Moon Archives

March 7, 2014April 26, 2016 by Ken Kremer

NASA Lunar Orbiter snaps Spectacular Images of Yutu Moon Rover driving around Chang’e-3 Lander

Yutu rover drives around Chang’e-3 lander – from Above And Below
Composite view shows China’s Yutu rover and tracks driving in clockwise direction around Chang’e-3 lander from Above And Below (orbit and surface). The Chang’e-3 timelapse lander color panorama (bottom) and orbital view (top) from NASA’s LRO orbiter shows Yutu rover after it drove down the ramp to the moon’s surface and began driving around the landers right side, passing by craters and heading south on Lunar Day 1. It then moved northwest during Lunar Day 2. Arrows show Yutu’s positions over time.
Credit: CNSA/NASA/Ken Kremer/Marco Di Lorenzo/Mark Robinson
See below more mosaics and LRO imagery
Story updated[/caption]

The powerful telescopic camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO) has captured spectacular new images detailing the traverse of China’s Yutu moon rover around the landing site during its first two months exploring the Moon’s pockmarked grey terrain.

The newly released high resolution LRO images even show Yutu’s tracks cutting into the lunar surface as the world famous Chinese robot drove in a clockwise direction around the Chang’e-3 lander that delivered it to the ground in mid-December 2013.

You can precisely follow Yutu’s movements over time – from ‘above and below’ – in our new composite view (shown above) combining the latest LRO image with our timelapse mosaic showing the rover’s history making path from the touchdown point last December to today’s location.

Yutu is China’s first ever Moon rover and successfully accomplished a soft landing on the Moon on Dec. 14, 2013, piggybacked atop the Chang’e-3 mothership lander.

Barely seven hours after touchdown, the six wheeled moon buggy drove down a pair of ramps onto the desolate gray plains of the lunar surface at Mare Imbrium (Sea of Rains) covered by volcanic material.

LROC February 2014 image of Chang'e 3 site. Blue arrow indicates Chang'e 3 lander; yellow arrow points to Yutu (rover); and white arrow marks the December location of Yutu. Yutu's tracks can be followed clockwise around the lander to its current location. Image width 200 meters (about 656 feet). Credit: NASA/Goddard/Arizona State University — LROC February 2014 image of Chang’e 3 site. Blue arrow indicates Chang’e 3 lander; yellow arrow points to Yutu (rover); and white arrow marks the December location of Yutu. Yutu’s tracks can be followed clockwise around the lander to its current location. Image width 200 meters (about 656 feet). Credit: NASA/Goddard/Arizona State University

Altogether three images of the rover and lander have been taken to date by the Lunar Reconnaissance Orbiter Camera (LROC) aboard LRO – specifically the hi res narrow angle camera (NAC).

The LROC NAC images were captured on Dec. 25, 2013, Jan. 21, 2014 and Feb. 17, 2014 as LRO soared overhead.

The four image LRO composite below includes a pre-landing image taken on June 30, 2013.

Four LROC NAC views of the Chang'e 3 landing site. A) before landing, June 30, 2013 B) after landing, Dec. 25, 2013 C) Jan. 21, 2014 D) Feb. 17, 2014 Width of each image is 200 meters (about 656 feet). Follow Yutu's path clockwise around the lander in "D." Credit: NASA/Goddard/Arizona State University — Four LROC NAC views of the Chang’e 3 landing site. A) before landing, June 30, 2013 B) after landing, Dec. 25, 2013 C) Jan. 21, 2014 D) Feb. 17, 2014 Width of each image is 200 meters (about 656 feet). Follow Yutu’s path clockwise around the lander in “D.” Credit: NASA/Goddard/Arizona State University

Since the solar incidence angles were different, the local topography and reflectance changes between images showing different levels of details.

“In the case of the Chang’e 3 site, with the sun higher in the sky one can now see the rover Yutu’s tracks (in the February image),” wrote Mark Robinson, Principal Investigator for the LROC camera in an LRO update.

The solar powered rover and lander can only operate during periods of lunar daylight, which last 14 days each.

