On September 6, 2013, NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched on board a Minotaur V rocket at NASA's Wallops Flight Facility. The LADEE mission's goal was to orbit the moon to gather detailed information about the lunar atmosphere, conditions near the surface, and environmental influences on lunar dust. The data collected from LADEE is being used to reveal the composition of, and variations in, the lunar atmosphere, as well as give insight into the amount of lunar dust in the atmosphere. The LADEE mission ended on April 17, 2014, with a planned impact with the surface of the moon.
LADEE News and Features
NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE)- pronounced "laddie" - was a robotic mission that orbited the moon to gather detailed information about the structure and composition of the thin lunar atmosphere, and determine whether dust is lofted into the lunar sky. A thorough understanding of these characteristics of our nearest celestial neighbor will help researchers understand other bodies in the solar system, such as large asteroids, Mercury, and the moons of outer planets.
The LADEE spacecraft's modular common spacecraft bus, or body, innovated away from custom designs and transitioned toward multi-use designs and assembly-line production, which could drastically reduce the cost of spacecraft development, just as the Ford Model T did for automobiles. NASA's Ames Research Center designed, developed, built, and tested the spacecraft and managed mission operations.
The LADEE spacecraft's modular common spacecraft bus, or body, innovated away from custom designs and transitioned toward multi-use designs and assembly-line production, which could drastically reduce the cost of spacecraft development, just as the Ford Model T did for automobiles. NASA's Ames Research Center designed, developed, built, and tested the spacecraft and managed mission operations.
LADEE Project Scientist Update: The Legacy Lives On!
April 22, 2014
NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft has impacted the Moon, capping an extremely successful operational mission. Science analysis will continue for months, as the science teams churn through the data and write papers about their findings. So LADEE is gone, but its science legacy lives on!
LADEE ran its science instruments almost non-stop right up to impact the evening of April 17, 2014, in an effort to gather as much low-altitude data as possible. Further study of the returned data will reveal what the instruments saw at these amazingly low orbits, just a few kilometers above the surface. Early results suggest that LADEE was low enough to see some new things, including increased dust density and possibly new atmospheric species. In an incredible race with time, LADEE’s Real Time Operations team queued and downloaded all science files just minutes prior to LADEE's impact.
As the clock was running out on the LADEE mission, we took advantage of an opportunity to replicate observations by the Apollo astronauts more than 40 years ago. (We hinted at this in an earlier update). We used one of the star tracker cameras to gaze out over the Moon's horizon, while LADEE was in the deep darkness of the lunar night and over the far side where no Earthshine can reach.
A series of star tracker images taken by LADEE Saturday, April 12. The lunar horizon is ahead, a few minutes before orbital sunrise.
Image Credit:
NASA Ames
In the minutes before orbital sunrise, when LADEE emerged from shadow into sunlight, we commanded the spacecraft to take a series of images. We wanted to see the same scene the astronauts saw, with the sun just below the horizon. In this configuration, we could view anything that might scatter sunlight. On Earth, "rosy-fingered dawn" paints the sky prior to sunrise because aerosols and dust particles suspended in the atmosphere scatter the sunlight. With the sun below the horizon, the reflected and scattered light makes the sunrise glow for an observer to see in the dark shadow beyond. However, the very low dust densities that LADEE's Lunar Dust Experiment (LDEX) measured should not produce such a sunrise glow – there were just too few particles along the line of sight to scatter measurable light. Yet some Apollo astronauts reported a pre–sunrise glow and even rays of light, as if the sun was shining through notches of the lunar mountains, and the light was scattered by…something. Could LADEE spot this?
Shown here is a series of images taken on one such occasion, Saturday, April 12. The series begins with LADEE viewing the lunar horizon ahead, a few minutes before orbital sunrise. At this position, there is already a glow in the sky above the completely dark surface of the Moon (right), though the sun is many degrees below the horizon. LADEE’s orbital motion makes the stars appear to move to the left. The same motion brings the sun closer to the horizon ahead and the glow gets brighter. In fact, the glow becomes so bright, parts of the image are saturated. Finally, sunrise fully saturates the camera image. This sequence is the closest thing to the astronaut's orbital viewpoint that LADEE could provide!
