Final Post of the Year: Asteroid Images by Arecibo...

Arecibo Observatory / NASA / NSF

Arecibo Radar Returns with Asteroid Phaethon Images (Press Release - December 22)

After several months of downtime since Hurricane Maria struck the island of Puerto Rico, the Arecibo Observatory Planetary Radar has returned to normal operation, providing the highest-resolution images to date of near-Earth asteroid 3200 Phaethon during its December 2017 close approach to Earth. The radar images, which are subtle at the available resolution, reveal the asteroid is spheroidal (roughly ball-shaped) and has a large concavity, or depression, at least several hundred meters in extent near its equator, and a conspicuous dark, circular feature near one of the poles. Arecibo's radar images of Phaethon have resolutions as fine as about 250 feet (75 meters) per pixel.

"These new observations of Phaethon show it may be similar in shape to asteroid Bennu, the target of NASA's OSIRIS-REx spacecraft, but more than 1,000 Bennus could fit inside of Phaethon," said Patrick Taylor, a Universities Space Research Association (USRA), Columbia, Maryland, scientist and group leader for Planetary Radar at Arecibo Observatory. "The dark feature could be a crater or some other topographic depression that did not reflect the radar beam back to Earth."

Radar images obtained by Arecibo indicate Phaethon has a diameter of about 3.6 miles (6 kilometers) -- roughly 0.6 miles (1 kilometer) larger than previous estimates. Phaethon is the second largest near-Earth asteroid classified as "Potentially Hazardous." Near-Earth objects are classified as potentially hazardous asteroids (PHAs), based on their size and how closely they can approach Earth's orbit.

Tracking and characterizing PHAs is a primary mission of NASA's Planetary Defense Coordination Office. Radar is a powerful technique for studying asteroid sizes, shapes, rotation, surface features and roughness, and for more precise determination of their orbital path, when they pass relatively close to Earth.

"Arecibo is an important global asset, crucial for planetary defense work because of its unique capabilities," said Joan Schmelz of USRA and deputy director of Arecibo Observatory. "We have been working diligently to get it back up and running since Hurricane Maria devastated Puerto Rico."

The Arecibo Observatory has the most powerful astronomical radar system on Earth. On Sept. 20, the telescope suffered minor structural damage when Maria, the strongest hurricane to hit the island since 1928, made landfall. Some days after the storm, the observatory resumed radio astronomy observations, while also serving as a base for relief efforts to surrounding communities. Radar observations, which require high power and diesel fuel for generators at the site, resumed operations in early December after commercial power returned to the observatory and the generators could then be used exclusively for the radar.

Asteroid 3200 Phaethon was discovered on Oct. 11, 1983, by NASA's Infrared Astronomical Satellite (IRAS), and the planetary dust that produces the annual Geminid meteor shower originates from this asteroid. Observations of Phaethon were conducted at Arecibo from Dec. 15 through 19, 2017, using the NASA-funded planetary radar system. At time of closest approach on Dec. 16 at 3 p.m. PST (6 p.m. EST, 11 p.m. UTC) the asteroid was about 6.4 million miles (10.3 million kilometers) away, or about 27 times the distance from Earth to the moon. The encounter is the closest the asteroid will come to Earth until 2093, but it came a little closer in 1974 and about half this distance back in 1931 before its existence was known.

The Arecibo Planetary Radar Program is funded by NASA's Near-Earth Object Observations Program through a grant to Universities Space Research Association (USRA), from the Near-Earth Object Observations program. The Arecibo Observatory is a facility of the National Science Foundation operated under cooperative agreement by SRI International, USRA, and Universidad Metropolitana.

NASA's Planetary Defense Coordination Office is responsible for finding, tracking and characterizing potentially hazardous asteroids and comets coming near Earth, issuing warnings about possible impacts, and assisting coordination of U.S. government response planning, should there be an actual impact threat.

Source: Jet Propulsion Laboratory

Images of the Day: More Cool Pics of the Dragonfly...

NASA

MERRY CHRISTMAS, EVERYONE! Just thought I'd mark today's joyous occasion (unless of course, you live here in the United States and constantly read about politics) by sharing these images I found online of the Dragonfly rotorcraft that will hopefully emerge victorious when NASA announces its fourth New Frontiers space mission in mid-2019. The two screenshots directly below, in particular, totally hype me up in terms of the type of vehicle that will hopefully fly through Titan's atmosphere when it arrives at Saturn's largest moon in 2034 after launching from Florida in 2025. These screenshots came from this fascinating YouTube video, while the video itself was posted on the main mission website for Dragonfly.

