{"id":12164,"date":"2020-10-19T22:38:04","date_gmt":"2020-10-19T14:38:04","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/after-four-year-journey-nasa-spacecraft-ready-to-touch-an-asteroid\/"},"modified":"2020-10-19T22:38:04","modified_gmt":"2020-10-19T14:38:04","slug":"after-four-year-journey-nasa-spacecraft-ready-to-touch-an-asteroid","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/after-four-year-journey-nasa-spacecraft-ready-to-touch-an-asteroid\/","title":{"rendered":"After four-year journey, NASA spacecraft ready to touch an asteroid"},"content":{"rendered":"

EDITOR\u2019S NOTE: <\/strong>All times are \u201cEarth Received Time\u201d when confirmation of events arrive on Earth. The events will occur more than 18 minutes earlier in real time on-board the spacecraft.<\/p>\n

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Artist\u2019s concept of the OSIRIS-REx spacecraft approaching asteroid Bennu. Credit: NASA\/Goddard\/University of Arizona<\/figcaption><\/figure>\n

Flying on autopilot more than 200 million miles from Earth, NASA\u2019s OSIRIS-REx spacecraft is on track for a daring touch and go landing on an asteroid Tuesday to grab a sample for return to scientists eager to scan the specimens for clues about the history of the solar system.<\/p>\n

The $1 billion mission\u2019s success will come down to a handful of seconds at 6:12 p.m. EDT (2212 GMT) Tuesday, when an arm extended from the OSIRIS-REx spacecraft will contact the gravely surface of asteroid Bennu, release a canister of high-pressure nitrogen gas, and attempt to capture some of the asteroid\u2019s carbon-rich soil.<\/p>\n

\u201cDue to the low gravity, we can\u2019t actually land on the surface of Bennu,\u201d said Beth Buck, OSIRIS-REx mission operations program manager at Lockheed Martin, which built and operates the spacecraft for NASA. \u201cSo we\u2019ll only be kissing the surface with a short touch and go measured in just seconds.\u201d<\/p>\n

If it works, the robotic mission will depart Bennu next year and head back to Earth, where OSIRIS-REx will deploy a re-entry module to plunge into the atmosphere and parachute to a remote U.S. military test range in Utah on Sept. 24, 2023.<\/p>\n

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer is NASA\u2019s first round-trip mission to an asteroid. The space agency selected the mission for development in 2011, and OSIRIS-REx departed Earth on Sept. 8, 2016, with a successful launch from Cape Canaveral aboard a United Launch Alliance Atlas 5 rocket.<\/p>\n

The spacecraft swung by Earth in September 2017 for a gravity assist to bend its trajectory toward the orbit of Bennu, which completes one circuit of the sun every 1.2 years. OSIRIS-REx arrived at Bennu in December 2018 and entered orbit around the asteroid, kicking off a nearly two-year campaign to map the asteroid with cameras, mineral-sniffing spectrometers, and a Canadian-built laser to measure its roughness.<\/p>\n

OSIRIS-REx also searched for a suitable sampling location, and rehearsed procedures for the touch and go landing.<\/p>\n

That culminates in the craft\u2019s descent to Bennu Tuesday, and the goal is to gather at least 2.1 ounces, or 60 grams, of asteroid specimens for return to Earth.<\/p>\n

\u201cWe all want to take those samples and come home,\u201d said Thomas Zurbuchen, head of NASA\u2019s science mission directorate, in a conference call with reporters Monday.<\/p>\n

Scientists and engineers are confident that OSIRIS-REx will execute the touch and go as expected Tuesday. But the spacecraft will be on its own during the most crucial moments of the descent.<\/p>\n

Bennu and OSIRIS-REx are currently located some 207 million miles (334 million kilometers) from Earth. At that distance, it takes more than 18 minutes for radio signals traveling at light speed to make a one-way journey from mission control the spacecraft.<\/p>\n

OSIRIS-REx will fly autonomously, employing complex navigation software, terrain tracking algorithms, and programmed commands to execute maneuvers to guide itself toward a zone roughly the size of a tennis court on the surface of Bennu.<\/p>\n

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Data from NASA\u2019s OSIRIS-REx spacecraft was used to create this shape model of asteroid Bennu at 75-centimeter resolution. Credit: NASA\/Goddard\/University of Arizona<\/figcaption><\/figure>\n