During each lunar night, they both must power down and enter hibernate mode since there is no sunlight available to generate power and no communications are possible with Earth.

Here is a gif animation from the NASA LRO team combining all four LROC images.

Four views of the Chang'e 3 landing site from before the landing until Feb. 2014. Credit: NASA/GSFC/Arizona State University — Four views of the Chang’e 3 landing site from before the landing until Feb. 2014. Credit: NASA/GSFC/Arizona State University

During Lunar Day 1, Yutu drove down the landers ramps and moved around the right side in a clockwise direction.

By the end of the first lunar day, Yutu had driven to a position about 30 meters (100 feet) south of the Chang’e-3 lander, based on the imagery.

See our complete 360 degree timelapse color panorama from Lunar Day 1 herein and at NASA APOD on Feb. 3, 2014 – assembled by Marco Di Lorenzo and Ken Kremer.

360-degree time-lapse color panorama from China’s Chang’e-3 lander. This new 360-degree time-lapse color panorama from China’s Chang’e-3 lander shows the Yutu rover at five different positions, including passing by crater and heading south and away from the Chang’e-3 lunar landing site forever during its trek over the Moon’s surface at its landing site from Dec. 15-22, 2013 during the 1st Lunar Day. Credit: CNSA/Chinanews/Ken Kremer/Marco Di Lorenzo – kenkremer.com. See our Yutu timelapse pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.htm

After awakening for Lunar Day 2, Yutu then moved northwest and parked about 17 meters (56 feet) southwest of the lander, according to Robinson.

By comparing the Janaury and February images “it is apparent that Yutu did not move appreciably from the January location,” said Robinson.

At this moment Yutu and the companion Chang’e-3 lander are sleeping through their 3rd Lunar Night.

They entered hibernation mode on Feb. 22 and Feb. 23, 2014 respectively.

Hopefully both probes will awaken from their slumber sometime in the next week when the Moon again basks in daylight glow to begin a 4th day of lunar surface science operations.

“We all wish it would be able to wake up again,” said Ye Peijian, chief scientist of the Chang’e-3 program, according to CCTV, China’s state run broadcaster.

However, the hugely popular ‘Yutu’ rover is still suffering from an inability to maneuver its life giving solar panels. It is also unable to move – as I reported here.

The 140 kg rover is now nearing its planned 3 month long life expectancy on a moon roving expedition to investigate the moon’s surface composition and natural resources.

China is only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.

Stay tuned here for Ken’s continuing Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, LADEE, Mars and more planetary and human spaceflight news. Learn more at Ken’s upcoming presentations at the NEAF astro/space convention on April 12/13.

Ken Kremer

Chang’e-3 lander and Yutu rover – from Above And Below Composite view shows China’s Chang’e-3 lander and Yutu rover from Above And Below (orbit and surface) – lander color panorama (top) and orbital view from NASA’s LRO orbiter (bottom). Chang’e-3 lander color panorama shows Yutu rover after it drove down the ramp to the moon’s surface and began driving around the landers right side to the south. Yellow lines connect craters seen in the lander panorama and the LROC image from LRO (taken at a later date after the rover had moved), red lines indicate approximate field of view of the lander panorama. Credit: CNSA/NASA/Ken Kremer/Marco Di Lorenzo/Mark Robinson

LRO slewed 54 degrees to the east on Feb. 16, 2014, to allow the LROC instrument to snap a dramatic oblique view of the Chang'e 3 site (arrow). Crater in front of lander is 450 meters (about 1,476 feet) in diameter. Image width is 2,900 meters (about 9,500 feet) at the center. Credit: NASA/Goddard/Arizona State University — LRO slewed 54 degrees to the east on Feb. 16, 2014, to allow the LROC instrument to snap a dramatic oblique view of the Chang’e 3 site (arrow). Crater in front of lander is 450 meters (about 1,476 feet) in diameter. Image width is 2,900 meters (about 9,500 feet) at the center. Credit: NASA/Goddard/Arizona State University

March 6, 2014December 23, 2015 by Jason Major

If the Moon Were Only One Pixel: a Scale Model of the Solar System

Josh Worth's HTML scale model of the Solar System

One of my favorite pet peeves is the inability of conventional models to accurately convey the gigantic scale of the Solar System. Most of us grew up with models of the planets made of wood or plastic or spray painted styrofoam balls impaled on bent wire hangers (don’t tell Mommy), or, more commonly, illustrations on posters and in textbooks. While these can be fun to look at and even show the correct relative sizes of the planets (although usually not as compared to the Sun) there’s one thing that they simply cannot relate to the viewer: space is really, really, really big.

