Planet Mercury as seen from the MESSENGER spacecraft in 2008. Credit: NASA/JPL
Virtually every planet in the Solar System has moons. Earth has The Moon, Mars has Phobos and Deimos, and Jupiter and Saturn have 67 and 62 officially named moons, respectively. Heck, even the recently-demoted dwarf planet Pluto has five confirmed moons – Charon, Nix, Hydra, Kerberos and Styx. And even asteroids like 243 Ida may have satellites orbiting them (in this case, Dactyl). But what about Mercury?
If moons are such a common feature in the Solar System, why is it that Mercury has none? Yes, if one were to ask how many satellites the planet closest to our Sun has, that would be the short answer. But answering it more thoroughly requires that we examine the process through which other planets acquired their moons, and seeing how these apply (or fail to apply) to Mercury.
Where did Mars’ moons Phobos and Deimos come from? How did they end up in orbit around Mars? This cool video from the folks at Kurzgesagt answers the most-oft asked questions about these mini moons.
You should also check out their other wonderful videos, like the one about our own Moon, below, which explains how big our Moon really is. The answer might surprise you.
Mars moon Phobos rising in the night time Martian sky shortly after sunset in this image from a movie taken by NASA's Mars rover Curiosity on Sol 317, June 28, 2013. The apparent ring is an imaging artifact The Credit: NASA/JPL-Caltech See the complete ‘Phobos Rising’ movie below
Mars moon Phobos (above, center) rising in the night time Martian sky shortly after sunset in this still image from a movie taken by NASA’s Mars rover Curiosity on Sol 317, June 28, 2013. The apparent ring is an imaging artifact. Credit: NASA/JPL-Caltech See the complete ‘Phobos Rising’ movie below [/caption]
Every once in a while when the time is just right and no one is looking, Curiosity’s Earthly handlers allow her some night time Martian delights.
In this case a pair of rising and setting celestial events bookend another magnificent week in humankinds exploration of the Red Planet – courtesy of NASA.
This past week NASA’s Curiosity rover captured esthetically stunning imagery of Phobos rising and Our Sun setting on Mars.
Phobos is the larger of Mars pair of tiny moons. The other being Diemos.
On June 28, (Sol 317) Curiosity aimed her navigation camera straight overhead to captured a breathtaking series of 86 images as Phobos was ascending in the alien evening sky shortly after sunset.
NASA combined these raw images taken over about 27 minutes into a short movie clip, sped up from real time.
Video Caption: ‘Phobos Rising’ – This movie clip shows Phobos, the larger of the two moons of Mars, passing overhead, as observed by NASA’s Mars rover Curiosity in a series of images centered straight overhead starting shortly after sunset. Phobos first appears near the lower center of the view and moves toward the top of the view. The images were taken on June 28, 2013. The apparent ring is an imaging artifact. Credit: NASA/JPL-Caltech
The pockmarked and potato shaped moon measures about 26.8 × 22.4 × 18.4 kilometers.
Phobos orbits barely some 6,000 km (3,700 mi) above the Martian surface. One day far in the future, it will crash and burn.
On June 22, Curiosity snapped an evocative series of Martian sunset photos as Sol set behind the eroded rim of Gale Crater – see below.
In the 2030’s, Humans may visit Phobos first before setting foot on the much more technically challenging Red Planet.
Sunset at Gale Crater
Martian sunset vista at Gale crater rim snapped by Curiosity on Sol 312, June 22, 2013. Colorized navcam image. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo
Phobos from NASA’s Mars Reconnaissance Orbiter on March 23, 2008. Credit: NASA
Artist concept of Russia’s Phobos-Grunt spacecraft. Credit Roscosmos.
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In less than 48 hours, Russia’s bold Phobos-Grunt mechanized probe will embark on a historic flight to haul humanities first ever soil samples back from the tiny Martian moon Phobos. Liftoff from the Baikonur Cosmodrome remains on target for November 9 (Nov 8 US 3:16 p.m. EDT).
