Amazingly sharp image taken of lunar landscape
EUROPEAN SOUTHERN OBSERVATORY NEWS RELEASE
Posted: August 12, 2002

Thirty-three years after the first manned landing on the Moon, the ESO Very Large Telescope (VLT) has obtained what may be the sharpest image of the lunar surface ever recorded from the ground. It was made with the NAOS-CONICA (NACO) adaptive optics camera mounted on the ESO VLT 8.2-m YEPUN telescope at the Paranal Observatory.

Taruntius
A small area of the lunar surface, on the rim of the 56-km crater Taruntius. Photo: ESO
 
The photo shows an area about 700 km from the Apollo 11 landing site. The location is in the Eastern hemisphere, just North of the lunar equator, and right between two of the major "seas", Mare Tranquillitatis (Sea of Tranquillity) and Mare Foecunditatis (Sea of Fertility).

The field-of-view measures about 60 x 45 km^2 (taking into account the foreshortening because of the viewing angle), with part of a sunlit, 10-km wide crater named Cameron surrounded by a comparatively level terrain, bordered by some hills and, not least, with an incredible number of smaller craters.

The site of this NACO photo is situated at the rim of an older, rather eroded 56-km crater, Taruntius. A small part of the multiple walls of that crater are seen in the upper right corner and also to the left of the bottom centre of the above image. The centre of Taruntius is near the lower right corner of the photo. The rather flat terrain to the left in the photo corresponds to an "opening" in the crater walls.

At the time of the exposure, the Sun was approximately 7deg above the Western horizon to the left, and the shadows are therefore quite prominent, approx. 8 times longer than the elevation of the corresponding peaks and hills.

The nominal image sharpness is 0.07 arcsec, or about 130 metres on the lunar surface (in the N-S direction). Elevation differences of a few tens of metres only are therefore visible by the shadows they cast. The VLT image represents what an astronaut (with normal eye acuity of 1 arcmin) would see from 400 km above the surface.

Lunar surface formations
Located at 46deg East lunar longitude, 6deg North lunar latitude, this area is viewed from the VLT at an inclined angle and the craters therefore all appear as ellipses in the NACO image. However, taking into account the direction of the line-of-sight at the time of the observation, this view can be "rectified" by simple image processing. The corresponding "view from above" is shown below; most of the craters in the field now appear quite round.

Moon
A computer-processed version of the top image, in which the lunar surface is now viewed directly "from above". Photo: ESO
 
Many different types of lunar surface formations are visible in the VLT photo. In addition to the numerous impact craters of all sizes, there are also hills and ridges of a great variety of shapes, as well as a prominent "valley" (a "Rima", or fissure) that stretches nearly 50 km through the photo in East-West direction. It has been identified on earlier photos and as it is situated inside that crater, it was given the name "Rimae Taruntius" in 1985. It is very well resolved in this photo and resembles "Rima Hadley" that was visited by the Apollo 15 astronauts in 1971, but is much smaller. The mean width is about 600 metres (12 pixels). The bottom is in the shadows and the depth is therefore unknown. It is overlapped by several smaller craters that must have been caused by impacts after this depression was formed.

Measuring the length of the shadows, it is possible to infer the height of some of the formations. For instance, the shadows of the two peaks at the lower centre of the photo are about 4 km long, indicating that these formations are about 500 metres tall.

The surroundings
This area around Taruntius was imaged in 1994 by the NASA Clementine spacecraft when it mapped the entire lunar surface at 125-250 metres per pixel. The data led to the first complete map of the mineralogy (rock types) of the Moon.

Moon
Where is the NACO field at the Taruntius crater located on the Moon? A 400 x 400 km2 area surrounding this crater is shown in the right panel; it has been reproduced from a photo mosaique with 500-metre resolution based on exposures made in 1994 by the "Clementine" spacecraft in lunar orbit. Taruntius, Cameron and other craters in this area are identified in the diagram at the lower left. The area covered by the Clementine photo is outlined on a photo of the entire Moon (upper left), obtained at nearly the same phase as when the NACO image was made. Photo: ESO
 
The Clementine image shown here helps to identify the small area depicted by NACO. It is part of the Clementine Basemap Mosaic and has been observed with the onboard Ultraviolet/Visible camera through an optical filter centred at 750 nm. It covers a field-of-view of about 400 x 400 km^2, with a nominal resolution of about 500 metres. Many craters are well visible, including Taruntius with Cameron on the upper left sector of the multiple rim.

Testing the NAOS-CONICA instrument
This splendid VLT image is a by-product of the ongoing, thorough testing of the NAOS-CONICA (NACO) Adaptive Optics facility, recently installed at the 8.2-m YEPUN telescope, the fourth untit of the Very Large Telescope (VLT) at the ESO Paranal Observatory. This major astronomical instrument has already delivered other impressive views of the Universe.