Now there are some more human-scale models out there that do show how far the planets are from each other, but many of them require some walking, driving, or even flying to traverse their full distances. Alternatively, thanks to the magic of web pages which can be any size you like limited only by the imagination of the creator (and the patience of the viewer), accurate models can be easily presented showing the average (read: mind-blowingly enormous) distances between the planets… and no traveling or wire hangers required.

This is one of those models.* Enjoy.

Despite their similar apparent sizes in our sky, the Moon and Sun are (obviously) quite different in actual size. Which is a good thing for us. (Credit: Josh Worth)

Created by designer Josh Worth, “If the Moon Were Only 1 Pixel: A Tediously Accurate Scale Model of the Solar System” uses a horizontally-sliding HTML page to show how far it is from one planet to another, as well as their relative sizes, based on our Moon being just a single pixel in diameter (and everything lined up neatly in a row, which it never is.) You can use the scroll bar at the bottom of the page or arrow keys to travel the distances or, if you want to feel like you’re at least getting some exercise, scroll with your mouse or computer’s swipe pad (where applicable.) You can also use the astronomical symbols at the top of the page to “warp” to each planet.

Just try not to miss anything — it’s a surprisingly big place out there.

“You may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”

– Douglas Adams

See more of Josh Worth’s work here. (HT to Alan Stern.)

*And this is another one.

March 3, 2014April 26, 2016 by Ken Kremer

China’s Yutu Moon Rover Unable to Properly Maneuver Solar Panels

This time-lapse color panorama from China’s Chang’e-3 lander shows the Yutu rover at two different positions during its trek over the Moon’s surface at its landing site from Dec. 15-18, 2013. This view was taken from the 360-degree panorama.
Credit: CNSA/Chinanews/Ken Kremer/Marco Di Lorenzo.
See our complete 5 position Yutu timelapse pano herein and 3 position pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.htm
Story updated[/caption]

The serious technical malfunction afflicting the life and continued operations of China’s Yutu moon rover since the start of its second Lunar Night time hibernation in late January 2014 has been identified as an inability to properly maneuver the life giving solar panels, according to a top Chinese space official.

“Yutu suffered a control circuit malfunction in its driving unit,” according to a newly published report on March 1 by the state owned Xinhua news agency.

“The control circuit problem prevented Yutu from entering the second dormancy as planned,” said Ye Peijian, chief scientist of the Chang’e-3 program, in an exclusive interview with Xinhua.

At the time that Yutu’s 2nd Lunar sleep period began on Jan. 25, 2014, Chinese space officials had announced that the robot’s future was in jeopardy after it suffered an unidentified “ mechanical control anomaly” due to the “complicated lunar surface.”

A functioning control circuit is required to lower the rovers mast and protect the delicate components and instruments mounted on the mast from directly suffering from the extremely harsh cold of the Moon’s recurring night time periods.

“Normal dormancy needs Yutu to fold its mast and solar panels,” said Ye.

The high gain communications antenna and the imaging cameras are attached to the mast.

They must be folded down into a warmed electronics box to shield them from the damaging effects of the Moon’s nightfall when temperatures plunge dramatically to below minus 180 Celsius, or minus 292 degrees Fahrenheit.

The solar panels also generate power during each Lunar day to keep the robot alive and conduct its mission of scientific exploration roving across the lunar terrain.

The rover and Chang’e-3 stationary lander must power down and sleep during each lunar night since there is no sunlight available to generate power and no communications are possible with Earth.

The panel driving unit also helps maneuver the panels into position to efficiently point to the sun to maximize the electrical output.