All I can say is, next decade could prove to be an exciting one for space aficionados like myself who wish to see another spacecraft join the Europa Clipper in studying an intriguing ocean moon orbiting a gas giant in our solar system. But we'll find out what NASA ultimately selects less than two years from now... Happy Holidays!


Johns Hopkins University - Applied Physics Laboratory


Johns Hopkins University - Applied Physics Laboratory


APL / Michael Carroll


APL / Michael Carroll


Johns Hopkins University - Applied Physics Laboratory

The Four Conservatives of the Apocalypse...

This summary is not available. Please click here to view the post.

The Little Theater...

Seven years ago tonight, I went to the FOX Studios in Century City to attend a screening for a movie (which shall remain unnamed) that was released in theaters nationwide in spring of 2011. The screening took place inside the Little Theater...shown in the pics above and below this entry. The reason why I bring this up is that this screening would set up a chain of events that would profoundly affect my life—but not in a positive way. If I could go back to that night, well, I wouldn't have changed a thing. It was what took place less than two weeks after this screening occurred (around New Year's Day) that mistakes were made that would put me in the predicament I'm in now. Sorry for this extremely cryptic Blog entry. But I will tell you that the film I saw in the Little Theater was really good! I'll leave it at that.

And if any of you knows someone who goes by the online screenname "Saadizzle," kick his ass. Destroy him if you have to! Carry on.

I'm VERY Excited for the Dragonfly Mission to Titan!

NASA

NASA Invests in Concept Development for Missions to Comet, Saturn Moon Titan (Press Release)

NASA has selected two finalist concepts for a robotic mission planned to launch in the mid-2020s: a comet sample return mission and a drone-like rotorcraft that would explore potential landing sites on Saturn’s largest moon, Titan.

The agency announced the concepts Wednesday, following an extensive and competitive peer review process. The concepts were chosen from 12 proposals submitted in April under a New Frontiers program announcement of opportunity.

“This is a giant leap forward in developing our next bold mission of science discovery,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “These are tantalizing investigations that seek to answer some of the biggest questions in our solar system today.”

The finalists are:

Comet Astrobiology Exploration Sample Return (CAESAR)

The CAESAR mission seeks to return a sample from 67P/Churyumov-Gerasimenko, a comet that was successfully explored by the European Space Agency’s Rosetta spacecraft, to determine its origin and history. Led by Steve Squyres of Cornell University in Ithaca, New York, CAESAR would be managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Dragonfly

Dragonfly is a drone-like rotorcraft that would explore the prebiotic chemistry and habitability of dozens of sites on Saturn’s moon Titan, an ocean world in our solar system. Elizabeth Turtle from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, is the lead investigator, with APL providing project management.

The CAESAR and Dragonfly missions will receive funding through the end of 2018 to further develop and mature their concepts. NASA plans to select one of these investigations in the spring of 2019 to continue on to subsequent mission phases.

The selected mission will be the fourth in NASA’s New Frontiers portfolio, a series of principal investigator-led planetary science investigations that fall under a development cost cap of approximately $850 million. Its predecessors are the New Horizons mission to Pluto and a Kuiper Belt Object known as 2014 MU69, the Juno mission to Jupiter, and OSIRIS-REx, which will rendezvous with and return a sample of the asteroid Bennu.

NASA also announced the selection of two mission concepts that will receive technology development funds to prepare them for future mission competitions.

The concepts selected for technology development are:

Enceladus Life Signatures and Habitability (ELSAH)

The ELSAH mission concept will receive funds to develop cost-effective techniques that limit spacecraft contamination and thereby enable life detection measurements on cost-capped missions. The principal investigator is Chris McKay of NASA’s Ames Research Center in California’s Silicon Valley, and the managing NASA center is Goddard.

Venus In situ Composition Investigations (VICI)

Led by Lori Glaze at Goddard, the VICI mission concept will further develop the Venus Element and Mineralogy Camera to operate under the harsh conditions on Venus. The instrument uses lasers on a lander to measure the mineralogy and elemental composition of rocks on the surface of Venus.

The call for concepts was limited to six mission themes: comet surface sample return, lunar south pole-Aitken Basin sample return, ocean worlds (Titan and/or Enceladus), Saturn probe, Trojan asteroid tour and rendezvous, and Venus in situ explorer.