A good example of zodiacal light.
Image Credit:
Copyright: Yuri Beletsky (ESO)
The shape of this glow is familiar; we've seen it before. The images reveal a phenomenon that even we can see during a dark, clear night after sunset here on Earth – the zodiacal light. What is zodiacal light? It is the scattered sunlight from billions upon billions of dust grains, not at the Moon, but in the innermost reaches of the solar system. The origin of this dust appears to be comets, which shed gas and dust in their orbital progress around the sun. The lenticular shape of the zodiacal light, seen in the LADEE star tracker images, results from the tendency of the dust to be more concentrated near the orbital plane of the planets.
Unlike Eugene Cernan's sketches from his vantage point in the Apollo 17 command module, America, LADEE saw no rays or other strange features - just good old zodiacal light, plus possibly the outer fringes of the sun's corona. LADEE took several sequences of these orbital sunrise images, and for now, nothing has shown up that clearly is lunar in origin. In the coming weeks and months, we'll carefully analyze these images, and perhaps something related to levitated lunar dust will emerge.
But it sure looks like sunrise is just as impressive from LADEE's vantage point as it is to us on Earth.
LADEE Project Scientist Update: The Legacy Lives On!
April 22, 2014
NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft has impacted the Moon, capping an extremely successful operational mission. Science analysis will continue for months, as the science teams churn through the data and write papers about their findings. So LADEE is gone, but its science legacy lives on!
LADEE ran its science instruments almost non-stop right up to impact the evening of April 17, 2014, in an effort to gather as much low-altitude data as possible. Further study of the returned data will reveal what the instruments saw at these amazingly low orbits, just a few kilometers above the surface. Early results suggest that LADEE was low enough to see some new things, including increased dust density and possibly new atmospheric species. In an incredible race with time, LADEE’s Real Time Operations team queued and downloaded all science files just minutes prior to LADEE's impact.
As the clock was running out on the LADEE mission, we took advantage of an opportunity to replicate observations by the Apollo astronauts more than 40 years ago. (We hinted at this in an earlier update). We used one of the star tracker cameras to gaze out over the Moon's horizon, while LADEE was in the deep darkness of the lunar night and over the far side where no Earthshine can reach.
A series of star tracker images taken by LADEE Saturday, April 12. The lunar horizon is ahead, a few minutes before orbital sunrise.
Image Credit:
NASA Ames
In the minutes before orbital sunrise, when LADEE emerged from shadow into sunlight, we commanded the spacecraft to take a series of images. We wanted to see the same scene the astronauts saw, with the sun just below the horizon. In this configuration, we could view anything that might scatter sunlight. On Earth, "rosy-fingered dawn" paints the sky prior to sunrise because aerosols and dust particles suspended in the atmosphere scatter the sunlight. With the sun below the horizon, the reflected and scattered light makes the sunrise glow for an observer to see in the dark shadow beyond. However, the very low dust densities that LADEE's Lunar Dust Experiment (LDEX) measured should not produce such a sunrise glow – there were just too few particles along the line of sight to scatter measurable light. Yet some Apollo astronauts reported a pre–sunrise glow and even rays of light, as if the sun was shining through notches of the lunar mountains, and the light was scattered by…something. Could LADEE spot this?
Shown here is a series of images taken on one such occasion, Saturday, April 12. The series begins with LADEE viewing the lunar horizon ahead, a few minutes before orbital sunrise. At this position, there is already a glow in the sky above the completely dark surface of the Moon (right), though the sun is many degrees below the horizon. LADEE’s orbital motion makes the stars appear to move to the left. The same motion brings the sun closer to the horizon ahead and the glow gets brighter. In fact, the glow becomes so bright, parts of the image are saturated. Finally, sunrise fully saturates the camera image. This sequence is the closest thing to the astronaut's orbital viewpoint that LADEE could provide!
A good example of zodiacal light.
Image Credit:
Copyright: Yuri Beletsky (ESO)
The shape of this glow is familiar; we've seen it before. The images reveal a phenomenon that even we can see during a dark, clear night after sunset here on Earth – the zodiacal light. What is zodiacal light? It is the scattered sunlight from billions upon billions of dust grains, not at the Moon, but in the innermost reaches of the solar system. The origin of this dust appears to be comets, which shed gas and dust in their orbital progress around the sun. The lenticular shape of the zodiacal light, seen in the LADEE star tracker images, results from the tendency of the dust to be more concentrated near the orbital plane of the planets.