“The driving unit malfunction prevented Yutu to do those actions” said Ye.

Each lunar day and night lasts for alternating periods of 14 Earth days.

“This means Yutu had to go through the lunar night in extremely low temperatures.”

Apparently the mast was not retracted and remained vertical during the lunar nights 2 and 3.

And the camera somehow survived the harsh temperature decline and managed to continue operating since it snapped two images of the Chan’ge-3 lander during Lunar Day 3. See our two image mosaic – below.

In addition to being chief scientist of the Chang’e-3 program Ye is also a member of the National Committee of the Chinese People’s Political Consultative Conference, the country’s top political advisory body.

Yutu is China’s first ever Moon rover and successfully accomplished a soft landing on the Moon on Dec. 14, 2013, piggybacked atop the Chang’e-3 mothership lander.

For a time in mid-February, mission scientists feared that Yutu would no longer function when because no signals were received until two days later than the planned “awakening” from Lunar Night 2 on Feb. 10.

Mosaic of the Chang'e-3 moon lander and the lunar surface taken by the camera on China’s Yutu moon rover from a position south of the lander. Note the landing ramp and rover tracks at left. Credit: CNSA/SASTIND/Xinhua/Marco Di Lorenzo/Ken Kremer — Mosaic of the Chang’e-3 moon lander and the lunar surface taken by the camera on China’s Yutu moon rover from a position south of the lander during Lunar Day 3. Note the landing ramp and rover tracks at left. Credit: CNSA/SASTIND/Xinhua/Marco Di Lorenzo/Ken Kremer

Fortunately, Yutu did finally wake up some 48 hours late on Feb. 12 and function on Lunar Day 3.

And the team engaged in troubleshooting to try and identify and rectify the technical problems.

Since then, Chinese space engineers engaged in troubleshooting to try and identify and rectify the technical problems in a race against time to find a solution before the start of Lunar Night 3.

The 140 kilogram rover was unable to move during Lunar Day 3 due to the mechanical glitches.

“Yutu only carried out fixed point observations during its third lunar day.” according to China’s State Administration of Science, Technology and Industry for National Defence (SASTIND), responsible for the mission.

However it did complete some limited scientific observations. And fortunately the ground penetrating radar, panoramic and infrared imaging equipment all functioned normally.

Yutu and the companion Chang’e-3 lander have again gone into sleep mode during Lunar Night 3 on Feb. 22 and Feb 23 respectively, local Beijing time.

But the issue with the control circuit malfunction in its driving unit remains unresolved and still threatens the outlook for Yutu’s future exploration.

See our new Chang’e-3/Yutu lunar panoramas by Ken Kremer and Marco Di Lorenzo herein and at NASA APOD on Feb. 3, 2014.

Yutu is now nearing its planned 3 month long life expectancy on a moon roving expedition to investigate the moon’s surface composition and natural resources.

The 1200 kg stationary lander is functioning normally. It is as expected to return science data about the Moon and conduct telescopic observations of the Earth and celestial objects for at least one year.

Yutu, which translates as ‘Jade Rabbit’ is named after the rabbit in Chinese mythology that lives on the Moon as a pet of the Moon goddess Chang’e.

“We all wish it would be able to wake up again,” said Ye according to CCTV, China’s state run broadcaster.

Ye will be reporting about Yutu and the Chang’e-3 mission at the annual session of the top advisory body, which opened today, Monday, March 3.

China is only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.

Stay tuned here for Ken’s continuing Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, Curiosity, GPM, LADEE, Mars and more planetary and human spaceflight news. Learn more at Ken’s upcoming presentations at the NEAF convention on April 12/13.

Ken Kremer

March 3, 2014December 23, 2015 by Nancy Atkinson

Astrophotos: Sun Halo, Crescent Moon and Earthshine

A solar halo was visible neara the Chilidog Observatory in Monterrey, Mexico. Credit and copyright: César Cantú.