New Frontiers Program investigations address NASA’s planetary science objectives as described in the 2014 NASA Strategic Plan and the 2014 NASA Science Plan. The program is managed by the Planetary Missions Program Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Planetary Science Division in Washington.

Source: NASA.Gov

****


NASA

A Memorable Night for the Lakers: The Mamba Is Immortalized...

Los Angeles Lakers

Much props to Kobe Bryant for taking his place among his fellow Laker greats at STAPLES Center tonight. During the halftime ceremony of the Lakers-Golden State Warriors game in Los Angeles today (the Warriors won in overtime, 116-114), Kobe, his family, his former teammates (such as Shaquille O'Neal, Rick Fox, Derek Fisher and Gary Payton) and some former rivals (Allen Iverson, who took on Kobe and Co. when L.A. played against the Philadelphia 76ers during the 2001 NBA Finals, was at the game) were on-hand to watch as two black panels near the ceiling rafters descended to reveal the two jersey numbers, #8 and #24, that Bryant wore from 1996 to last year. It was a bittersweet moment...and as Lakers president Jeanie Buss pointed out, was all the more sweeter considering that Kobe won five titles and earned his spot as a Los Angeles sports legend by staying with the Lake Show for all 20 years of his career. That must have slightly stung for the Warriors' Kevin Durant (whose team watched the ceremony from the sideline)—who got flack for leaving the Oklahoma City Thunder to win a championship with Golden State last season.


Los Angeles Lakers

Can't wait till a bronze statue of the Black Mamba is eventually put up outside of STAPLES Center. Much like Shaq's statue, I'll drive to L.A. to take a photo of the metallic ode to KB8 / KB24's greatness once it's on display. Though the big question is: Which jersey number will be represented on Kobe's statue? Happy Monday!


Los Angeles Lakers


NBA

****

#Ko8e24 @KobeBryant's Ultimate #8v24 @Lakers #NBAMixtape! https://t.co/Dyhw8Hgq0u

— NBA (@NBA) December 18, 2017

Kepler Update: Thanks To Google, An 8th Exoplanet Is Found Orbiting Kepler-90...

NASA / Ames Research Center / Wendy Stenzel

Artificial Intelligence, NASA Data Used to Discover Eighth Planet Circling Distant Star (News Release - December 14)

Our solar system now is tied for most number of planets around a single star, with the recent discovery of an eighth planet circling Kepler-90, a Sun-like star 2,545 light years from Earth. The planet was discovered in data from NASA's Kepler Space Telescope.

The newly-discovered Kepler-90i - a sizzling hot, rocky planet that orbits its star once every 14.4 days - was found using machine learning from Google. Machine learning is an approach to artificial intelligence in which computers "learn." In this case, computers learned to identify planets by finding in Kepler data instances where the telescope recorded changes in starlight caused by planets beyond our solar system, known as exoplanets.

"Just as we expected, there are exciting discoveries lurking in our archived Kepler data, waiting for the right tool or technology to unearth them," said Paul Hertz, director of NASA's Astrophysics Division in Washington. "This finding shows that our data will be a treasure trove available to innovative researchers for years to come."

The discovery came about after researchers Christopher Shallue and Andrew Vanderburg trained a computer to learn how to identify exoplanets in the light readings recorded by Kepler - the miniscule change in brightness captured when a planet passed in front of, or transited, a star. Inspired by the way neurons connect in the human brain, this artificial "neural network" sifted through Kepler data and found weak transit signals from a previously-missed eighth planet orbiting Kepler-90, in the constellation Draco.

Machine learning has previously been used in searches of the Kepler database, and this continuing research demonstrates that neural networks are a promising tool in finding some of the weakest signals of distant worlds.

Other planetary systems probably hold more promise for life than Kepler-90. About 30 percent larger than Earth, Kepler-90i is so close to its star that its average surface temperature is believed to exceed 800 degrees Fahrenheit, on par with Mercury. Its outermost planet, Kepler-90h, orbits at a similar distance to its star as Earth does to the Sun.

"The Kepler-90 star system is like a mini version of our solar system. You have small planets inside and big planets outside, but everything is scrunched in much closer," said Vanderburg, a NASA Sagan Postdoctoral Fellow and astronomer at the University of Texas at Austin.

Shallue, a senior software engineer with Google's research team Google AI, came up with the idea to apply a neural network to Kepler data. He became interested in exoplanet discovery after learning that astronomy, like other branches of science, is rapidly being inundated with data as the technology for data collection from space advances.