Unlike Eugene Cernan's sketches from his vantage point in the Apollo 17 command module, America, LADEE saw no rays or other strange features - just good old zodiacal light, plus possibly the outer fringes of the sun's corona. LADEE took several sequences of these orbital sunrise images, and for now, nothing has shown up that clearly is lunar in origin. In the coming weeks and months, we'll carefully analyze these images, and perhaps something related to levitated lunar dust will emerge.
But it sure looks like sunrise is just as impressive from LADEE's vantage point as it is to us on Earth.
LADEE Project Scientist Update: The Legacy Lives On!
The LADEE spacecraft has impacted the Moon, capping an extremely successful operational mission. Science analysis will continue for months, as the ...
NASA Completes LADEE Mission with Planned Impact on Moon's Surface
Ground controllers at NASA's Ames Research Center in Moffett Field, Calif., have confirmed that NASA's Lunar Atmosphere and Dust Environment Explorer ...
Ground controllers at NASA's Ames Research Center in Moffett Field, Calif., have confirmed that NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft impacted the surface of the moon, as planned, between 9:30 and 10:22 p.m. PDT Thursday, April 17.
LADEE lacked fuel to maintain a long-term lunar orbit or continue science operations and was intentionally sent into the lunar surface. The spacecraft's orbit naturally decayed following the mission's final low-altitude science phase.
During impact, engineers believe the LADEE spacecraft, the size of a vending machine, broke apart, with most of the spacecraft’s material heating up several hundred degrees – or even vaporizing – at the surface. Any material that remained is likely buried in shallow craters.
"At the time of impact, LADEE was traveling at a speed of 3,600 miles per hour – about three times the speed of a high-powered rifle bullet," said Rick Elphic, LADEE project scientist at Ames. "There’s nothing gentle about impact at these speeds – it’s just a question of whether LADEE made a localized craterlet on a hillside or scattered debris across a flat area. It will be interesting to see what kind of feature LADEE has created."
NASA completes the LADEE mission.
Image Credit:
NASA Ames
In early April, the spacecraft was commanded to carry out maneuvers that would lower its closest approach to the lunar surface. The new orbit brought LADEE to altitudes below one mile (two kilometers) above the lunar surface. This is lower than most commercial airliners fly above Earth, enabling scientists to gather unprecedented science measurements.
On April 11, LADEE performed a final maneuver to ensure a trajectory that caused the spacecraft to impact the far side of the moon, which is not in view of Earth or near any previous lunar mission landings. LADEE also survived the total lunar eclipse on April 14 to 15. This demonstrated the spacecraft's ability to endure low temperatures and a drain on batteries as it, and the moon, passed through Earth's deep shadow.
In the coming months, mission controllers will determine the exact time and location of LADEE's impact and work with the agency’s Lunar Reconnaissance Orbiter (LRO) team to possibly capture an image of the impact site. Launched in June 2009, LRO provides data and detailed images of the lunar surface.
"It's bittersweet knowing we have received the final transmission from the LADEE spacecraft after spending years building it in-house at Ames, and then being in constant contact as it circled the moon for the last several months," said Butler Hine, LADEE project manager at Ames.
Launched in September 2013 from NASA's Wallops Flight Facility in Virginia, LADEE began orbiting the moon Oct. 6 and gathering science data Nov. 10. The spacecraft entered its science orbit around the moon's equator on Nov. 20, and in March 2014, LADEE extended its mission operations following a highly successful 100-day primary science phase.
LADEE also hosted NASA’s first dedicated system for two-way communication using laser instead of radio waves. The Lunar Laser Communication Demonstration (LLCD) made history using a pulsed laser beam to transmit data over the 239,000 miles from the moon to the Earth at a record-breaking download rate of 622 megabits-per-second (Mbps). In addition, an error-free data upload rate of 20 Mbps was transmitted from the primary ground station in New Mexico to the Laser Communications Space Terminal aboard LADEE.