Here’s a few great astrophotos for today! Astrophotographer César Cantú from the Chilidog Observatory in Monterrey, Mexico captured this stunning halo around the Sun on March 2, 2014. A solar halo is an optical phenomenon produced by ice crystals creating colored or white arcs and spots in the sky. Conditions in the atmosphere have to be just right, with moisture or ice crystals creating a “rainbow” effect around the Sun. Sometimes the halos surround the Sun completely, other times, they appear as arcs around the Sun creating what is known as sundogs. Basically, sunlight is reflecting off moisture in the atmosphere.

Ice crystals in Earth’s atmosphere can also cause rings around the Moon, and moondogs and even Venus “pillars.”

But make sure you look at the crescent Moon tonight — if you’ve missed seeing the thin crescent the past two evenings, tonight it will still be only 11% illuminated (according to Universe Today’s Phases of the Moon app!). Tonight you still might have the chance to see a little Earthshine — reflected Earthlight visible on the Moon’s night side.

See some great crescent Moon and Earthshine images below!

This image comes from one of our “regulars,” John Chumack, who says, “If you have clear skies, go out again tonight (03-03-2014) and look West between 7:00pm and 8:00pm EST, you will see the crescent Moon with Earthshine!”

Also, just another note from John: between 7:00 pm and 8:00 pm the Planet Uranus is 7.5 degrees below the Crescent Moon just after Sunset, but you will not see Uranus until it gets dark enough. You will need a telescope or binoculars to easily view Uranus at Magnitude 5.9, shortly after 8:15pm Uranus will set in the west and then the Moon follows shortly after that.

The young thin Crescent Moon with Earthshine was hanging low in the west near Tampa, Florida on March 2, 2014. Credit and copyright: John Chumack.

The Crescent Moon at 2.45 days old on March 3, 2014. Credit and copyright: James Lennie.

Crescent Moon with Earthshine on March 3, 2014. Credit and copyright: Raymond Gilchrist.

Check out more great images on our Flickr group page.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

February 28, 2014December 29, 2015 by Fraser Cain

Weekly Space Hangout – February 28, 2014: Good NASA News and 715 Confirmed Planets!

Host: Fraser Cain
Astrojournalists: Morgan Rehnberg, David Dickinson, Elizabeth Howell, Jason Major, Casey Dreier, Mike Simmons
Continue reading “Weekly Space Hangout – February 28, 2014: Good NASA News and 715 Confirmed Planets!”

February 26, 2014December 30, 2015 by Jason Major

Playing Marbles With The Planets

We’ve all seen charts showing the relative sizes of planets and moons compared to each other, which are cool to look at but don’t really give a sense of the comparative masses of the various worlds in our Solar System. It’s one thing to say the Earth is four times larger than the Moon, it’s entirely another to realize it’s 87 times more massive!

That’s where this new animation from astrophysicist Rhys Taylor comes in nicely.

Continue reading “Playing Marbles With The Planets”

February 24, 2014December 23, 2015 by Jason Major

Watch Saturn Slip Behind the Moon

Occultation of Saturn on Feb. 22, 2014 by Colin Legg

Or, more accurately, watch the Moon pass in front of Saturn. Either way you get the same result: a beautiful video of planetary motion in action!

On the morning of Saturday, Feb. 22, the Moon drifted in front of the planet Saturn from the point of view of certain locations on Earth. Luckily one of those locations was Perth, Australia, where astrophotographer Colin Legg happens to be, and thus we all get to enjoy the fantastic results of his photographic and astronomical acumen.

Check out the video below:

The occultation — as such events are called whenever one celestial object passes in front of, or “hides,” another (the root of the word means “to conceal”) — may make it look like a tiny Saturn is getting absorbed by a giant Moon. But (obviously) they are separated by a vast distance: at the time of the occultation, 9.658 AU, or about 1,444,816,000 kilometers (897.7 million miles).

These sort of events will become a bit more common as the Moon is “headed towards a ‘shallow’ year in 2015 relative to the ecliptic; it will then begin to slowly open back up and ride high around 2025,” according to a recent Universe Today article by David Dickinson.

