Deep Impact (spacecraft)
Deep Impact was a NASA spacecraft launched on January 13, 2005, with the primary mission of studying the composition of comets. The mission involved a unique approach: the spacecraft released a copper impact probe that collided with the comet Tempel 1 on July 4, 2005. This dramatic impact created a crater and released debris, allowing scientists to gather vital data about the comet's interior, which was found to be mostly porous and composed of about 75% empty space. The mission was considered a significant success, as it provided unprecedented insights into the origins of the solar system.
Following its initial mission, Deep Impact was re-purposed as EPOXI, focusing on observing nearby stars for exoplanets and conducting a flyby of comet Hartley 2 in 2010. The spacecraft's journey lasted nearly nine years, during which it traveled approximately 4.7 billion miles and captured over 500,000 photographs. Although Deep Impact experienced a loss of communication in 2013 due to a suspected software glitch, its contributions significantly advanced the scientific understanding of comets and their formation.
Deep Impact (spacecraft)
Deep Impact was a spacecraft launched by the National Aeronautics and Space Administration (NASA) in 2005. It was designed to study the composition of a comet by smashing a probe into the orbiting ball of frozen gas, rock, and ice and observing the debris released by the impact. The spacecraft accomplished its primary mission on July 4, 2005, when it released a probe to collide with a comet called Tempel 1. The resulting impact provided scientists with valuable data that advanced humans' understanding of the solar system. After the mission, Deep Impact was able to observe several other comets before a computer problem permanently disabled the spacecraft in 2013.
Brief History
The Deep Impact spacecraft was produced at a cost of $267 million and was launched onboard a Boeing Delta II rocket on January 13, 2005. Deep Impact actually consisted of two vehicles, a spacecraft designed to fly by a comet and a copper impact probe measuring 39 inches by 39 inches and weighing 820 pounds. The spacecraft took 172 days to travel 268 million miles to rendezvous with its target, a 3.7-mile-wide comet named Tempel 1. Comets are chunks of ice, rock, and frozen gas left over from the formation of the solar system 4.5 billion years ago. Scientists often compare them to giant, dirty snowballs hurtling through space. The Tempel 1 comet was named after Wilhelm Tempel, the German astronomer who first discovered it in 1876.
As Deep Impact neared Tempel 1, it deployed the probe, which maneuvered itself into the path of the comet. On July 4, 2005, the probe slammed into the comet at 22,800 miles per hour, emitted a brief flash, and blasted a 500-foot crater into Tempel 1. The impact destroyed the probe and threw up a cloud of debris. The main spacecraft then flew into the cloud to gather scientific data.
Scientists on Earth had observed comets for years but were never able to analyze their interiors. Data sent back by Deep Impact not only allowed scientists to "see" what was inside these deep space objects, but also provided clues to how the solar system originated. According to CNN, chief mission scientist Mike A'Hearn of the University of Maryland said that Deep Impact "revolutionized" humans' understanding of comets.
Among the findings, scientists discovered that Tempel 1 was mostly made up of nothing. The relatively large size of the crater told researchers the comet's interior was porous and consisted of about 75 percent empty space, similar to the consistency of freshly fallen snow. A more solid, rocky surface would have yielded a smaller crater. They also discovered that the gases released from the comet were made up of different substances depending on the part of the comet they originated from. The gases emitted near the equator were mostly water and water vapor, while carbon dioxide streamed out from the southern polar region. This suggested that comets consisted of both frozen water and frozen carbon dioxide, also known as dry ice.
Further Missions
Deep Impact continued to study Tempel 1 for a few weeks. Scientists deemed the mission a success and switched off the spacecraft to conserve its power. They woke it up occasionally over the course of two years to make sure it still worked. In 2007, NASA engineers determined Deep Impact still contained enough fuel to extend its mission. They renamed the mission EPOXI to represent the combination of two specific goals. The first was a plan to use the spacecraft's equipment to study nearby stars in the search for planets outside the solar system. This part of the mission was called Extrasolar Planet Observations and Characterization (EPOCh). The second phase was a flyby of the comet Hartley 2, which was called the Deep Impact Extended Investigation (DIXI). On December 12, 2007, scientists sent the craft on a course close to Earth to get a speed boost from the planet's gravity and then off on its nearly three-year voyage.
The spacecraft met up with Hartley 2 on November 4, 2010, and flew within five hundred miles of the comet. Pictures it transmitted back to Earth revealed an object shaped like a chicken drumstick, and the information it provided added to the knowledge learned from Tempel 1. Scientists discovered that much of the water surrounding a comet was driven out by carbon dioxide released from its interior. They also found that some comets formed closer to the Sun at the birth of the solar system than previously thought. For centuries, scientists believed comets formed out beyond the edge of the solar system and traveled inward toward the Sun.
The journey to Hartley 2 used up most of Deep Impact's fuel, but the spacecraft was still useful. It remained in orbit around the Sun and was used as a platform to study several other celestial objects, including the Moon, planets, and other comets. Observations made by Deep Impact helped scientists detect the presence of water on Earth's moon. In 2012, the spacecraft photographed comet Garrard from a distance, and it turned its attention to comet ISON in 2013. The pictures Deep Impact obtained from ISON—a comet eventually torn apart after it passed too close to the Sun—turned out to be some of the last sent from the spacecraft.
On August 14, 2013, scientists tuned in to listen to Deep Impact, but the spacecraft never responded. They tried to contact it for a month before eventually giving up and declaring the mission officially lost. NASA engineers theorized Deep Impact was disabled by a software glitch that caused it to lose its orientation with Earth and suffer a catastrophic loss of power. In almost nine years, the spacecraft traveled 4.7 billion miles through space, took more than 500,000 photographs, and delivered more data than scientists had ever hoped for.
Bibliography
Beatty, Kelly. "Deep Impact's New Assignments." Sky & Telescope, 13 Dec. 2007, www.skyandtelescope.com/astronomy-news/deep-impacts-new-assignments/. Accessed 25 Nov. 2024.
"Deep Impact (EPOXI)." National Aeronautics and Space Administration, 23 Sept. 2021, solarsystem.nasa.gov/missions/deep-impact-epoxi/in-depth/. Accessed 25 Nov. 2024.
Lakdawalla, Emily. "Venerable Deep Impact Spacecraft Has Photographed Comet ISON." The Planetary Society, 5 Feb. 2013, www.planetary.org/blogs/emily-lakdawalla/2013/02051500-deep-impact-ison.html. Accessed 25 Nov. 2024.
Tytell, David. "Deep Impact Makes a Big Splash." Sky & Telescope, 5 July 2005, www.skyandtelescope.com/astronomy-news/deep-impact-makes-abig-splash/. Accessed 25 Nov. 2024.
Watkins, Tom. "NASA Deep-Sixes Deep Impact Comet Hunter." CNN, 20 Sept. 2013, www.cnn.com/2013/09/20/us/nasa-comet-hunter/. Accessed 25 Nov. 2024.