Normally, NACO functions by "locking" on a point-like guide star, correcting the image smearing caused in the turbulent terrestrial atmophere by measuring the deformation of the recorded image of that star.

However, in the morning of April 30, 2002, shortly before sunrise, the astronomers and engineers working with NACO decided to do a test of wavefront sensing on an extended celestial object. For this, the giant telescope was turned towards the Moon, at that moment seen in the southern constellation of Ophiuchus, high above the western horizon at Paranal.

Guiding the advanced instrument on a sunlit lunar peak in the area between Mare Tranquillitatis and Mare Foecunditatis, a short exposure (0.22 seconds) was made through a narrow-band near-infrared filter (at wavelength 2.3 micrometers), with the adaptive optics (AO) activated in closed-loop mode. The telescope was set to track on that lunar mountain and the flexible AO mirror in NACO superbly "refocussed" the 25 x 25 arcsec2 field-of-view.

Although the atmosphere above Paranal was rather turbulent that morning - the nominal seeing was measured as 1.5 arcsec - and despite the use of an extended feature for the guiding, the NACO adaptive optics compensation achieved nearly theoretical image sharpness, about 0.068 arcsec for this waveband.

Images of other areas on the lunar surface may be attempted in the future with the VLT and NACO.

Apollo 15 DVD - offer ends soon
For a limited time only, preorder your Apollo 15 DVDs at a special discount price. Two- and six-disc editions of this unique DVD are coming soon.
 U.S. STORE
 U.K. & WORLDWIDE STORE

Hubble
Astronomy Now presents Hubble: the space telescope's view of the cosmos. A collection of the best images from the world’s premier space observatory.
 U.S. STORE
 U.K. & WORLDWIDE STORE
Apollo 16
NEW! The latest in Apogee Book's acclaimed NASA Mission Reports series features the Apollo 16 expedition to the lunar highland area of Descartes. Includes CD-ROM.
 U.S. STORE
 U.K. & WORLDWIDE STORE

Expedition 20
The official embroidered patch for the International Space Station Expedition 20 crew is now available from our stores.
 U.S. STORE
 WORLDWIDE STORE

Current Shuttle Mission Patch
The official embroidered patch for shuttle Atlantis' flight to deliver critical spare equipment to the space station.
 U.S. STORE
 WORLDWIDE STORE



Ares Patch
The Ares Project will develop two new rockets to launch astronauts back to the Moon under NASA's Vision for Exploration. The Ares 1 will employ a single space shuttle solid rocket booster to loft the Orion crew capsule. The gigantic Ares 5 will haul the equipment and cargo needed for such lunar voyages. This is the Ares emblem.
 U.S. STORE


One Giant Leap
Hosted by Corbin Bernsen, this award winning documentary marks the 50th anniversary of the U.S. space agency and features exclusive interviews with veteran astronauts.
 U.S. STORE
 WORLDWIDE STORE

Expedition 21
The official embroidered patch for the International Space Station Expedition 21 crew is now available from our stores.
 U.S. STORE
 WORLDWIDE STORE

An insider's view of how Apollo flight controllers operated and just what they faced when events were crucial.
 Choose your store:
U.S.

Soviet Space
For the first time ever available in the West. Rocket & Space Corporation Energia: a complete pictorial history of the Soviet/Russian Space Program from 1946 to the present day all in full color. Available from our store.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Viking patch
This embroidered mission patch celebrates NASA's Viking Project which reached the Red Planet in 1976.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Apollo 7 DVD
For 11 days the crew of Apollo 7 fought colds while they put the Apollo spacecraft through a workout, establishing confidence in the machine what would lead directly to the bold decision to send Apollo 8 to the moon just 2 months later.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Gemini 12
Gemini 12: The NASA Mission Reports covers the voyage of James Lovell and Buzz Aldrin that capped the Gemini program's efforts to prove the technologies and techniques that would be needed for the Apollo Moon landings. Includes CD-ROM.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Station Calendar
NEW! This beautiful 12" by 12" wall calendar features stunning images of the International Space Station and of the people, equipment, and space craft associated with it, as it takes shape day by day in orbit high above the Earth.
 U.S. STORE
 U.K. & WORLDWIDE STORE

Get e-mail updates
Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop (privacy note: your e-mail address will not be used for any other purpose).
Enter your e-mail address:

INDEX | PLUS | NEWS ARCHIVE | LAUNCH SCHEDULE
ASTRONOMY NOW | STORE

ADVERTISE

© 2009 Spaceflight Now Inc.