For those of you interested, Colin lists his equipment as a Celestron C8, f/10, prime focus. His camera is a Canon 5D2, running Magic Lantern RAW video firmware in 3x crop mode @ 1880 x 1056 resolution. Footage was taken at 1/60 sec exposure, ISO 200, 10 fps.

See more of Colin’s work on his Facebook page here.

February 24, 2014December 23, 2015 by Nancy Atkinson

Watch a Car-Sized Asteroid Slam Into the Moon

An image of the flash resulting from the impact of a large meteorite on the lunar surface on 11 September 2013, obtained with the MIDAS observatory. Credit: J. Madiedo / MIDAS

Hey, all you astro-photographers/videographers out there: were you shooting the Moon back on September 11, 2013? You may want to review your footage and see if you captured a bright flash which occurred at about 20:07 GMT. Astronomers say a meteorite with the mass of a small car slammed into the Moon at that time and the impact produced a bright flash, and it even would have been easy to spot from the Earth.

According to astronomers Jose M. Madiedo, from the University of Huelva and Jose L. Ortiz, from the Institute of Astrophysics of Andalusia both in Spain, this impact was the longest and brightest confirmed lunar impact flash ever observed, as the “afterglow” of the impact remained visible for 8 seconds.

The astronomers think the bright flash was produced by an impactor of around 400 kg with a width of between 0.6 and 1.4 meters. The rock hit may have hit Mare Nubium at about 61,000 kilometers per hour (38,000 miles per hour) — although the uncertainty of the impact is fairly high, the team says in their paper. But if it is as high as they think, it may have created a new crater with a diameter of around 40 meters. The impact energy was equivalent to an explosion of roughly 15 tons of TNT.

This beats the previous largest impact seen – which occurred just six months earlier in March 2013 – which was estimated to pack as much punch as 5 tons of TNT. Astronomers that explosion was caused by a 40 kg meteoroid measuring 0.3 to 0.4 meters wide, traveling about 90,000 km/hr (56,000 mph.)

How often does an asteroid hit the Moon? Astronomers actually aren’t very sure.

On average, 33 metric tons (73,000 lbs) of meteoroids hit Earth every day, the vast majority of which harmlessly ablates or burns up high in Earth’s atmosphere, never making it to the ground. The Moon, however, has little or no atmosphere, so meteoroids have nothing to stop them from striking the surface.

The lunar impact rate is so uncertain because observations for objects in the mass range of visible impacts from Earth are quite few. But now, astronomers have set up networks of telescopes that can detect them automatically. NASA has the Automated Lunar and Meteor Observatory (ALaMO) at Marshall Space Flight Center, and the Spanish telescopes are part of the Moon Impacts Detection and Analysis System (MIDAS) system.

Lunar meteors hit the ground with so much kinetic energy that they don’t require an oxygen atmosphere to create a visible explosion. The flash of light comes not from combustion but rather from the thermal glow of molten rock and hot vapors at the impact site.

This thermal glow can be detected from Earth as short-duration flashes through telescopes. Generally, these flashes last just a fraction of a second. But the flash detected on September 11, 2013 was much more intense and longer than anything observed before.

Mosaic of zoomed images showing the flash evolution from the Sept. 11, 2013 impact during the first 2 seconds. Time increases from left to right in each row, starting from the upper left. The time interval between two consecutive images in the same row is 0.1 s. Credit: Madiedo, Ortiz, et al. 2014.

“Our telescopes will continue observing the Moon as our meteor cameras monitor the Earth’s atmosphere,” said Madiedo and Ortiz in a press release. “In this way we expect to identify clusters of rocks that could give rise to common impact events on both planetary bodies. We also want to find out where the impacting bodies come from.”

You can read the team’s paper here.

February 24, 2014March 8, 2017 by Fraser Cain

Can Moons Have Moons?

The Earth has a single moon, while Saturn has more than 60, with new moons being discovered all the time. But here’s a question, can a moon have a moon? Can that moon’s moon have its own moon? Can it be moons all the way down?