Shaped like a spinning top, Bennu measures around a third of a mile (500 meters) in diameter and rotates once on its axis every 4.3 hours. Named for a bird-like ancient Egyptian deity linked with the sun, creation and rebirth, Bennu follows a path around the sun that intersects Earth\u2019s orbit, and the asteroid makes a relatively close approach to Earth once every six years.<\/p>\n

That makes Bennu a potentially hazardous asteroid, and it poses a low threat of eventually hitting Earth. There is a 1-in-2,700 chance of Bennu impacting Earth in the late 2100s.<\/p>\n

Bennu was discovered in 1999 by a survey with a ground-based telescope searching for near-Earth asteroids. OSIRIS-REx is the first mission to visit Bennu.<\/p>\n

Since arriving at Bennu nearly two years ago, OSIRIS-REx has determined the asteroid is shedding material into space. The mission has also found that Bennu \u2014 known as a B-type asteroid \u2014 is covered in carbon-rich, water-bearing minerals. The organic material may contain carbon in a form often found in biology or in compounds associated with biology, scientists announced Oct. 8.<\/p>\n

\u201cThe abundance of carbon-bearing material is a major scientific triumph for the mission,\u201d said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. \u201cWe are now optimistic that we will collect and return a sample with organic material \u2014 a central goal of the OSIRIS-REx mission.\u201d<\/p>\n

In a press release accompanying the announcement of the new scientific data earlier this month, NASA described Bennu as a \u201cdiamond-shaped pile of rubble floating in space.\u201d<\/p>\n

Scientists also said OSIRIS-REx\u2019s targeted touchdown site \u2014 dubbed \u201cNightingale\u201d \u2014 also harbors the signature of organic materials, the building blocks of life. The Nightingale location on Bennu\u2019s northern hemisphere is situated inside inside a 460-foot (140-meter) crater, but the area deemed safe for the spacecraft to touch is 52 feet (16 meters) across.<\/p>\n

The spacecraft\u2019s solar panels extend more than 20 feet, or 6.2 meters, tip-to-tip.<\/p>\n

\u201cIt\u2019s kind of a tight fit,\u201d Lauretta said earlier this year.<\/p>\n

But scientists expect Nightingale to provide a rich return. Observations from OSIRIS-REx also indicate the material at the touch and go was only recently exposed to the harsh environment of space, meaning the mission could snag pristine samples that have been undisturbed for most of the solar system\u2019s 4.5 billion-year history.<\/p>\n

But Bennu offered up some surprises that forced mission managers to replan how OSIRIS-REx will navigate its way to the sampling site.<\/p>\n

Bennu turned out to be more rugged than mission planners expected, with large boulders and a lack of expanses with smooth, fine-grained soils that would be perfect for OSIRIS-REx to try and reach during the sampling run.<\/p>\n

After seeing Bennu up close, engineers developed upgraded navigation capabilities to help guide OSIRIS-REx the final phase of the descent to the rugged asteroid.<\/p>\n

The spacecraft will use a capability called natural feature tracking to take a series of images with a navigation camera to autonomously identify rocks, craters and other landmarks on the asteroid\u2019s surface, yielding data on position and relative velocity. OSIRIS-REx will autonomously will compare the imagery with a topographic map loaded into the computer before the descent.<\/p>\n

If the spacecraft detects it is approaching a dangerous area, it can command an abort and back away from Bennu as late as when it is 16 feet, or 5 meters, from the asteroid\u2019s surface. If all goes according to plan, the navigation algorithms will steer OSIRIS-REx to a touch and go site with an accuracy of 23 feet, or 7 meters, three times better than originally planned.<\/p>\n

The natural feature tracking algorithms were successfully tested during a rehearsal Aug. 11 that took the spacecraft as close as 131 feet, or 40 meters, from Bennu.  The spacecraft\u2019s cameras captured higher-resolution views of the Nightingale sampling location when OSIRIS-REx was flying directly over the site in August, allowing ground teams to update and refine the maps for the natural feature tracking capability before the real sampling attempt.<\/p>\n

The August rehearsal followed a similar practice run April 15 that simulated OSIRIS-REx\u2019s decent down to an altitude 213 feet, or 65 meters, before the craft backed away from Bennu.<\/p>\n

Officials originally aimed to attempt the sample collection in August, but managers pushed back the event to October to allow more time for teams to complete preparations while contending with remote work and physical distancing requirements to slow the spread of COVID-19.<\/p>\n