Hours after its successful flyby of “the jewel of the solar system”, the robotic traveler Rosetta continues to return data from the encounter. From a point of light discovered in 1969 into a world of new vistas, here is Asteroid (2867) Steins:

Credits: ESA ©2008 MPS for OSIRIS Team MPS/UPM/LAM/IAA/RSSD/INTA/UPM/DASP/IDA - Cutout of “Asteroid Steins seen from a distance of 800 km“

At a press conference to announce preliminary results and to show the first images of Steins, European Space Agency (ESA) scientists compared the shape of the asteroid to that of a jewel and a diamond. The predicted shape model based on data obtained from Earth-based telescopes held up during the encounter, but the asteroid turned out to be nearly 10% bigger than expected. At its largest diameter Steins measures 5.9 kilometers, and at its smallest 4.0 kilometers.

Credits: ESA ©2008 MPS for OSIRIS Team MPS/UPM/LAM/IAA/RSSD/INTA/UPM/DASP/IDA - “Asteroid Steins seen from a distance of 800 km“.

Steins is marked by a large 2.0 kilometer crater on its top hemisphere and a chain of seven craters that stretch from the rim of this large crater down the side of the asteroid. Whether or not these are secondary craters (fall back of material from an initial and larger impact) or a distinct primary impact event is unclear. Scientists counted 23 craters and believe they are of a variety of ages, suggesting a complex impact history.

To date, spacecraft have now explored eight asteroids up close. Steins is different from the previously explored asteroids, however; it is an E-type body, a member of an asteroid family that is iron-poor and silicate rich compared to other families. Scientists will pour over the new data to determine the asteroid’s composition, mineralogy, topography, age, spin axis orientation, and impact history.

Credits: ESA ©2008 MPS for OSIRIS Team MPS/UPM/LAM/IAA/RSSD/INTA/UPM/DASP/IDA - “Anaglyph image of Steins“

Angioletta Coradini, Principal Investigator, announced that her team got a jump on calibration efforts using data from the VIRTIS (Visible and Infrared Mapping Spectrometer) instrument. She said that with quick input from the navigation team, a stable spacecraft platform, and extensive planning prior to the flyby, the team was able to provide nearly real-time calibration for the other instruments.

Gale Winters, ESA Director of Operations and Infrastrucuture, used the press conference to announce the Space Situational Awareness proposal. This proposed ESA and European program will conduct surveillance and tracking of a variety of objects in space, including Near-Earth asteroids that pose impact risk. The program will also support imaging of these objects and monitoring of space weather. Program researchers will use new data like those provided today from Rosetta to better understand these impact threats.

According to Andrea Accomazzo, Spacecraft operations Manager, the Steins flyby pushed Rosetta to the limits of its capabilities. The complex flyby required thermal protection of the spacecraft’s back end, where the Philae lander awaits its future encounter with Comet 67P/Churyumov-Gerasimenko. In addition, poorly constrained orbital information based on monitoring from Earth-based instruments required autonomous fine-tuning from Rosetta itself. Rosetta began tracking Steins on August 4, 2008 to better calculate its position and make the necessary course corrections to bring the spacecraft within 800 kilometers of the asteroid’s surface. The spacecraft came within two kilometers of this target distance.

Rosetta remains in good shape for the rest of its mission. The NAC (narrow-angle camera) went into safe mode just prior to the encounter due to conservative guidelines meant to protect the instrument for its primary mission at Comet 67P/Churyumov-Gerasimenko. The camera went back into operations not long after the encounter and successfully took more images as Steins receded.

Next up for Rosetta: a flyby of Earth in November 2009 and a flyby of Asteroid (21) Lutetia on June 10, 2010. Rosetta will arrive at its final destination Comet 67P/Churyumov-Gerasimenko in May 2014.