First, consider that we have a completely subjective idea of what a moon is. The Moon orbits the Earth, and the Earth orbits the Sun, and the Sun orbits the center of the Milky Way, which orbits within the Local Group, which is a part of the Virgo Supercluster. The motions of objects in the cosmos act like a set of Russian nesting dolls, with things orbiting things, which orbit other things. So maybe a better question is: could any of the moons in the Solar System have moons of their own? Well actually, one does.

Right now, NASA’s Lunar Reconnaissance Orbiter is happily orbiting around the Moon, photographing the place in high resolution. But humans sent it to the Moon, and just like all the artificial satellites sent there in the past, it’s doomed. No satellite we’ve sent to the Moon has ever orbited for longer than a few years before crashing down into the lunar surface. In theory, you could probably get a satellite to last a few hundred years around the Moon.

But why? How come we can’t make moons for our moon to have a moon of it’s own for all time? It all comes down to gravity and tidal forces. Every object in the Universe is surrounded by an invisible sphere of gravity. Anything within this volume, which astronomers call the “Hill Sphere”, will tend to orbit the object.

So, if you had the Moon out in the middle of space, without any interactions, it could easily have multiple moons orbiting around it. But you get problems when you have these overlapping spheres of influence. The strength of gravity from the Earth tangles with the force of gravity from the Moon.

How many moons are there in the Solar System? Image credit: NASA

Although a spacecraft can orbit the Moon for a while, it’s just not stable. The tidal forces will cause the spacecraft’s orbit to decay until it crashes. But further out in the Solar System, there are tiny asteroids with even tinier moons. This is possible because they’re so far away from the Sun. Bring these asteroids closer to the Sun, and someone’s losing a moon.

The object with the largest Hill Sphere in the Solar System is Neptune. Because it’s so far away from the Sun, and it’s so massive, it can truly influence its environment. You could imagine a massive moon distantly orbiting Neptune, and around that moon, there could be a moon of its own. But this doesn’t appear to be the case.

NASA is considering a mission to capture an asteroid and put it into orbit around the Moon. This would be safer than having it orbit the Earth, but still keep it close enough to extract resources. But without any kind of orbital boost, those tidal forces will eventually crash it onto the Moon. So no, in our Solar System, we don’t know of any moons with moons of their own. In fact, we don’t even have a name for them. What would you suggest?

February 23, 2014December 23, 2015 by Ken Kremer

Yutu Moon Rover Starts 3rd Night Time Hibernation But Technical Problems Persist

Chang’e-3/Yutu Timelapse Color Panorama
This newly expanded timelapse composite view shows China’s Yutu moon rover at two positions passing by crater and heading south and away from the Chang’e-3 landing site forever about a week after the Dec. 14, 2013 touchdown at Mare Imbrium. This cropped view was taken from the 360-degree timelapse panorama. See complete 360 degree landing site timelapse panorama herein and APOD Feb. 3, 2014. . Chang’e-3 landers extreme ultraviolet (EUV) camera is at right, antenna at left. Credit: CNSA/Chinanews/Ken Kremer/Marco Di Lorenzo – kenkremer.com.
See our complete Yutu timelapse pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.htm
Story updated[/caption]

The world famous and hugely popular ‘Yutu’ rover entered its 3rd Lunar night time hibernation period this weekend as planned, but serious technical troubles persist that are hampering science operations Chinese space managers confirmed.

“China’s lunar rover Yutu entered its third planned dormancy on Saturday, with the mechanical control issues that might cripple the vehicle still unresolved,” reports Xinhua, China’s official government news agency, in a mission status update newly released today (Feb. 23).

Yutu went to sleep on Saturday afternoon, Feb. 22, local Beijing time, according to China’s State Administration of Science, Technology and Industry for National Defence (SASTIND), responsible for the mission.

The companion Chang’e-3 lunar lander entered hibernation soon thereafter early today, Sunday, Feb 23.

See our new lunar panoramas by Ken Kremer and Marco Di Lorenzo herein and at NASA APOD on Feb. 3, 2014.

Yutu first encountered a serious technical malfunction a month ago on Jan. 25, when she suffered ‘a mechanical control anomoly’ just prior to entering hibernation for the duration of Lunar Night 2.

The abnormality occurred due to the “complicated lunar surface,” according to SASTIND.