"In my spare time, I started Googling for 'finding exoplanets with large data sets' and found out about the Kepler mission and the huge data set available," said Shallue. "Machine learning really shines in situations where there is so much data that humans can't search it for themselves."

Kepler's four-year dataset consists of 35,000 possible planetary signals. Automated tests, and sometimes human eyes, are used to verify the most promising signals in the data. However, the weakest signals often are missed using these methods. Shallue and Vanderburg thought there could be more interesting exoplanet discoveries faintly lurking in the data.

First, they trained the neural network to identify transiting exoplanets using a set of 15,000 previously vetted signals from the Kepler exoplanet catalogue. In the test set, the neural network correctly identified true planets and false positives 96 percent of the time. Then, with the neural network having "learned" to detect the pattern of a transiting exoplanet, the researchers directed their model to search for weaker signals in 670 star systems that already had multiple known planets. Their assumption was that multiple-planet systems would be the best places to look for more exoplanets.

"We got lots of false positives of planets, but also potentially more real planets," said Vanderburg. "It's like sifting through rocks to find jewels. If you have a finer sieve then you will catch more rocks but you might catch more jewels, as well."

Kepler-90i wasn't the only jewel this neural network sifted out. In the Kepler-80 system, they found a sixth planet. This one, the Earth-sized Kepler-80g, and four of its neighboring planets form what is called a resonant chain - where planets are locked by their mutual gravity in a rhythmic orbital dance. The result is an extremely stable system, similar to the seven planets in the TRAPPIST-1 system.

Their research paper reporting these findings has been accepted for publication in The Astronomical Journal. Shallue and Vanderburg plan to apply their neural network to Kepler's full set of more than 150,000 stars.

Kepler has produced an unprecedented data set for exoplanet hunting. After gazing at one patch of space for four years, the spacecraft now is operating on an extended mission and switches its field of view every 80 days.

"These results demonstrate the enduring value of Kepler's mission," said Jessie Dotson, Kepler's project scientist at NASA's Ames Research Center in California's Silicon Valley. "New ways of looking at the data - such as this early-stage research to apply machine learning algorithms - promise to continue to yield significant advances in our understanding of planetary systems around other stars. I'm sure there are more firsts in the data waiting for people to find them."

Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate in Washington. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. This work was performed through the Carl Sagan Postdoctoral Fellowship Program executed by the NASA Exoplanet Science Institute.

Source: Jet Propulsion Laboratory

****

The FCC Has Repealed Net Neutrality...

Almost two weeks after Republicans in the U.S. Senate approved a shitty tax bill that would add around $1.4 trillion to the national deficit and take health coverage away from 13 million Americans, another Trump era-related abomination took place today when the Federal Communications Commission (FCC) voted to repeal net neutrality. What that means is, internet providers like Verizon and Comcast will have the ability to block content that folks look at on the Web...and even potentially force Americans to pay to use currently-free online services like Google, YouTube and Twitter. On the plus side though, Congress and the nation's courts have the ability to block this repeal from taking effect. The downside though, is that Congress is led by the Republicans...and it's the corporations (like Verizon and Comcast) and the GOP members who receive donations from them who'll benefit the most from the end of net neutrality. So once again, America's First Amendment principles are threatened by conservatives using Donald Trump's so-called presidency to enhance their greed at the expense of ordinary citizens throughout the United States.

All I can say is, Eminem needs to write a new rap song about the FCC and its corrupt chairman, Ajit Pai—telling them to go fuck themselves. Hell, include the GOP and Trump in his song while he's at it. November of 2018 can't come soon enough... We need the Democrats to regain control of the House and Senate and punish folks like Pai for their obstinacy and insolence towards this great country. That is all.

Dawn Update: New Spots on a Dwarf Planet's Surface...

NASA / JPL - Caltech / UCLA / MPS / DLR / IDA / PSI

Bright Areas on Ceres Suggest Geologic Activity (Press Release)

If you could fly aboard NASA's Dawn spacecraft, the surface of dwarf planet Ceres would generally look quite dark, but with notable exceptions. These exceptions are the hundreds of bright areas that stand out in images Dawn has returned. Now, scientists have a better sense of how these reflective areas formed and changed over time -- processes indicative of an active, evolving world.