For an exquisite view of every step of this first-of-its-kind robot retriever, watch this spectacular action packed animation (below) outlining the entire 3 year round trip voyage. The simulation was produced by Roscosmos, Russia’s Federal Space Agency and the famous IKI Space Research Institute. It’s set to cool music – so don’t’ worry, you don’t need to understand Russian.
The highly detailed animation begins with the blastoff of the Zenit booster rocket and swiftly progresses through Earth orbit departure, Phobos-Grunt Mars orbit insertion, deployment of the piggybacked Yinghuo-1 (YH-1) mini satellite from China, Phobos-Grunt scientific reconnaissance of Phobos and search for a safe landing site, radar guided propulsive landing, robotic arm manipulation and soil sample collection and analysis, sample transfer to the Earth return capsule and departure, plummeting through Earth’s atmosphere and Russian helicopter retrieval of the precious cargo carrier.
Video Caption: Every step of Russia’s Phobos-Grunt soil retrieval mission. Credit: Roscosmos/IKI
Video Caption: On October 21, the Phobos-Grunt spacecraft arrived at the Baikonur Cosmodrome and was uncrated and moved to assembly building 31 for fueling, final preflight processing and encapsulation in the nose cone. Credit: Roscosmos
Labeled Schematic of Phobos-Grunt and Yinghou-1 (YH-1) orbiter. Credit: Roskosmos
The Phobos-Grunt spacecraft is scheduled blastoff on November 9, 2011 from Baikonur Cosmodrome. It will reach Mars orbit in 2012 and eventually land on Phobos and return the first ever soil samples back to Earth in 2014. Credit Roscosmos
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Russia’s Space Agency, Roscosmos, has set November 9 as the launch date for the Phobos-Grunt mission to Mars and its tiny moon Phobos. Roscosmos has officially announced that the audacious mission to retrieve the first ever soil samples from the surface of Phobos will blastoff from the Baikonur Cosmodrome in Kazakhstan atop a Zenit-2SB rocket at 00:16 a.m. Moscow time.
Roscosmos said that engineers have finished loading all the propellants into the Phobos-Grunt main propulsion module (cruise stage), Phobos lander and Earth return module at Facility 31 at Baikonur.
Russian Phobos-Grunt spacecraft is set to launch to Mars on November 9, 2011.
L-shaped soil sample transfer tube extends from Earth return module ( top -yellow) and solar panel to bottom (left) of lander module. 2 landing legs, communications antenna, sampling arm, propulsion tanks and more are visible. Credit Roscosmos
Technicians also fueled the companion Yinghou-1 mini-satellite, provided by China, that will ride along inside a truss segment between the MDU propulsion module and the Phobos-Grunt lander.
The 12,000 kg Phobos-Grunt interplanetary spacecraft is being moved to an integration and test area at Facility 31 for integration with the departure segments of the Zenit rocket.
The next step is to enclose Phobos-Grunt inside the protective payload fairing and transport it to Facility 42 for mating atop the upper stage of the stacked Zenit-2SB booster rocket.
After about an 11 month journey, the spaceship will enter Mars orbit and spend several months searching for a suitable landing site on Phobos. The goal of the bold mission is to retrieve up to 200 grams of soil and rock from Phobos and return them to Earth in August 2014. The samples will help unlock the mysteries of the origin and evolution of Phobos, Mars and the Solar System.
Phobos-Grunt is equipped with a powerful 50 kg payload of some 20 international science instruments.
The 110 kg Yinghou-1, which translates as Firefly-1, is China’s first spaceship to voyage to Mars. It will be jettisoned by Phobos-Grunt into a separate orbit about Mars. The probe will photograph the Red planet with two cameras and study it with a magnetometer to explore Mars’ magnetic field and science instruments to explore its upper atmosphere.