More Information

• Rosetta
  • Rosetta Blog
  • Press Release: “Steins: A diamond in the sky“

Related Books

[Commentary]

Credit: Screenshot of Amazon Video On Demand

Late last year Adobe released an upgrade to their ubiquitous Flash software that enabled higher quality video. In response, overall video streaming quality on the web has improved as various video services have upgraded their offerings. Amazon is the latest to make the leap, turning their unsuccessful and Windows-only Unbox digital media download service into a streaming digital media service. Amazon Video On Demand finally brings their large digital library of movies and television series to Apple Macs, removes the requirement for a separate software download, and offers compelling competition to Apple’s iTunes.

Downloads have not disappeared. Amazon Video On Demand offers both streaming in your browser and downloads to the Unbox software. However, the streaming service is meant to reduce or even eliminate the need for downloads. Digital media purchases remain in the Amazon cloud, available from anywhere you have access to the site and a sufficient internet connection.

I tested the new service with “Superman Returns”, a movie I purchased on Unbox over a year ago. The movie was only available for purchase for a short time. After I first downloaded the movie, I had subsequently removed all videos from my computer. When I tried to download “Superman Returns” later, I discovered that the draconian movie studio requirements prevented a second download. I was stuck with a purchase I could not watch.

Now that my video purchases are in the cloud, I was surprised and delighted to see I again have access to “Superman Returns.” Previous Unbox purchases show up in “Your Video Library” along with new purchases, ready and waiting to be streamed.

Credit: Screenshot of Amazon Video On Demand “Your Video Library”. Well, My Video Library.

Video starts playing immediately. Video quality depends on the speed of your internet connection and network congestion. Apparently there is no buffering, though this could potentially improve the video quality at the expense of immediate access. Over my 12 mbps cable modem connection from Cox Communications and then over wireless, video quality started out poor, but improved quickly as the connection and streaming seemed to “take.” A “Connection” status button on the video menu bar notes kbit/sec and the video quality, up to mbps speeds and 480p (DVD quality.) The quality can fluctuate, but after minor stuttering early in the movie, the streaming stabilized until I was lost in the movie. If this quality can be maintained during network congestion in my local area and as more people begin to use the service, then Amazon Video On Demand may very well be considered a success.

The video menu bar has your standard video controls including play, pause, skip back, skip forward, and volume control. Video can be popped out of the video library page or launched into full screen. A download button allows you to archive the purchase and play locally from your computer, but, again, I think streaming success may make this unnecessary. While the button is also available on a Mac, the download is sent to your registered PC (you control the destination in your Amazon account settings) and Unbox installation. Unbox software is still unavailable for Mac or Linux computers, and you cannot transfer video to iPods.

Credit: Screenshot of Amazon Video On Demand playing “Superman Returns”. Can you read my mind? Do you know what it is that you do to me, Brandon Routh? I mean, Superman?

Amazon Video On Demand is fast, easy, and a much better experience than using the clunky Unbox download and player software. I have long desired to make a complete switch from PC to Mac, but a few remaining services I could not get on a Mac have delayed the change; my Macbook Pro sits side-by-side with my desktop PC. With my videos in the cloud, that final switch is coming soon.

How does the experience stack up against iTunes? ITunes remains the high bar against which all other digital media services will be compared. I have slowly begun to purchase more music from Amazon because everything there is DRM-free, but doing so does require a download of Amazon software that sends your purchases to iTunes. When it comes to video, Amazon potentially has the upper-hand (I would like to play with the service longer before I come to any firm conclusions.) All you need is a browser and an Amazon account. Amazon’s ease of purchase and the instant play capabilities of Video On Demand mean you can get started watching video right away, with little to none of the delay required for Unbox or iTunes downloads. Hard drive space is no longer a barrier to owning as many movies and television shows as you want. I had better watch my wallet…

Unfortunately, NBC Universal and their popular television series may be the deciding factor for some people between Amazon Video On Demand and iTunes, though this might to some extent be offset by Disney/ABC television series available only on iTunes. There is NO question that I will be watching the final episodes of Battlestar Galactica using Amazon’s service. Frankly, I have never understood why NBC Universal decided to settle for no further iTunes sales even while developing Hulu.com and propping up the offerings on Amazon. I still hope they will return to iTunes but this is no longer required for me to continue purchasing and watching my favorite NBC series.