Chinese space officials have not divulged the exact nature of the problems. And they have not released any details of the efforts to resolve the issues that “might cripple the vehicle.”

Since both Chinese Moon probes are solar powered, they must power down and enter a dormant mode during every two week long lunar night period when there is no sunlight to generate energy from their solar arrays. And no communications with Earth are possible.

The rover, nicknamed ‘Jade Rabbit’ remained stationary during the just concluded two week long lunar day time period, said SASTIND. It was unable to move due to the mechanical glitches.

“Yutu only carried out fixed point observations during its third lunar day.”

But it did complete some limited scientific observations. And fortunately the ground penetrating radar, panoramic and infrared imaging equipment are functioning normally.

The six wheel robot’s future was placed in jeopardy after it suffered the “mechanical anomaly” in late January 2014 and then awoke later than the scheduled time on Feb. 10, at the start of its 3rd Lunar Day.

To the teams enormous relief, a signal was finally detected.

“Yutu has come back to life!” said Pei Zhaoyu, the spokesperson for China’s lunar probe program, according to a Feb. 12 news report by the state owned Xinhua news agency.

“Experts are still working to verify the causes of its mechanical control abnormality.”

360-degree time-lapse color panorama from China’s Chang’e-3 lander This 360-degree time-lapse color panorama from China’s Chang’e-3 lander shows the Yutu rover at three different positions during its trek over the Moon’s surface at its landing site from Dec. 15-22, 2013 during the 1st Lunar Day. Credit: CNSA/Chinanews/Ken Kremer/Marco Di Lorenzo – kenkremer.com. See our Yutu timelapse pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.htm — 360-degree time-lapse color panorama from China’s Chang’e-3 lander
This 360-degree time-lapse color panorama from China’s Chang’e-3 lander shows the Yutu rover at three different positions during its trek over the Moon’s surface at its landing site from Dec. 15-22, 2013 during the 1st Lunar Day. Credit: CNSA/Chinanews/Ken Kremer/Marco Di Lorenzo – kenkremer.com. See our Yutu timelapse pano at NASA APOD Feb. 3, 2014: http://apod.nasa.gov/apod/ap140203.htm

Since then, Chinese space engineers sought to troubleshoot the technical problems and were in a race against time to find a solution before the start of Lunar Night 3 this weekend.

“Experts had feared that it might never function again, but Yutu “woke up” on Feb. 12, two days behind schedule,” reported Xinhua.

Each lunar day and night lasts for alternating periods of 14 Earth days.

During each long night, the Moon’s temperatures plunge dramatically to below minus 180 Celsius, or minus 292 degrees Fahrenheit.

Both solar powered probes must enter hibernation mode during each lunar night to conserve energy and protect their science instruments and control mechanisms, computers and electronics.

“Scientists are still trying to find a fix for the abnormalities,” said CCTV, China’s official state television network.

So Yutu is now sleeping with the problems unresolved and no one knows what the future holds.

Hopefully Jade Rabbit awakes again in about two weeks time to see the start of Lunar Day 4.

The Chang’e-3 mothership lander and piggybacked Yutu surface rover soft landed on the Moon on Dec. 14, 2013 at Mare Imbrium (Sea of Rains) – marking China’s first successful spacecraft landings on an extraterrestrial body in history.

‘Jade Rabbit’ had departed the landing site forever, and was journeying southwards as the anomoly occurred – about six weeks into its planned 3 month long moon roving expedition to investigate the moon’s surface composition and natural resources.

The 140 kg Yutu robot is located some 100 m south of the lander.

The 1200 kg stationary lander is expected to return science data about the Moon and conduct telescopic observations of the Earth and celestial objects for at least one year.

Chang’e-3 and Yutu landed on a thick deposit of volcanic material.

Landing site of Chinese lunar probe Chang'e-3 on Dec. 14, 2013. — Landing site of Chinese lunar probe Chang’e-3 on Dec. 14, 2013.

China is only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.

Stay tuned here for Ken’s continuing Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, LADEE, Mars and more planetary and human spaceflight news.

Ken Kremer