NASA’s Juno spacecraft has provided the first close-ups of Jupiter’s largest moon in two decades. Juno zoomed past icy Ganymede on Monday, passing within 645 miles (1,038 kilometers). The last time a spacecraft came that close was in 2000 when NASA’s Galileo spacecraft swept past our solar system’s biggest moon. Read:NASA picks Venus as hot spot for two new robotic missions NASA released Juno’s first two pictures Tuesday, highlighting Ganymede’s craters and long, narrow features possibly related to tectonic faults. One shows the moon’s far side, opposite the sun. “This is the closest any spacecraft has come to this mammoth moon in a generation,” said Juno’s lead scientist, Scott Bolton of the Southwest Research Institute in San Antonio. “We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder – the only moon in our solar system bigger than the planet Mercury.” Read:Chinese cargo spacecraft docks with orbital station Ganymede is one of 79 known moons around Jupiter, a gas giant. Italian astronomer Galileo Galilei discovered Ganymede in 1610, along with Jupiter’s three next-biggest moons. Launched a decade ago, Juno has been orbiting Jupiter for five years.

NASA is returning to sizzling Venus, our closest yet perhaps most overlooked neighbor, after decades of exploring other worlds. The space agency’s new administrator, Bill Nelson, announced two new robotic missions to the solar system’s hottest planet, during his first major address to employees Wednesday. Read:Chinese cargo spacecraft docks with orbital station “These two sister missions both aim to understand how Venus became an inferno-like world capable of melting lead at the surface,” Nelson said. One mission named DaVinci Plus will analyze the thick, cloudy Venusian atmosphere in an attempt to determine whether the inferno planet ever had an ocean and was possibly habitable. A small craft will plunge through the atmosphere to measure the gases. It will be the first U.S.-led mission to the Venusian atmosphere since 1978. The other mission, called Veritas, will seek a geologic history by mapping the rocky planet’s surface. Read:Forecast: 40% chance Earth to be hotter than Paris goal soon “It is astounding how little we know about Venus,” but the new missions will give fresh views of the planet’s atmosphere, made up mostly of carbon dioxide, down to the core, NASA scientist Tom Wagner said in a statement. “It will be as if we have rediscovered the planet.” NASA’s top science official, Thomas Zurbuchen, calls it “a new decade of Venus.” Each mission — launching sometime around 2028 to 2030 — will receive $500 million for development under NASA’s Discovery program. The missions beat out two other proposed projects, to Jupiter’s moon Io and Neptune’s icy moon Triton. The U.S. and the former Soviet Union sent multiple spacecraft to Venus in the early days of space exploration. NASA’s Mariner 2 performed the first successful flyby in 1962, and the Soviets’ Venera 7 made the first successful landing in 1970. Read: Cosmic 2-for-1: Total lunar eclipse combines with supermoon In 1989, NASA used a space shuttle to send its Magellan spacecraft into orbit around Venus. The European Space Agency put a spacecraft around Venus in 2006.

China landed a spacecraft on Mars for the first time on Saturday, a technically challenging feat more difficult than a moon landing, in the latest advance for its ambitious goals in space. Plans call for a rover to stay in the lander for a few days of diagnostic tests before rolling down a ramp to explore an icy area of Mars known as Utopia Planitia. It will join an American rover that arrived at the red planet in February. China’s first Mars landing follows its launch last month of the main section of what will be a permanent space station and a mission that brought back rocks from the moon late last year. “China has left a footprint on Mars for the first time, an important step for our country’s space exploration,” the official Xinhua News Agency said in announcing the landing on one of its social media accounts. Read:Biggest space station crowd in decade after SpaceX arrival The U.S. has had nine successful landings on Mars since 1976. The Soviet Union landed on the planet in 1971, but the mission failed after the craft stopped transmitting information soon after touchdown. A rover and a tiny helicopter from the American landing in February are currently exploring Mars. NASA expects the rover to collect its first sample in July for return to Earth in a decade. China has landed on the moon before but landing on Mars is a much more difficult undertaking. Spacecraft must use shields for protection from the searing heat of reentry and both retro-rockets and parachutes to slow enough to prevent a crash landing. The parachutes and rockets must be deployed at precise times to land at the designated spot. Only mini-retro rockets are required for a moon landing, and parachutes alone are sufficient for returning to Earth. Xinhua said the entry capsule entered the Mars atmosphere at an altitude of 125 kilometers (80 miles), initiating what it called “the riskiest phase of the whole mission.” A 200 square meter (2,150 square foot) parachute was deployed and later jettisoned, and then a retro-rocket was fired to slow the speed of the craft to almost zero, Xinhua said. The craft hovered about 100 meters (330 feet) above the surface to identify obstacles before touching down on four buffer legs. “Each step had only one chance, and the actions were closely linked. If there had been any flaw, the landing would have failed,” said Geng Yan, an official at the China National Space Administration, according to Xinhua. Touchdown was at 7:18 a.m. Beijing time (23:18 GMT; 7:18 p.m. EDT), according to the State Administration of Science. Technology and Industry for National Defense. The distance between Earth and Mars caused a delay for mission control in Beijing to confirm its success. Chinese President Xi Jinping, in a congratulatory letter to the mission team, called the landing “an important step in our country’s interplanetary exploration journey, realizing the leap from Earth-moon to the planetary system and leaving the mark of the Chinese on Mars for the first time. ... The motherland and people will always remember your outstanding feats!” NASA Associate Administrator Thomas Zurbuchen tweeted his congratulations, saying, “Together with the global science community, I look forward to the important contributions this mission will make to humanity’s understanding of the Red Planet.” China’s Mars landing was the top trending topic on Weibo, a leading social media platform, as people expressed both excitement and pride. The Tianwen-1 spacecraft has been orbiting Mars since February, when it arrived after a 6 1/2-month journey from Earth. Xinhua described the mission as China’s first planetary exploration. Read:China names Mars rover for traditional fire god The rover, named after the Chinese god of fire Zhurong, is expected to be deployed for 90 days to search for evidence of life. About the size of a small car, it has ground-penetrating radar, a laser, and sensors to gauge the atmosphere and magnetic sphere. China’s space program has proceeded in a more cautious manner than the U.S. and the Soviet Union during the height of their space race. The launch of the main module for its space station in April is the first of 11 planned missions to build and provision the station and send up a three-person crew by the end of next year. While successful, the uncontrolled return to Earth of the launch rocket drew international criticism including from NASA Administrator Bill Nelson. China has said it wants to land people on the moon and possibly build a scientific base there. No timeline has been released for such projects. A space plane is also reportedly under development.