With a movie library much larger than iTunes, similar television offerings, NBC Universal TV series, availability through most any browser with Flash on most any computer, a smooth transition for your previous Unbox purchases, and a beta of a service that will stream video to Sony BRAVIA televisions, Amazon Video On Demand is pretty fantastic so far. High definition video on demand will make or break all competing digital media services, a battleground I suspect all players will enter in a big way in just a few months. Amazon Video On Demand could be particularly successful internationally where many countries have far superior internet speeds to what we suffer through here in the United States. Verizon FiOS Internet customers in the United States might also be big winners, the lucky jerks.

We might see as early as next Tuesday how Apple plans to respond. I predict that I will make use of both services for some time to come. For there to be a clear winner between Amazon, Apple, and the other competitors, they will have to add new features including extras and high definition as quickly as possible, while maintaining and improving the quality of both the video and the experience. So far, I like what I see with Amazon Video On Demand.

Credit: ESA TV - “Rosetta spacecraft meets asteroid Steins“

Rosetta, the European Space Agency (ESA) spacecraft on its way to orbit and deploy a lander on a comet, is now approaching Asteroid (2867) Steins. The flyby will bring the spacecraft within 800 km of Steins on Friday evening, September 5, 2008. The ESA will provide a webcast about the event beginning on September 06, 2008 from 04:00 until 11:20 GMT on the Rosetta website. Data is expect on Saturday after the flyby has been completed.

Steins is 4.6 km in diameter and located in the main asteroid belt. Rosetta will collect information about the asteroid as it speeds by on its way to Comet 67P/Churyumov-Gerasimenko.

Here is the Steins flyby timeline provided by ESA on the Rosetta Blog:

Timeline of nominal fly-by events

(All event times stated in ground time, CEST)

1 September

02:20 Instruments switched on (except OSIRIS which was already on for the navigation campaign)

4 September

07:20-11:20 Slot for possible trajectory correction manoeuvre (36 hours before closest approach)

13:20-18:20 Last opportunity to acquire images for optical navigation campaign

5 September

07:20-10:20 Slot for possible trajectory correction manoeuvre (12 hours before closest approach)

10:20 Navigation cameras switch to tracking mode - initially both used, then use CAM ‘A’ only (to be decided)

11:00 Uplink fly-by commands for asteroid fly-by mode (AFM)

Includes an update to the command profile already on board & the final updated AFM commands

20:18-20:38 Spacecraft ‘flip over’

20:39 Spacecraft switches automatically to asteroid fly-by mode

20:48 High-gain antenna on hold

From 10 minutes before to about 1 hour after closest approach, the high-gain antenna will not point to Earth. No telemetry will be received until the spacecraft exits the asteroid fly-by mode.

20:56 Sun illuminates Rosetta from the back and the asteroid fully

20:58 Closest approach, at a planned distance of 800 km from the asteroid

21:58 Rosetta automatically exits asteroid fly-by mode, high-gain antenna rotated to Earth pointing (until 22:05)

22:27 First post-fly-by acquisition of signal (AOS) - telemetry received via NASA’s Goldstone ground station

22:30 Start of science data download via Goldstone

6 September

04:06-16:01 Ground station pass via ESA’s New Norcia station - science data download continues. During the first 5 hrs, OSIRIS data will be downloaded, followed by 3:30 hrs of VIRTIS only, and then the rest of the science data

12:00 Live streaming of Rosetta Steins fly-by press conference from ESOC begins

13:00 Images from fly-by published on ESA web

15:00 End of press conference streaming

16:01 End of reception of first set of science data

After 6 September

Daily ground station passes until 5 October, including 8 hrs via New Norcia & one 4-hr DSN pass daily until 14 September - then daily passes via New Norcia only until 5 October.

