Ahmed0033

Our Moon is like a desert with plains, mountains, and valleys. It also has many craters, holes created when space rocks hit the surface at a high speed. There is no air to breathe on the Moon. The Moon travels around the Earth in an oval-shaped orbit.

We only ever see one side of the Moon from Earth. That's because the interplay of gravity between Earth and Moon slows the Moon into a rotation that paces its own. The Moon rotates, but it rotates at the same speed that it orbits around Earth. This keeps the same side always turned toward us.It is a spherical rocky body, probably with a small metallic core, revolving around Earth in a slightly eccentric orbit at a mean distance of about 384,000 km (238,600 miles). Its equatorial radius is 1,738 km (1,080 miles).We all know that in space there is no medium in which sound can travel. There is no solid, no liquid and no gas. So, on the moon, we cannot hear any sound.

In this episode, we will tell you the amazing story of OSIRIS-REx and Bennu, a NASA mission that collected and returned the largest asteroid.

The story of this video begins in March 2020, just at the start of the pandemic. “I remember taking breaks, my lunchtime walk around my neighborhood, and sort of thinking up some shots, like how we would first approach the asteroid,” said Dan Gallagher, producer and writer at NASA’s Goddard Space Flight Center. The video, which now has just under one million views on YouTube, utilizes advanced graphics techniques to portray the close-to-home asteroid. Unlike the other videos being featured at SIGGRAPH, Gallagher and Elkins used actual scientific data from NASA’s OSIRIS-REx spacecraft to create “Tour of Asteroid Bennu.” OSIRIS-REx, which launched on September 6, 2016, reached the asteroid in 2018 and gathered imagery, lidar, laser ranging, data, and other forms of data while in orbit. The spacecraft even briefly touched down on the asteroid to take a sample in October 2020. Depicted by an orange loop around the asteroid, the beginning of the video highlights the location of the spacecraft while in orbit, which is based on actual mission data. The 3D model of the asteroid comes primarily from lidar data, but as the camera takes the viewer in closer to Bennu, the model also incorporates global image mosaics and global brightness maps. “We had this idea to do for Bennu what Ernie Wright had done in his Tour of the Moon, which was to take terrain data, and high-resolution imagery and make a really awesome flyover of Bennu and put the camera down as close as we could to the surface and fly it over some of the new features,” Gallagher said. The tour of the asteroid covers six sites in depth, stating the name of each site as well as giving a 3D view of the surroundings. According to a behind-the-scenes video diving into the making of “Tour of Asteroid Bennu,” the model of the asteroid began as a low-resolution polygon model, limiting how close the camera could get to the surface. As the OSIRIS-REx mission continued, more data was collected, until the model was composed of five-centimeter resolution tiles. “Every time we would get new high-resolution models of the asteroid, we would try pushing the camera in closer and closer in those regions,” Elkins said. When zooming into the close up locations or boulders, there are individual tiles with varying resolutions that had to have been combined to keep the levels of detail as the camera is getting closer. Elkins meticulously selected the individual tiles depending on where the camera was looking to stitch together a finalized view of the model at varying vantage points. Other videos accepted by SIGGRAPH are artists’ renditions, but with the use of scientific data to create a graphical representation come some limitations. Stitching tiles together leaves some unavoidable imperfections or holes, compared to an artistic assembly. “That’s why we’re super excited that our data visualizations were pulled into the same level as some of these other pieces,” Elkins said. With the electronic theater viewing date drawing closer, Gallagher reflects on the precedent that “Tour of Asteroid Bennu” sets. “I think there’s a big demand in the public.” Gallagher said. “People love exploration, they love novelty. This is a whole new world and it’s a world that can be hard to really fully appreciate in two dimensional photographs. I think that really reflects the hunger that people have for exploration, and it’s a way to explore Bennu remotely through technology, so it’s very exciting to see it reach that level.”

Near-Earth asteroid Bennu is a rubble pile of rocks and boulders left over from the formation of the solar system. On October 20, 2020, NASA’s OSIRIS-REx spacecraft briefly touched down on Bennu and collected a sample for return to Earth. During this event the spacecraft’s arm sank far deeper into the asteroid than expected, confirming that Bennu’s surface is loosely bound. Now, scientists have used data from OSIRIS-REx to revisit the sample-collection event and better understand how Bennu’s loose upper layers are held together.