"The mysterious bright spots on Ceres, which have captivated both the Dawn science team and the public, reveal evidence of Ceres' past subsurface ocean, and indicate that, far from being a dead world, Ceres is surprisingly active. Geological processes created these bright areas and may still be changing the face of Ceres today," said Carol Raymond, deputy principal investigator of the Dawn mission, based at NASA's Jet Propulsion Laboratory in Pasadena, California. Raymond and colleagues presented the latest results about the bright areas at the American Geophysical Union meeting in New Orleans on Tuesday, Dec. 12.

Different Kinds of Bright Areas

Since Dawn arrived in orbit at Ceres in March 2015, scientists have located more than 300 bright areas on Ceres. A new study in the journal Icarus, led by Nathan Stein, a doctoral researcher at Caltech in Pasadena, California, divides Ceres' features into four categories.

The first group of bright spots contains the most reflective material on Ceres, which is found on crater floors. The most iconic examples are in Occator Crater, which hosts two prominent bright areas. Cerealia Facula, in the center of the crater, consists of bright material covering a 6-mile-wide (10-kilometer-wide) pit, within which sits a small dome. East of the center is a collection of slightly less reflective and more diffuse features called Vinalia Faculae. All the bright material in Occator Crater is made of salt-rich material, which was likely once mixed in water. Although Cerealia Facula is the brightest area on all of Ceres, it would resemble dirty snow to the human eye.

More commonly, in the second category, bright material is found on the rims of craters, streaking down toward the floors. Impacting bodies likely exposed bright material that was already in the subsurface or had formed in a previous impact event.

Separately, in the third category, bright material can be found in the material ejected when craters were formed.

The mountain Ahuna Mons gets its own fourth category -- the one instance on Ceres where bright material is unaffiliated with any impact crater. This likely cryovolcano, a volcano formed by the gradual accumulation of thick, slowly flowing icy materials, has prominent bright streaks on its flanks.

Over hundreds of millions of years, bright material has mixed with the dark material that forms the bulk of Ceres' surface, as well as debris ejected during impacts. That means billions of years ago, when Ceres experienced more impacts, the dwarf planet's surface likely would have been peppered with thousands of bright areas.

"Previous research has shown that the bright material is made of salts, and we think subsurface fluid activity transported it to the surface to form some of the bright spots," Stein said.

The Case of Occator

Why do the different bright areas of Occator seem so distinct from one another? Lynnae Quick, a planetary geologist at the Smithsonian Institution in Washington, has been delving into this question.

The leading explanation for what happened at Occator is that it could have had, at least in the recent past, a reservoir of salty water beneath it. Vinalia Faculae, the diffuse bright regions to the northeast of the crater's central dome, could have formed from a fluid driven to the surface by a small amount of gas, similar to champagne surging out of its bottle when the cork is removed.

In the case of the Vinalia Faculae, the dissolved gas could have been a volatile substance such as water vapor, carbon dioxide, methane or ammonia. Volatile-rich salty water could have been brought close to Ceres' surface through fractures that connected to the briny reservoir beneath Occator. The lower pressure at Ceres' surface would have caused the fluid to boil off as a vapor. Where fractures reached the surface, this vapor could escape energetically, carrying with it ice and salt particles and depositing them on the surface.

Cerealia Facula must have formed in a somewhat different process, given that it is more elevated and brighter than Vinalia Faculae. The material at Cerealia may have been more like an icy lava, seeping up through the fractures and swelling into a dome. Intermittent phases of boiling, similar to what happened when Vinalia Faculae formed, may have occurred during this process, littering the surface with ice and salt particles that formed the Cerealia bright spot.

Quick's analyses do not depend on the initial impact that formed Occator. However, the current thinking among Dawn scientists is that when a large body slammed into Ceres, excavating the 57-mile-wide (92-kilometer-wide) crater, the impact may have also created fractures through which liquid later emerged.

"We also see fractures on other solar system bodies, such as Jupiter's icy moon Europa," Quick said. "The fractures on Europa are more widespread than the fractures we see at Occator. However, processes related to liquid reservoirs that might exist beneath Europa's cracks today could be used as a comparison for what may have happened at Occator in the past."

As Dawn continues the final phase of its mission, in which it will descend to lower altitudes than ever before, scientists will continue learning about the origins of the bright material on Ceres and what gave rise to the enigmatic features in Occator.

The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

Source: Jet Propulsion Laboratory

****

Photos of the Day: Tonight's Supermoon...

