from Space Launch Complex 41 at the Cape Canaveral Air Force Station on August 5, 2011, a few miles from the space shuttle launch pads at adjacent Kennedy Space Center. United Launch Alliance provided the reliable Atlas V rocket, which first entered service more than 10 years ago, lifted the Juno payload free from Earth’s gravitational shackles. Juno has spent the last two years on a single elliptical orbit, in which it looped back to Earth after first traveling out beyond the orbit of Mars. On October 9 Juno swept within 350 miles over South Africa before beginning its 33-month journey to Jupiter. It’s scheduled to arrive there around the 4th of July 2016.

But the near-Earth Maneuver was not without incident, shortly after completing the fly-by Juno went into an unexplained “safe mode” for roughly 48 hours, according to Scott Bolton, principal investigator for the approximately $1.1 billion NASA-funded mission. Apparently the spacecraft powered down all but its most vital functions, but, to the relief of the entire staff, returned online with no residual problems.

Bill Nye the Science Guy, whose recent and unexpected performance on Dancing with the Stars surprised judges and viewers alike, has an interesting YouTube video that explains Juno’s slingshot process.

httpv://youtu.be/3nj_xq8nfxE

Video courtesy of Bill Nye

The spacecraft is to be placed in a polar orbit around Jupiter to study the planet’s composition, gravity field, magnetic field, and polar magnetosphere. Juno will also search for clues about how Jupiter formed, including whether the planet has a rocky core, the amount of water present within the deep atmosphere, and how the planet’s mass is distributed. It will also study Jupiter’s deep winds, which can reach speeds of 384 miles per hour (618 kilometers per hour).

The spacecraft’s name comes from Greco-Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, but his wife, the goddess Juno, was able to peer through the clouds and see Jupiter’s true nature.

“Jupiter is the Rosetta Stone of our solar system,” says Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”

Meanwhile, ground controllers at NASA’s Ames Research Center in California were guiding the LADEE spacecraft through a one-week series of burns to reposition it from a relatively high “parking” orbit around the moon to a lower orbit where it is planned to begin its exploratory work. An October 12 burn positioned LADEE into orbit closely aligned to the Moon’s equator, at an altitude of about 155 miles.

During its nominal 100-day scientific mission, LADEE will continue to circle around the Moon‘s equator, and use instruments aboard the spacecraft to study the lunar exosphere and dust in the Moon’s vicinity. Instruments include a dust detector, a neutral mass spectrometer, and an ultraviolet-visible spectrometer, as well as a technology demonstration consisting of a laser communications terminal.

The roughly $280 million LADEE mission, initially announced as part of NASA’s FY2009 budget, has three major science goals:

Determine the global density, composition, and time variability of the tenuous lunar exosphere before it is perturbed by further human activity.

before it is perturbed by further human activity. Determine if the Apollo astronaut sightings of diffuse emission at tens of kilometers above the surface were sodium glow or dust.

or dust. Document the dust impactor environment (size-frequency) to help guide design engineering for the outpost and also future robotic missions.

The science payload consists of:

Neutral Mass Spectrometer (NMS), that will perform in situ measurements of exospheric species. The instrument has heritage from the SAM instrument on the Mars Science Laboratory .

species. The instrument has heritage from the SAM instrument on the UV-Vis Spectrometer (UVS), that will measure both the dust and exosphere. The instrument has heritage from the UV-Vis spectrometer on the LCROSS mission.

(UVS), that will measure both the dust and exosphere. The instrument has heritage from the UV-Vis spectrometer on the mission. Lunar Dust EXperiment (LDEX), that will directly measure dust. The instrument has heritage from instruments on Galileo, Ulysses and Cassini.

LADEE also carries a technology demonstration payload for testing an optical communication system. The Lunar Laser Communication Demonstration (LLCD) will use a laser to transmit and receive data as pulses of light, much the same as data is transferred in a fiber optic cable, to three ground stations. This method of communication has the potential to provide five times the current data return, as compared to radio frequency communication, from both LADEE and future missions. The technology is a direct predecessor to NASA’s Laser Communication Data Relay (LCDR) satellite due to launch in 2017.

NASA’s planetary missions have fared fairly well considering the woes inflicted on space exploration efforts caused by the shutdown of the U.S. federal government. NASA’s next planned Mars mission, the Mars Atmosphere and Volatile EvolutioN or “MAVEN” mission was kept going via a special exception. This should allow the probe to launch next month.

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