This illustration shows the events that occur in the final minutes of the nearly seven-month journey that NASA’s Perseverance rover takes to Mars. Hundreds of critical events must execute perfectly and exactly on time for the rover to land on Mars safely on Feb. 18, 2021.
Entry, Descent, and Landing, or “EDL,” begins when the spacecraft reaches the top of the Martian atmosphere, traveling nearly 12,500 mph (20,000 kph). It ends about seven minutes later, with Perseverance stationary on the Martian surface. Perseverance handles everything on its own during this process. It takes more than 11 minutes to get a radio signal back from Mars, so by the time the mission team hears that the spacecraft has entered the atmosphere, in reality, the rover is already on the ground.
NASA’s Jet Propulsion Laboratory in Southern California built and will manage operations of the Mars 2020 Perseverance rover for NASA.
Saturn is truly the lord of the rings in this latest portrait from NASA’s Hubble Space Telescope, captured on July 4, 2020, when the opulent giant world was 839 million miles from Earth. This new Saturn image was taken during summer in the planet’s northern hemisphere.
Hubble found a number of small atmospheric storms. These are transient features that appear to come and go with each yearly Hubble observation. The banding in the northern hemisphere remains pronounced as seen in Hubble’s 2019 observations, with several bands slightly changing color from year to year. The ringed planet’s atmosphere is mostly hydrogen and helium with traces of ammonia, methane, water vapor, and hydrocarbons that give it a yellowish-brown color.
Hubble photographed a slight reddish haze over the northern hemisphere in this color composite. This may be due to heating from increased sunlight, which could either change the atmospheric circulation or perhaps remove ices from aerosols in the atmosphere. Another theory is that the increased sunlight in the summer months is changing the amounts of photochemical haze produced. “It’s amazing that even over a few years, we’re seeing seasonal changes on Saturn,” said lead investigator Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Conversely, the just-now-visible south pole has a blue hue, reflecting changes in Saturn’s winter hemisphere.
Hubble’s sharp view resolves the finely etched concentric ring structure. The rings are mostly made of pieces of ice, with sizes ranging from tiny grains to giant boulders. Just how and when the rings formed remains one of our solar system’s biggest mysteries. Conventional wisdom is that they are as old as the planet, over 4 billion years. But because the rings are so bright – like freshly fallen snow – a competing theory is that they may have formed during the age of the dinosaurs. Many astronomers agree that there is no satisfactory theory that explains how rings could have formed within just the past few hundred million years. “However, NASA’s Cassini spacecraft measurements of tiny grains raining into Saturn’s atmosphere suggest the rings can only last for 300 million more years, which is one of the arguments for a young age of the ring system,” said team member Michael Wong of the University of California, Berkeley.
Two of Saturn’s icy moons are clearly visible in this exposure: Mimas at right, and Enceladus at bottom.
This image is taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets. In Saturn’s case, astronomers continue tracking shifting weather patterns and storms.
On Monday, February 10, at 7:30 p.m. the Cuyahoga Astronomical Association (CAA) will conduct its monthly club meeting. The meeting will feature a talk by CAA member Kai Getrost, a member of the special NASA teams that performed occultation studies in support of NASA’s New Horizon’s space probe to “Ultima Thule.” He is currently working in support of NASA’s Lucy Mission to explore Jupiter’s Trojan Asteroids. The Lucy spacecraft will launch in October 2021 and, with boosts from Earth’s gravity, will complete a 12-year journey to seven different asteroids.
As part of the NASA science teams in support of the New Horizons and Lucy Missions, Getrost has traveled to South America and to Australia to help gather occultation data used to help guide the spacecraft.
The CAA’s monthly meetings are held on the second Monday of every month except December at 7:30 p.m. in the Cleveland Metroparks’ Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio. Meeting programs are open to the public. Following the presentation and a brief social break, the club will conduct its membership business meeting.