As soon as the first closeup images of Steins are returned, I will update this page to change the background to a specific Steins theme. Please visit Frontier Channel on Saturday for the latest updates on the flyby.

More Information

• Rosetta
  • Press Release: “Rosetta spacecraft meets asteroid Steins“
  • Rosetta Blog
  • “Asteroid (2867) Steins: a portrait“

Related Books

Venus is the Earth-that-could-have-been and the Earth-that-still-might-be.  Our so called sister planet orbits second from the Sun. Cloudy, hot, and unhospitable to life as we know it, Venus demonstrates as well as Mars why comparative planetary science can greatly improve understanding of our own planet.

The greenhouse effect on Venus results in a poorly understood phenomena called zonal super-rotation. Hurricane winds across the cloud tops help the atmosphere to rotate much faster than the planet itself, but these winds give way to barely a breeze at the surface. The atmosphere is primarily carbon dioxide with some nitrogen. Thick sulfur dioxide clouds and other particulates conspire to hide the surface. The USSR visited the surface of Venus with several landers, some that included cameras, while orbiters with radar equipment accomplished global surface mapping last decade by orbiters. Mountains, volcanoes, pancake domes, plains, channels, and a impact craters have been discovered on the surface. The surface appears to be geologically young, despite little evidence for plate tectonics, the process on the Earth that recycles old crust and exudes new crust. The youthfulness of the Venusian surface may be due to catastrophic upheavals that periodically see the crust overturned (this might have last occurred from 300 to 500 million years ago).

Credit: JPL/NASA - “Volcano Sapas Mons“

The European Space Agency’s Venus Express is the latest mission to Venus and still ongoing. The orbiter has been tasked with several years of cloud and atmospheric studies and has already discovered a level of complexity in the clouds that had not been previously seen. “Boiling” clouds at low latitudes become streaky clouds at mid latitudes. At the poles thick and uniform clouds are interrupted rarely by darker streaks. At both poles there are huge vortexes in the cloud decks with mysterious features that resemble the eye of a hurricane that constantly changes shape.

Credit: ESA/MPS/DLR/IDA - “False-colour ultraviolet image of the Southern hemisphere of Venus“

Now in an extended mission, Venus Express in July 2008 began a series of maneuvers to bring it closer to Venus.

The history of Venus remains a mystery. Was it ever more like Earth, and if so, what happened? Why does the surface appear to be geologically young, and what is creating the sulfuric acid and other particulates in the atmosphere? Could life exist in more temperate zones in the clouds?

Answering these questions will in turn tell us more about the Earth. Venus, perhaps, provides a snapshot of our own future, if our greenhouse effect were to speed away out of our control. Knowing more about the end result could help us avoid the same fate.

More Information

• Venus Express
• Magellan
• Previous Coverage of Venus on Frontier Channel

Related Books

“Planetary Provenance” Posts

• Mercury
• Venus

[Commentary] | [Spoilers]

Credit: Hermit of the Mountain, LLC - Venus Rises promotional wallpaper: “Mars Warship Wallpaper“

A new surge in independently-produced online content is almost upon us even as existing media giants like NBC Universal begin to dabble in higher production value content intended for the web. Venus Rises, created by writer/director and Executive Producer J. G. Birdsall is especially noteworthy because this is not fan fiction. Based on an original idea, Venus Rises will be an ongoing series available online and on Illusion, a video-on-demand science fiction cable network. In development since the idea was conceived in 2002, a prequel to Venus Rises has finally been released, leading up to the series’ first episode.

The prequel is designed to introduce the universe in which this science fiction tale of two planets will play out. After the ecological collapse of the Earth, humanity fled to Mars and Venus, leading to class divisions across the vacuum. “Ikarus - Part 1″ explores the dynamics of a prospecting crew searching for resources in the Asteroid Belt.

