NASA Drops Spacecraft Into Orbit Around Potentially Hazardous Asteroid Bennu (cnet.com)

NASA's asteroid-chasing Osiris-Rex spacecraft has been placed in an orbit around Bennu, an asteroid that drifts through the solar system's asteroid belt between Earth and Mars. "By inserting itself into orbit around Bennu, Osiris-Rex will survey the asteroid from a distance of only about 1 mile (1.75 kilometers) from its center," reports CNET. "Bennu's small size creates an incredibly tiny gravitational force, so maintaining that orbit will require lots of little adjustments, made by NASA and its collaborating organizations." From the report: "The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu's surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force," said Dan Wibben, maneuver and trajectory design lead. NASA also released a GIF of the various surveys Osiris-Rex carried out after arriving at Bennu in early December The series of images, captured between Nov. 30 and Dec. 31, helped the team more accurately determine Bennu's mass, which ensured that the orbital insertion would proceed smoothly.

The orbital period, lasting until mid-February, is expected to provide additional details about Bennu's gravity, orientation and spin, along with a better understanding of its mass. All those observations should lead to completing one of the chief objectives for Osiris-Rex: retrieve a sample from Bennu's surface and fly it back to Earth. In 2020, the spacecraft will extend a specially designed arm, called Tagsam, for a brief high-five with the asteroid. The arm will blow nitrogen gas onto the surface of Bennu, kicking up handfuls of dirt, which the spacecraft will fly back to Earth in 2023.

Comments

Re: Journalism 101

[angel'o'sphere]

Most of Europe never used any imperial system/unit anyway. Unless you want to call "having a foot or a mile" imperial. Every foot, mile, every "elbow" every "thumb" as in inch, every pound or ounce had its own size, and no, the correlation between one and the other was not based on 12 or 16, but was most of the time random. While weights usually stayed constant over time, that means a pound was a pound was a pound, distances did not. When the old "king" died, the new one changed feet and thumb and elbow according to his own body size. Miles were arbitrary set, sometimes rulers thought the longer the better (going far away from the roman 1000 paces metric - a pace are two steps, for you americans you mix up paces with steps). It was a kind of prestige object, because they converted how many miles a soldier could work in an hour (about 3) back and force into how fast their fastest elite troops were. So if they managed to do 1800 paces in one hour the mile would be as long as that ... often that number was simply invented. Other tricks were, to simply use two hours of walking instead of one, so became the "Baadische Meile" the longest mile in german history (Mile of the Margraviate of Baaden) https://en.wikipedia.org/wiki/.... Albeit in this case they did not cheat, besides using 2h as base and interestingly the Margrave Carl Friedrich himself with his entourage walked in 2h the distance of 8.88889 km

Germany probably topped it by having about 50 different definitions for everything.

Anyway, the slow unification and the introduction of railways etc. forced them to unify the systems, it is a bit complicate to plan a railway trip from Warschau to Madrid if you have to go through dozens of borders where each principal has defined his one system of length and his own local time zone.

Re: Journalism 101

[pslytely psycho]

Ah, the coming of the railroad. The railroads are also responsible for the time zones.

"American railroads maintained many different time zones during the late 1800s. Each train station set its own clock making it difficult to coordinate train schedules and confusing passengers. Time calculation became a serious problem for people traveling by train (sometimes hundreds of miles in a day), according to the Library of Congress. Every city in the United States used a different time standard, so there were more than 300 local sun-times to choose from. Railroad managers tried to address the problem by establishing 100 railroad time zones, but this was only a partial solution to the problem.

Operators of the new railroad lines needed a new time plan that would offer a uniform train schedule for departures and arrivals. Four standard time zones for the continental United States were introduced on November 18, 1883."