LADEE gathered detailed information about the structure and composition of the thin lunar atmosphere. In addition, scientists hope to use the data to address a long-standing question: Was lunar dust, electrically charged by sunlight, responsible for the pre-sunrise glow seen above the lunar horizon during several Apollo missions?
"LADEE was a mission of firsts, achieving yet another first by successfully flying more than 100 orbits at extremely low altitudes," said Joan Salute, LADEE program executive, at NASA Headquarters in Washington. "Although a risky decision, we're already seeing evidence that the risk was worth taking.”
A thorough understanding of the characteristics of our nearest celestial neighbor will help researchers understand other bodies in the solar system, such as large asteroids, Mercury and the moons of outer planets.
NASA also included the public in the final chapter of the LADEE story. A “Take the Plunge” contest provided an opportunity for the public to guess the date and time of the spacecraft’s impact via the internet. Thousands submitted predictions. NASA will provide winners a digital congratulatory certificate.
NASA's Science Mission Directorate in Washington funds the LADEE mission. Ames was responsible for spacecraft design, development, testing and mission operations, in addition to managing the overall mission. NASA's Goddard Space Flight Center in Greenbelt, Md., managed the science instruments, technology demonstration payload and science operations center, and provided mission support. Goddard also manages the LRO mission. Wallops was responsible for launch vehicle integration, launch services and operations. NASA's Marshall Space Flight Center in Huntsville, Ala., managed LADEE within the Lunar Quest Program Office.
For more information about the LADEE mission, visit: http://www.nasa.gov/ladee
For more information about LLCD, visit: http://llcd.gsfc.nasa.gov
Text issued as Ames news release 14-031AR
Dewayne Washington
Goddard Space Flight Center, Greenbelt, Md.
301-286-0040
dewayne.a.washington@nasa.gov
Goddard Space Flight Center, Greenbelt, Md.
301-286-0040
dewayne.a.washington@nasa.gov
LADEE Project Scientist Update: Citius, propius, occupatus
NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) performed its final orbital maintenance maneuver (OMM-22) last Friday evening, April 11. This was the 22nd maneuver during the science mission, designed to keep the spacecraft at the desired altitudes for the three science instruments to obtain their best data. After the primary mission concluded in March, we have been allowing the spacecraft to go much lower in altitude, in order to obtain the really high-value science data, accepting the risk of flying barely above the lunar terrain. We flew very close – approximately two miles (3.2 kilometers) above the surface – on April 5, and made it through just fine.
After safely flying through our close approach on April 5, we barely had time to breathe a sigh of relief when we had to face a most nerve-wracking moment on April 14: the day of a unusually long lunar eclipse, which the spacecraft was not designed to survive. The launch date in September 2013, and the primary science mission were chosen so that we could complete everything prior to this long eclipse. However, with our extended mission, not only are we able to gather valuable extra science data, but also conduct an engineering test by flying LADEE through the eclipse.
The total lunar eclipse, showing a coppery moon, the bright star Spica, and the planet Mars.
Image Credit:
NASA Ames/Lynn Hoffland
An eclipse like the one April 14-15, is challenging because there is no sunlight to power the spacecraft and heaters, or recharge the battery. The low temperatures mean the spacecraft needs power to keep itself from freezing. LADEE normally experiences a period of eclipse-like darkness that lasts about an hour every time it orbits the moon, but this extended eclipse lasted four hours. We watched telemetry as the spacecraft lost sunlight and then began to cool down. The battery discharged as the heaters kicked in, and we started receiving yellow and red alarms from the spacecraft as the power dropped and everything got colder. Once the eclipse ended, and the spacecraft started charging up again, the alarms gradually cleared and everything returned to normal. Aside from a couple of sensors getting too cold, everything looked good and we were once again able to gather science data. LADEE had survived the eclipse!
The OMM-22 maneuver was designed to get LADEE as low as we could for science measurements, but also placed the spacecraft on a trajectory that will naturally decay to the planned impact on the moon's far side on April 21. Now LADEE is in the final low-altitude passes prior to its planned impact. These altitudes are very low to the surface and so close to the walls of lunar craters and mountain ridges that there is a good chance the spacecraft may impact a few days ahead of that on April 17 or 18. This risk is definitely worth it, however, as it gives us the chance to collect really valuable science data at low altitudes that normally are impossible to safely achieve. If LADEE gets through these low altitudes by the evening of April 18, then the spacecraft will stay on its final path to for a planned impact in the night on Sunday, April 20 or early morning on Monday, April 21.