Science fiction movies and television set in space have long been known for their scientific inaccuracies. Meanwhile, current scientific and technological progress underlines how reality can be stranger than fiction. Going into this prequel to a series I have been long anticipating, I admit that these two facts were foremost in my mind. How will independent science fiction producers deal with the same issues facing movie studies and television networks: cutting-edge movie-making technologies often paired with inane retreads of tired ideas?

The results are, in a word, mixed.

The opening credits really draw the viewer into the larger back story. Newspaper clippings and news reports hint at the seriousness of the disasters that befell Earth. As “Part 1″ gets started, the first CGI view of the mining hauler Ikarus is both tantalizing and a bit disappointing, especially after we enter the spacecraft. Inside the spacecraft, the set and onscreen graphics are top notch. Unfortunately, this makes the CGI outside the spacecraft stand out in contrast. For an independent production all the computer graphics, inside or out, are still noteworthy and show an attention to detail that is admirable.

Hard science fiction - that is, the kind of science fiction that gets into the nuts and bolts of science, discovery, and exploration - is underrepresented in movies and television. “Ikarus - Part 1″ is therefore refreshing in its attention to the spacecraft and other technical details. The remote sensing capabilities of the vessel are fun to watch. Asteroids, of course, are not really as close together as they are depicted here (and in most science fiction movies and TV, for that matter.)

Caption: Screenshot from “Ikarus - Part 1″. Asteroids are only this close together in science fiction movies and television.

What follows with the introduction of the crew is confusing, slightly melodramatic, and potentially cliched (depending on how this all turns out…this is “Part 1″ after all.) The men are dicks and Aeriana Onaar, a character played by Julia Hiroko Howe who will also be in the series, is at their apparent mercy. She is a “dumb mute” according to one of the evil crew members but can read lips and land drones with precision on the asteroid. What happens by the end of “Part 1″ has nothing to do with space and everything to do with violence against women and just rewards.

Where is this going? If the series is intended to be as bleak as indicated, then it might be a bit tough going, especially if we do not learn in these space settings anything new about gender politics, disabilities, exploration, and survival. At nine minutes in length and with characters that are either extremely unlikable or not yet fully fleshed out, “Ikarus - Part 1″ makes it difficult to come to any solid conclusions about this prequel or the upcoming series.

I enjoyed the music and the editing was well done, but I think it is too early to make any conclusive statements about the acting, directing, and other filmmaking mechanics. There is much to admire here and I look forward to the next part. There is some difficulty in introducing the back story and the universe for Venus Rises, but this is balanced by the novelty of original science fiction, filmmakers and participants that are obviously passionate about what they are doing, a fascinating and claustrophobic set, and at least one character I want to know more about.

I will be speaking at the Sunday, September 7 meeting of the Humanist Society of Greater Phoenix about “Images of Mars and Interplanetary Science.” This series of posts in preparation for the event will explore current spacecraft activities in planetary science.

After the astronomy revolt that left the solar system with eight planets, four dwarf planets, and a huge variety of other celestial objects, Mercury became the smallest planet.  Despite its newfound stature, Mercury remains an important destination for better understanding the inner and rocky solar system.  It also remains little explored, a state that has only recently been addressed by a new spacecraft with a comprehensive suite of instruments.

Credit: NSSDC Photo Gallery: Mercury - “Mercury Mosaic #1” taken by Mariner 10

Mercury can be difficult to see from the Earth despite being one of the brightest objects in the night sky.  The planet orbits close to the Sun, which also makes it a difficult destination to reach for spacecraft.  In fact, until recently only one spacecraft had visited Mercury.  In 1974 and 1975, Mariner 10 explored Mercury during three flybys.  Due to the geometry of the encounters, Mariner 10 was only able to image approximiately 45% of the planet’s surface.  The rest of the planet has been mapped at low resolution using Earth-based radar.

