On this day in 1997, communication with Mars rover Sojourner was lost.
Named for abolitionist and women’s rights activist Sojourner Truth, NASA’s Sojourner rover landed on Mars on July 4, 1997. Unlike previous landing systems that used conventional rockets to decelerate, the Sojourner rover used a parachute and a system of airbags to slow down before the rover dropped roughly 100 feet to the planet’s surface. This system comprised of the Pathfinder lander, which was renamed the Carl Sagan Memorial Station after successfully delivering the rover. Sagan, a major proponent of the exploration of Mars, passed away shortly after the Mars Pathfinder mission launched on its way to the Red Planet.
Sojourner then set about its mission to analyze nearby rocks on the surface. Compositional analysis revealed that silica was found in higher concentrations in rocks than the surrounding area. Being found in igneous rocks, such a presence of silica was a hint that Mars may have had a more interesting geological history than was previously thought. Sojourner also sent pictures of the Martian surface back to NASA, while Pathfinder took photographs of the Martian sky. Among the photos from Sojourner were images showing rounded pebbles and conglomerate rocks indicating that different types of soil had been mixed in the past—evidence of a formerly water-rich planet.
Originally scheduled to operate for 7 sols (1 sol is about 40 minutes longer than a day on Earth), Sojourner had the possibility of extending its mission to 30 sols. In total, Sojourner operated for 83 sols before communications were lost on September 27, 1997. In that time, it covered just over 100 meters of the Martian surface.
Learn more about Sojourner here: http://goo.gl/i1axt
Hump-nosed lizard (Lyriocephalus scutatus)
Lyriocephalus scutatus is a species of lizard within the agamid family. It is the largest agamid endemic to Sri Lanka and lives in dense wet zone forests. It is also called the Hump-nosed Lizard. Inhabited in forests with high canopy, it also enters home gardens, and is found on low trees as well as on the ground. Active at day, it ascends higher reaches of trees to sleep at night. The typical threat posture is open-mouth gape, revealing the bright red lining of the oral cavity. This species is also known to feign death when picked up. Its diet comprises essentially of earthworms and also arthropods, including termites, butterflies, and moths. It is considered as “Near threatened" by the IUCN.
The sun is a huge thermo-nuclear reactor, fusing hydrogen atoms into helium and producing million degree temperatures and intense magnetic fields. The outer layer of the sun near its surface is like a pot of boiling water, with bubbles of hot, electrified gas—electrons and protons in a fourth state of matter known as plasma—circulating up from the interior and bursting out into space. The steady stream of particles blowing away from the sun is known as the solar wind.
- For more information click here.
Asa Smith. Celestial Illustrations from Smith’s Illustrated Astronomy. 1851.
Wood engravings with hand highlighting, written by the principal of Public School No. 12 in New York City with the goal “to present all the distinguishing principles in physical Astronomy with as few words as possible”.