Not exactly the Olympic motto, but appropriate! On March 1, 2014, NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) successfully completed its full 100-day science mission. But LADEE has not been resting on its laurels! LADEE’s flight has been faster, lower and busier than ever. The science instruments have continued to acquire data for another bonus lunation – or a complete lunar day that lasts 29.5 Earth days – during the mission extension. It turns out that this extra time is important to understanding the sources and drivers of the tenuous lunar atmosphere, because conditions are never exactly the same from month to month. Plus, the more we learn about the moon, its dust and exosphere, the more skilled we become in planning precise instrument measurements at just the right times. We've also increased the duty cycle of our instrument operations and are burning more science hours per orbit than ever before.
This series of images portrays the moon’s surface illuminated by a nearly full Earth.
Image Credit:
NASA/Ames
LADEE’s star trackers have taken more cool images. This recent series portrays the Moon’s surface illuminated by a nearly full Earth. The images, taken once a minute, show the changes in lighting and terrain as LADEE approaches the boundary of the nearside and far side, where light from the bright Earth does not reach. The transition from smooth mare plains to the rugged, heavily cratered highlands is clear. In this series, Earth’s illumination angle changes from high to very low – the last image shows a few lonely mountain tops illuminated by the rays of the distant Earth, off to the left. You may notice that the stars above the limb never move – LADEE was in a fixed inertial attitude at the time, downloading science data to a ground station.
Taking images is an unusual task for a star tracker, since its main purpose is to determine where in space it is looking, like a navigator, so the spacecraft can know its attitude relative to sun, moon and Earth. It so happens that the star trackers are able to compress and save images every eight seconds. If those images contain not just stars, but the dark limb of the unlit moon, an interesting possibility presents itself: what if we could reproduce the famous view that Apollo astronaut Eugene Cernan sketched more than 40 years ago? What if we could see a horizon glow just before orbital sunrise? Might we see levitated dust, illuminated by sunshine while LADEE is in the dark shadow of the moon? More on this soon!
This is a sketch of the lunar sunrise seen from orbit by Apollo 17 astronaut Eugene Cernan. Highlights in the right image show the sources of the scattered light.
Image Credit:
NASA
LADEE has been flying lower than ever before, exploring new regions near the bottom of the moon's tenuous atmosphere and thin dust veil. In recent days we have flown as low as three kilometers (two miles) above the lunar terrain. Imagine the view from the Appennine Mountains at the eastern edge of Mare Imbrium, as LADEE races by at 1,650 meters per second (3,690 miles per hour, more than three times the speed of a high-powered rifle bullet) and 3,100 meters (10,000 feet) overhead.
Now LADEE's orbit is naturally evolving toward higher altitudes, but only temporarily – the end is near! LADEE will perform its 22nd and final orbit maintenance maneuver in the evening of Friday, April 11. This maneuver will lower periapsis – or the spacecraft's closest approach to the moon’s surface – to a few kilometers again, providing a second opportunity to acquire high-value science at low altitudes over a different part of the moon.
To make things even more interesting, there is a total lunar eclipse, a beautiful event visible from the United States, the night of April 14 to 15. But in lunar orbit NASA's LADEE, Lunar Reconnaissance Orbiter and the two Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) spacecraft must survive harsh conditions as they and the moon pass through Earth's deep shadow. Starved of sunlight for power and enduring deep cold, they will rely on batteries to see them through. Like the other missions, LADEE is expected to survive – but it wasn't designed to, and this is space, so surprises can occur. Keep little LADEE in your prayers as you gaze up at the beautiful eclipsing moon late Monday night!
It's not often that we get a chance to see our planet's shadow, but a lunar eclipse gives us a fleeting glimpse. During these rare events, the full Moon rapidly darkens and then glows red. Though a lunar eclipse can be seen only at night, it's worth staying up to catch the show.
Image Credit:
NASA's Goddard Space Flight Center
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