NASA image of the day (imatge del dia, NASA)

Spacecraft attempting to land on an unfamiliar surface need to perform a maneuver called “deep throttling" -- a step that allows the vehicle to precisely throttle down to perform a smooth, controlled landing. NASA and industry partners have demonstrated this type of engine control capability to help design a more reliable and robust descent engine that could be used to land space exploration vehicles on the moon, an asteroid or another planet. The Common Extensible Cryogenic Engine, also known as CECE, recently completed the fourth and final series of hot-fire tests on a 15,000-pound thrust class cryogenic technology demonstrator rocket engine, increasing the throttling capability by 35 percent over previous tests. This test series demonstrated this engine could go from a thrust range of 104 percent power down to 5.9 percent. This equates to an unprecedented 17.6:1 deep-throttling capability, which means this cryogenic engine can quickly throttle up and down. Image Credit: NASA

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full 360-degree view of the rover's surroundings after a drive on the 2,220th Martian day, or sol, of its mission (April 22, 2010). Opportunity launched on July 7, 2003, on a mission slated to last 90 days, landing on Mars in January 2004. The rover has exceeded its mission parameters by more than 2,200 days as its exploration of the Red Planet continues. Opportunity took some of the component images for this mosaic on Sol 2220, after the drive, and the rest on Sol 2221. Wind-formed ripples of dark sand make up much of the terrain surrounding this position. Patches of outcrop are visible to the south. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Image Credit: NASA/JPL-Caltech

Like an Independence Day fireworks display, a young, glittering collection of stars looks like an aerial burst. The cluster is surrounded by clouds of interstellar gas and dust -- the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. This environment is not as peaceful as it looks. Ultraviolet radiation and violent stellar winds have blown out an enormous cavity in the gas and dust enveloping the cluster, providing an unobstructed view of the cluster. Most of the stars in the cluster were born around the same time but differ in size, mass, temperature, and color. The course of a star's life is determined by its mass, so a cluster of a given age will contain stars in various stages of their lives, giving an opportunity for detailed analyses of stellar life cycles. NGC 3603 also contains some of the most massive stars known. These huge stars live fast and die young, burning through their hydrogen fuel quickly and ultimately ending their lives in supernova explosions. Star clusters like NGC 3603 provide important clues to understanding the origin of massive star formation in the early, distant universe. Astronomers also use massive clusters to study distant starbursts that occur when galaxies collide, igniting a flurry of star formation. The proximity of NGC 3603 makes it an excellent lab for studying such distant and momentous events. Image Credit: NASA, ESA, R. O'Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA)

Space shuttle Discovery and its seven-member crew launched at 2:38 p.m. EDT on July 4, 2006 to begin their journey to the International Space Station during the STS-121 mission. The shuttle made history as it was the first human-occupied spacecraft to launch on Independence Day. During the 12-day mission, the crew tested new equipment and procedures that increase the safety of the orbiters. It also performed maintenance on the space station and delivered supplies, equipment and a new Expedition 13 crew member to the station. This mission carried on analysis of safety improvements that debuted on the Return to Flight mission, STS-114, and built upon those tests. Image Credit: NASA

Astronaut John W. Young, commander of the Apollo 16 lunar landing mission, leaps from the lunar surface as he salutes the United States flag at the Descartes landing site during the first Apollo 16 extravehicular activity. Astronaut Charles M. Duke Jr., lunar module pilot, took this picture. The Lunar Module "Orion" is on the left. The Lunar Roving Vehicle is parked beside Orion and the object behind Young (in the shadow of the Lunar Module) is the Far Ultraviolet Camera/Spectrograph. Stone Mountain dominates the background of this lunar scene. Image Credit: NASA

Mars rover Curiosity, the centerpiece of NASA's Mars Science Laboratory mission, is coming together for extensive testing prior to its late 2011 launch. This image taken June 29, 2010, shows the rover with the mobility system -- wheels and suspension -- in place after installation on June 28 and 29. Spacecraft engineers and technicians are assembling and testing the rover in a large cleanroom at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Curiosity's six-wheel mobility system, with a rocker-bogie suspension system, resembles the systems on earlier, smaller Mars rovers, but for Curiosity, the wheels will also serve as landing gear. Each wheel is half a meter (20 inches) in diameter. Image Credit: NASA/JPL-Caltech

There are two possible explanations for this 'slingshot' in space: kickback by a triple black hole system, or the effects of gravitational waves produced after two supermassive black holes merged a few million years earlier. The discovery of this object comes from a large, multi-wavelength survey, known as the Cosmic Evolution Survey (COSMOS). This survey includes data from Chandra, HST, XMM- Newton, as well as ground-based observatories. Of the 2,600 X-ray sources found in COSMOS, only one -- named CID-42 and located in a galaxy about 3.9 billion light years away -- coincides with two very close, compact optical sources. Image Credits: X-ray: NASA/CXC/SAO/F.Civano et al. Optical: NASA/STScI

The Mercury 7 astronauts examine their 'couches.' Each astronaut's couch was molded to fit his body to help withstand the G-loads of the launch. Plaster casts of the astronauts were created in order to properly mold the couches. Left to right are Alan Sheppard, John Glenn, Walter Schirra, Scott Carpenter, Gordon Cooper, Deke Slayton, Gus Grissom and Bob Gilruth. Gilruth was director of the Space Task Group, which planned and managed the Mercury Project. Image Credit: NASA

