The 4 year mission to the asteroid Bennu culminates today as NASA's Osiris REX spacecraft takes its first crack at a 10 second sampling - to collect two ounces - of asteroid material. We understand the van-sized craft is aiming for a relatively flat, tennis-court sized area to make its brief parking and soil grab. All the more incredible as it took 1 year to find the spot, given the original assumption of sandy terrain was dashed on further inspection. (Close up photos showed the asteroid with extremely rocky landscape, lots of boulders)
Consider that the NASA space craft came from 200 miles distant - a trek lasting four years in all - to assume a half mile high orbit - and that it will take another four hours to gradually descend to make a touchdown and sampling maneuver that will last 5 - 10 seconds. That maneuver will entail the craft's 11 - foot arm being extended just long enough to shoot out pressurized nitrogen gas enabling it to extract the churned up dirt and gravel.
Programmed in advance, the spacecraft will operate autonomously during the extraction process. We will know of success or failure some 18 minutes after the craft transmits its info. That is the time lag in radio communications each way. If a failure occurs, there will be the opportunity to try again in January.
Soon after success the spacecraft will commence its long journey back to Earth, samples in tow, reaching a landing site in Utah in March, 2023. This is a momentous first which many of us (especially elder folks - including suffering with cancer like me) hope we will be around to see. This is given that while earlier NASA missions have brought back lunar rocks, solar wind particles and comet dust - no asteroid sample returns have ever been attempted. So this is a first, hence, big time space news - especially for space junkies, space scientists, planetary astronomers.
The latter are excited, because the mission promises to open our eyes to the very origins and "DNA" of the solar system. Bennu itself is grouped in the "C -class" of asteroids, or Carbonaceous class . This is because it is carbon -rich and likely formed when our solar system began 4.5 billion years ago. Hence, geologic clues found in its sample soil could tell us more about the solar system's origins, Many scientists also believe its "pristine carbon building blocks" could help explain how life formed on Earth and possibly elsewhere.
Bennu is also a "near Earth Object" or NEO - which have orbits that allow them to approach or even intersect the orbit of Earth. Indeed, ten NEOs have come closer to the Earth than the Moon since 2004. Bennu swings close to Earth every 6 years and according to NASA computations, could take direct aim at us in the next century. NASA currently puts the odds of collision at 1 in 2,700. With a diameter slightly greater than the height of the Empire State Bldg. this would create quite an explosion equal to roughly 300 megatons.
Not enough to wipe out the planet but enough to incinerate a city like New York or LA, and level an island like Barbados. Fortunately, most of us won't be around at that future date to worry - and we simply look forward now to the arrival of a few ounces of Bennu by 2023.
No comments:
Post a Comment