33 years later, MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) has finally provided the first close up images of surface features unexplored by Mariner 10.  The first flyby of the MESSENGER mission occurred on January 14, 2008.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington - “Mercury Shows Its True Colors” taken by MESSENGER

MESSENGER returns to Mercury for another pass on October 6, 2008 and again on September 29, 2009. However, on March 18, 2011 the mission gets especially interesting; the spacecraft will fire its thrusters to slip into orbit around Mercury. Although nearly all of the planet will have been mapped by this time, the closer proximity will allow a year-long study of the environment in which Mercury orbits the Sun and its tenuous atmosphere, as well as inspection of its geology and composition. Mercury hosts particularly interesting landmarks like the enormous Caloris impact basin and polar craters that may be shadowed enough to trap water in the form of ice despite the planet’s proximity so close to the Sun.

Mercury apparently has a massive iron core as a result of formation in the inner solar system and possibly due to a traumatic collision with another body that skinned the developing planet soon after differentiation. MESSENGER has spotted good evidence for volcanism to explain Mercury’s smooth lava plains, though it is likely that such activity occurred early in the planet’s history. Extensive systems of faults, ridges and cliffs as well as a spider-like formation of fractures within Caloris Basin show that Mercury has had a complex geological history.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington - “‘The Spider’ - Radial Troughs within Caloris” taken by MESSENGER

This history, among other data, may provide further information related to the formation of Mercury, the rocky inner planets, and the Solar System as a whole. Our Solar System is striking for the rocky composition of its inner planets and the gaseous and icy nature of its outer planets. Mercury is on the extreme end of this spectrum of planetary composition dictated by nearness to the developing Sun. Just how “dry” is Mercury? Why is the planet so dense? These questions and more can finally be addressed by the renewed exploration of the innermost planet. The next few years promise a wealth of discovery for scientists who have long clamored for a return visit to Mercury and finally saw their dreams realized after the turn of the century, and should help to keep feeding the public’s interest in planetary science and exploration.

More Information

• Mariner 10
• MESSENGER
• Previous Coverage of Mercury on Frontier Channel

Related Books

“Planetary Provenance” Posts

• Mercury
• Venus

On Friday, June 27, 2008 from 4:00 PM through 8:00 PM PDT at UCLA, scientists and other anti-aging luminaries will discuss “Aging: the Disease, the Cure, the Implications,” a Methuselah Foundation co-sponsored event. The ADCI event is open to the public and presents an opportunity for you to hear about the current state of radical life extension research. How close are we? What obstacles remain? What particular approaches are being taken?

While the event is free, registration is required. Simply click on the image above to register on the ADCI website. For $30.00, you can also attend a dinner that begins at 8:00 PM.

This free event is followed on Saturday, June 28 and Sunday, June 29 by a paid and technically focused Understanding Aging conference.

One of many new Cassini images received after yesterday’s successful Enceladus flyby. Image Credit: NASA/JPL/Space Science Institute - “W00043237.jpg“

Slow server speeds mark the arrival of new raw data on the Cassini-Huygens website taken during yesterday’s successful Enceladus flyby. In addition to the images, Cassini sampled the material in Enceladus’ water ice plumes erupting from the moon’s south pole. Images like the one above will be validated and calibrated while scientists pour over all the new data, hoping for insight into the process that leads to the geyser-like features.

Cassini took this image of Enceladus’ water ice plumes on November 27, 2005.  New pictures and other data from the most recent flyby on Wednesday, March 12, 2008 are expected on Thursday, March 13, 2008.  Image Credit: NASA/JPL/Space Science Institute - “Jet Blue“

NASA’s Cassini spacecraft has successfully completed the closest flyby of Saturn’s mysterious moon Enceladus yet. Coming as close as 52 kilometers (32.3 miles) from the surface of Enceladus, Cassini used its array of instruments to sample the water ice geysers that erupt from the moon’s south pole. The close, and somewhat risky, flyby maybe provide just the required data to begin understanding the source of these geysers. These data have started to arrive at the Earth and will be completely downloaded over the next several hours.