Earth’s other mission to Mars in 2011, NASA’s Curiosity rover, is set to blast off for Mars on Nov. 25
Labeled Schematic of Phobos-Grunt and Yinghou-1 (YH-1) orbiter
<>. Mission Poster for the Russian Phobos-Grunt soil sample return spacecraft set to launch to Mars and its moon Phobos in November 2011. Phobos-Grunt consistes Credit: Roskosmos - Russian Federal Space Agency
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Russia is marking the upcoming blastoff of their dauntingly complex Phobos-Grunt sample return mission to the Martian moon Phobos with the release of a quite cool looking mission poster – see above. Phobos-Grunt translates as Phobos-Soil and is due to liftoff on or about November 7, 2011 from the Baikonur Cosmodrome atop a Zenit rocket.
The holy grail of Mars exploration has long been a sample return mission. But with severe cutbacks to NASA’s budget that goal is realistically more than a decade away. That’s why Phobos- Grunt is so exciting from a scientific standpoint.
Phobos-Grunt Orbiter/Lander
Russia's Phobos-Grunt is designed to land on Mars' moon Phobos, collect soil samples and return them to Earth for study. The lander will also carry scientific instrumetns to study Phobos and its environment. It will travel to Mars together with Yinghuo-1, China's first mission to the Red Planet. Credit: NPO Lavochkin
Phobos-Grunt Robotic sampling arm. Credit: Roskosmos
If successful, this audacious probe will retrieve about 200 grams of soil from the diminutive moon Phobos and accomplish the round trip in three years time by August 2014. Scientists speculate that martian dust may coat portions of Phobos and could possibly be mixed in with any returned samples.
Included here are more photos and graphics of the Phobos-Grunt spacecraft which is equipped with two robotic arms and a sampling device to transfer regolith and rocks to the Earth return vehicle and an on board array of some 15 science instruments, including lasers, spectrometers, cameras and a microscope. Readers please feel free to help with Russian translations.
Phobos-Grunt Model
This is a full-scale mockup of Russia's Phobos-Grunt. The spacecraft will collect samples of soil on Mar's moon Phobos and to bring the samples back to Earth for detailed study. Credit: CNES
Phobos-Grunt is the first of Earth’s two missions launching to the Red Planet in 2011. NASA’s Curiosity Mars Science Laboratory is due to lift off on Nov. 25, 2011 from Cape Canaveral, Florida.
ESA’s Mars Express orbiter took images last month of Mars two moons, Phobos and Deimos. This is the first time the moons have been imaged together in high resolution, but as Emily Lakdawalla points out on Planetary Blog, not the first time the two have been imaged together: the Spirit rover did it back in 2005! But these new image definitely provide a ‘wow’ factor, as well as helping to validate and refine existing orbit models of the two moons.
Phobos and Deimos together for the first time in high resolution. Credits: ESA/DLR/FU Berlin (G. Neukum)
“It doesn’t happen very often that both Martian moons are right in front of the camera, directly one behind the other,” said Harald Hoffmann from the German Aerospace Center (DLR).
“During the now more than six-year long project, we have had several opportunities to photograph the two moons together,” said Klaus-Dieter Matz, who worked with Hoffmann to plan the acquisition of these images. “The geometry of the constellation during Orbit 7492 on 5 November 2009 was especially favorable, so this time we wanted to try taking a sequence of photographs – and this first attempt has delivered the expected result!”
The geometrical relationships between Mars, its moons and the Mars Express probe at the time of the sequence. Credit: DLR
Phobos, the larger of the two moons, orbits closer to the Red Planet, circling it every 7 hours and 39 minutes. It travels faster relative to Mars than the Moon relative to Earth. It was 11,800 km from Mars Express when the images were taken. Deimos was 26,200 km away.
The images were acquired with the Super Resolution Channel (SRC) of the High Resolution Stereo Camera (HRSC). The camera took 130 images of the moons on 5 November at 9:14 CET over period of 1.5 minutes at intervals of 1s, speeding up to 0.5-s intervals toward the end. The image resolution is 110 m/pixel for Phobos and 240 m/pixel for Deimos — since Deimos was more than twice as far from the camera.