The surface of Saturn's moon Dione is rendered in crisp detail against a hazy, ghostly Titan. Visible in this image are hints of atmospheric banding around Titan's north pole. The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on April 10, 2010. The view was acquired at a distance of approximately 1.8 million kilometers (1.1 million miles) from Dione and 2.7 million kilometers (1.7 million miles) from Titan. Scale in the original image was 11 kilometers (7 miles) per pixel on Dione and 16 kilometers (10 miles) on Titan. The image has been magnified by a factor of 1.5 and contrast-enhanced to aid visibility. Image Credit: NASA/JPL/Space Science Institute

NASA remembers Roy Estess, former Stennis Space Center Director, who passed away on June 25, 2010. Estess had a 37-year career at NASA, which began in 1966 where he was a test engineer at NASA's Stennis Space Center, known then as the Mississippi Test Facility, and worked on the engines for the Apollo Program. In 1989, he was named center director of Stennis and served in that role until 2002. He also served as acting center director of Johnson Space Center. In this image from 2001, Johnson Space Center Acting Director Roy Estess (right) greets the Expedition 3 and STS-108 crews during return ceremonies. Seated (from left) are Nikolai Zubov, Deputy Director for Logistics and Procurement, Gagarin Cosmonaut Training Center, Star City, Russia; Expedition 3 commander Frank Culbertson; and Expedition 3 flight engineers Mikhail Tyurin and Vladimir N. Dezhurov. Image Credit: NASA

This future aircraft design concept for supersonic flight over land comes from the team led by the Lockheed Martin Corporation. The team's simulation shows possibility for achieving overland flight by dramatically lowering the level of sonic booms through the use of an "inverted-V" engine-under wing configuration. Other revolutionary technologies help achieve range, payload and environmental goals. This supersonic cruise concept is among the designs presented in April 2010 to the NASA Aeronautics Research Mission Directorate for its NASA Research Announcement-funded studies into advanced aircraft that could enter service in the 2030-2035 timeframe. Image credit: NASA/Lockheed Martin Corporation

Exhibits highlight NASA's Earth and space science portfolio, cutting-edge aeronautics research and technology development and continued leadership in human space flight and exploration for NASA Day on the Hill in the Rayburn Foyer, Rayburn House Office Building, on June 23, 2010. Pictured is Scarab, a new generation lunar rover designed to assist astronauts take rock and mineral samples and explore the lunar surface. This lunar rover is being evaluated to demonstrate a combined drilling and science rover platform for lunar exploration. Image Credit: NASA/Carla Cioffi

The Japan Aerospace Exploration Agency’s Hayabusa spacecraft streaked across the sky like a saber of light through the clouds as it re-entered Earth’s atmosphere over the Woomera Test Range in Australia. In Kingoonya, the spacecraft’s re-entry was visible to the human eye for only 15 seconds. Image Credit: NASA/Ed Schilling

Today, our sun reaches its northernmost point in planet Earth's sky. Called a solstice, the date traditionally marks a change of seasons -- from spring to summer in Earth's Northern Hemisphere and from fall to winter in Earth's Southern Hemisphere. In this image from 2007, NASA's Solar TErrestrial RElations Observatory (STEREO) satellites provided the first three-dimensional images of the sun. STEREO, a two-year mission that launched October 2006, provided a unique and revolutionary view of the Sun-Earth System. Image Credit: NASA/JPL-Caltech/NRL/GSFC

On June 18, 1983, a young physicist from California took her seat aboard the space shuttle and launched into history. On that date, Sally Ride became the first American woman in space as a mission specialist on STS-7. In this image Ride monitors control panels from the pilot's chair on the Flight Deck. Image Credit: NASA

The bulkhead and nosecone of the Orion spacecraft are joined using friction stir welding at NASA's Michoud Assembly Facility. Nondestructive evaluations will validate the strength and integrity of the weld before the spacecraft is prepped for ground testing in flight-like environments, including static vibration, acoustics and water landing tests. Image Credit: NASA

The Soyuz TMA-19 rocket launched from the Baikonur Cosmodrome in Kazakhstan on Wednesday, June 16, 2010, carrying Expedition 24 NASA astronauts Shannon Walker and Douglas Wheelock, and Soyuz Commander Fyodor Yurchikhin to the International Space Station. Their Soyuz TMA-19 rocket launched at 3:35 a.m Kazakhstan time, or 5:35 p.m EDT. Image Credit: NASA/Carla Cioffi

This image from 1967 shows the S-II stage of the Saturn V rocket as it was hoisted onto the A-2 test stand at the Mississippi Test Facility (now the Stennis Space Center). This was the second stage of the 364-foot tall moon rocket, which was powered by five J-2 engines. Image Credit: NASA

The Soyuz TMA-19 spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, Sunday, June 13, 2010. The launch of the Soyuz spacecraft with Expedition 24 astronauts Shannon Walker and Doug Wheelock, and Russian Soyuz Commander Fyodor Yurchikhin is scheduled for 5:35 p.m. EDT on Tuesday, June 15. Image Credit: NASA/Carla Cioffi

NASA Administrator Charles Bolden spoke with teachers and middle school students during the kick off of NASA's Summer of Innovation program at the Jet Propulsion Laboratory in Pasadena, Calif., Thursday, June 10, 2010. Through the program, NASA will engage thousands of middle school students and their teachers in stimulating math and science-based education programs with the goal of increasing the number of future scientists, mathematicians and engineers. Image Credit: NASA/Bill Ingalls