On Wednesday, March 12, 2008 around noon PST, Cassini flew away from Enceladus along the outer extent of the plume that surprised scientists just over two years ago. The surprise was due to the moon’s small size; small moons were generally thought to be inactive, as no internal forces would be present to drive any surface activities. Whatever is driving the spectacular activity on Enceladus remains a mystery.

Recently, two sources for the geysers have been proposed. The “dry” theory suggests that tidal forces along the “Tiger Stripes” fractures discovered at the moon’s south pole rub ice until it is heated sufficiently to escape. The “wet” theory suggest that these tidal forces instead heat a spot in the moon’s interior, resulting in enough heat to melt a lake or ocean of liquid water just below the surface. This pressurized water then escapes through the discovered fractures.

The latest flyby is intended to sample the geysers to determine which of these theories might be correct, or suggest alternative theories. An underground reservoir of liquid water and the forces required might create a potentially habitable location and an intriguing site to look for life. Cassini will look for the presence of sodium, among other elements and compounds, to support the “wet” theory.

Cassini is nearing the completion of its nominal four-year mission to explore Saturn, its rings, and its moons. The mission has been extended for two more years, allowing mission planners to take more risks. Scientists believe that the ice and other particles in the geyser are tiny enough to pose no harm to Cassini. If confirmed, this will allow scientists to fly Cassini closer yet in upcoming explorations of Enceladus. Raw data could start appearing on the Cassini website as early as 5:00 AM PST on Thursday and mission scientists hope to have a preliminary analysis of data completed by Thursday afternoon.

More Information

• Cassini-Huygens Website
  • Saturn’s Moons section
  • Enceladus Information
  • Press Release (NASA/JPL): “Cassini Spacecraft to Dive Into Water Plume of Saturn Moon“
  • Blog: Visiting Enceladus

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington - “MESSENGER’s First Look at Mercury’s Previously Unseen Side“

A heavily cratered side of the planet Mercury never before seen has been revealed by the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft. A single image was released by NASA this evening after the successful flyby of the innermost planet on Monday. Featuring rayed craters, a portion of one of the largest basins in the solar systems, and rings of dark material, the new image is one of over 2000 captured during the first flyby of Mercury in thirty-three years.

More data is expected to arrive on the Earth on Wednesday after MESSENGER’s scheduled contact over the Deep Space Network was postponed due to unexpected problems with other missions and a shift in priorities.  In addition to the global wide-angle image released this evening,  these data include approach and departure images that will be turned into movies and high resolution narrow-angle images taken from only 200 kilometers above Mercury’s surface during closest approach.

In 1975 Mariner 10 successfully completed its third and final flyby of Mercury after imaging less than 50 percent of the planet’s surface.  MESSENGER will complete this mapping task between yesterday’s flyby and two more flybys scheduled for October 06, 2008 and September 29, 2009.  Then, on March 18, 2011, MESSENGER will enter orbit around Mercury for a planned year-long science phase.

The data returned by MESSENGER are expected to answer several longstanding questions about Mercury.  MESSENGER will use its array of instruments protected by a sunshade to search for evidence of water ice trapped in deep and dark craters at the planet’s poles, a potentially counter intuitive finding given Mercury’s close proximity to the Sun.   Scientists will study the planet’s surface and composition as well as its inner structure.  Mercury has a dense core of iron thought to compose a more significant portion of the planet than the cores of the other inner planets do.  Why this should be the case is complicated by the presence of a magnetic field around Mercury.  Magnetic fields are thought to depend on molten cores, but models of Mercury indicate that due to its small size its core should have solidified by now.

More Information

• MESSENGER Website
  • Press Release and Image: “MESSENGER’s First Look at Mercury’s Previously Unseen Side“