Just thought I'd share these pics that I took of tonight's Supermoon...also known as the Frost Moon, Cold Moon, Long Night Moon, Moon before Yule and the Strawberry Moon (as seen from the Southern Hemisphere, that is). This is the first of three consecutive Supermoons to grace the skies over the next two months; another Supermoon will take place on January 1st, while the third one—which will also be a total lunar eclipse that's visible over much of the U.S.—occurs on January 31st. Sweeet. In regards to the settings I employed on my Nikon D3300 DSLR camera for these images, I selected ISO 200 for the exposure, placed the shutter speed at 1/800, had the f-stop at 6.3 and used a Nikkor 70-300mm autofocus zoom lens that I got for my birthday this year. How sweet again. I'm totally lookin' forward to the lunar eclipse next month! Have a great week ahead.

Voyager 1 Update: A Significant Development for the Interstellar Spacecraft...

NASA / JPL - Caltech

Voyager 1 Fires Up Thrusters After 37 Years (News Release)

If you tried to start a car that's been sitting in a garage for decades, you might not expect the engine to respond. But a set of thrusters aboard the Voyager 1 spacecraft successfully fired up Wednesday after 37 years without use.

Voyager 1, NASA's farthest and fastest spacecraft, is the only human-made object in interstellar space, the environment between the stars. The spacecraft, which has been flying for 40 years, relies on small devices called thrusters to orient itself so it can communicate with Earth. These thrusters fire in tiny pulses, or "puffs," lasting mere milliseconds, to subtly rotate the spacecraft so that its antenna points at our planet. Now, the Voyager team is able to use a set of four backup thrusters, dormant since 1980.

"With these thrusters that are still functional after 37 years without use, we will be able to extend the life of the Voyager 1 spacecraft by two to three years," said Suzanne Dodd, project manager for Voyager at NASA's Jet Propulsion Laboratory, Pasadena, California.

Since 2014, engineers have noticed that the thrusters Voyager 1 has been using to orient the spacecraft, called "attitude control thrusters," have been degrading. Over time, the thrusters require more puffs to give off the same amount of energy. At 13 billion miles from Earth, there's no mechanic shop nearby to get a tune-up.

The Voyager team assembled a group of propulsion experts at NASA's Jet Propulsion Laboratory, Pasadena, California, to study the problem. Chris Jones, Robert Shotwell, Carl Guernsey and Todd Barber analyzed options and predicted how the spacecraft would respond in different scenarios. They agreed on an unusual solution: Try giving the job of orientation to a set of thrusters that had been asleep for 37 years.

“The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters," said Jones, chief engineer at JPL.

In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and important moons of each. To accurately fly by and point the spacecraft's instruments at a smorgasbord of targets, engineers used "trajectory correction maneuver,” or TCM, thrusters that are identical in size and functionality to the attitude control thrusters, and are located on the back side of the spacecraft. But because Voyager 1's last planetary encounter was Saturn, the Voyager team hadn't needed to use the TCM thrusters since November 8, 1980. Back then, the TCM thrusters were used in a more continuous firing mode; they had never been used in the brief bursts necessary to orient the spacecraft.

All of Voyager's thrusters were developed by Aerojet Rocketdyne. The same kind of thruster, called the MR-103, flew on other NASA spacecraft as well, such as Cassini and Dawn.

On Tuesday, Nov. 28, 2017, Voyager engineers fired up the four TCM thrusters for the first time in 37 years and tested their ability to orient the spacecraft using 10-millisecond pulses. The team waited eagerly as the test results traveled through space, taking 19 hours and 35 minutes to reach an antenna in Goldstone, California, that is part of NASA's Deep Space Network.

Lo and behold, on Wednesday, Nov. 29, they learned the TCM thrusters worked perfectly -- and just as well as the attitude control thrusters.

“The Voyager team got more excited each time with each milestone in the thruster test. The mood was one of relief, joy and incredulity after witnessing these well-rested thrusters pick up the baton as if no time had passed at all," said Barber, a JPL propulsion engineer.

The plan going forward is to switch to the TCM thrusters in January. To make the change, Voyager has to turn on one heater per thruster, which requires power -- a limited resource for the aging mission. When there is no longer enough power to operate the heaters, the team will switch back to the attitude control thrusters.

The thruster test went so well, the team will likely do a similar test on the TCM thrusters for Voyager 2, the twin spacecraft of Voyager 1. The attitude control thrusters currently used for Voyager 2 are not yet as degraded as Voyager 1's, however.

Voyager 2 is also on course to enter interstellar space, likely within the next few years.

The Voyager spacecraft were built by JPL, which continues to operate both. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.

Source: NASA.Gov