Author Topic: LIVE: ULA Atlas V - OSIRIS-REx - Sept 8, 2016 (Asteroid Sample Return)  (Read 79912 times)

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Searching for Earth's Trojan Asteroids

OSIRIS-REx Mission

Published on Feb 9, 2017
Trojans asteroids are travel companions to planets system as they orbit the sun, remaining near a stable point 60 degrees in front of or behind the planet. Only one Earth-Trojan asteroid is known (2010 TK7), but scientists believe there could be more.

In mid-February 2017, NASA's OSIRS-REx mission will search for these elusive objects when the spacecraft passes by Earth's L4 Lagrange point, en route to asteroid Bennu in 2018.

Video Credit: NASA's Goddard Space Flight Center/Dan Gallagher
Orbital Graphics: University of Arizona/Heather Roper

https://www.youtube.com/watch?v=pYqEUGEZUnk?t=001

Tony De La Rosa

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NASA’s OSIRIS-REx spacecraft, now on a two year outbound journey to the near-Earth asteroid Bennu, is a good deal closer to home than you might think. At play is a gravity assist maneuver that will take the craft past the Earth on September 22nd, propelling OSIRIS-REx into the orbital plane of its target. As of August 25th, the spacecraft was 16.6 million kilometers from the Earth.

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The OSIRIS-REx team is reporting that a course adjustment burn was performed on August 23rd, a successful correction that marked the first time the spacecraft’s attitude control system (ACS) had been used in what is being called a ‘turn-burn-turn’ sequence. It’s a precision maneuver requiring the momentum wheels on OSIRIS-REx to turn the spacecraft so its thrusters are lined up for the burn. When the burn is complete, the momentum wheels turn the spacecraft back to its previous orientation. Thrust is monitored by an on-board accelerometer.

The maneuver on August 23rd lasted a scant 77 seconds, successfully changing the velocity of the spacecraft by 47.9 centimeters per second while using 0.46 kilogram of fuel. Precision work indeed, but just a warm-up for what will be needed at the asteroid, whose gravitational field is so weak that the smallest changes in velocity will allow exploration and mapping.

https://www.centauri-dreams.org/?p=38368

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https://www.asteroidmission.org/?latest-news=nasas-asteroid-bound-spacecraft-slingshot-past-earth


August 31, 2017 -

NASA’s asteroid sample return mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer), will pass about 10,000 miles (16,000 kilometers) above Earth just before 12:52 p.m. EDT on Friday, Sept. 22. Using Earth as a slingshot, the spacecraft will receive an assist to complete its journey to the asteroid Bennu.

This artist’s concept shows the OSIRIS-REx spacecraft passing by Earth.
Credits: NASA’s Goddard Space Flight Center/University of Arizona

OSIRIS-REx is undertaking a challenging mission to visit the near-Earth asteroid, survey the surface, collect samples and deliver them safely back to Earth. This is the first NASA mission to attempt such an undertaking. The spacecraft is halfway through its two-year outbound journey, and now OSIRIS-REx needs an extra boost to successfully rendezvous with Bennu.

Bennu’s orbit around the Sun is tilted six degrees in comparison to Earth’s. The gravity assist will change OSIRIS-REx’s trajectory to put the spacecraft on a course to match the asteroid’s path and speed.

“The Earth Gravity Assist is a clever way to move the spacecraft onto Bennu’s orbital plane using Earth’s own gravity instead of expending fuel,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson.

The team has already made multiple adjustments to the spacecraft’s path since launch on Sept. 8, 2016. The largest was a deep space maneuver on Dec. 28, 2016, that changed the speed and path of the spacecraft to target Earth for the flyby. There have also been three trajectory correction maneuvers – one on Oct. 7, 2016, one on Jan. 18, 2017, and another on Aug. 23, 2017 (30 days before the gravity assist) – that further refined the spacecraft’s trajectory in preparation for the flyby.

The navigation team comprises employees from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and KinetX Aerospace. KinetX Aerospace navigation team members plan and carry out all OSIRIS-REx maneuvers with the Lockheed Martin spacecraft operations team at the Lockheed Martin Waterton Campus in Littleton, Colorado. To properly target the Earth Gravity Assist, the navigation team calculates any required amount of change in the spacecraft’s course and speed. This information is then translated by the operations team into commands that are uploaded to the spacecraft and executed by firing the spacecraft’s rocket engines.

After traveling almost 600 million miles, OSIRIS-REx will approach Earth at a speed of about 19,000 mph. The spacecraft will fly over Australia before reaching its closest point to Earth over Antarctica, just south of Cape Horn, Chile.

“For about an hour, NASA will be out of contact with the spacecraft as it passes over Antarctica,” said Mike Moreau, the flight dynamics system lead at Goddard. “OSIRIS-REx uses the Deep Space Network to communicate with Earth, and the spacecraft will be too low relative to the southern horizon to be in view with either the Deep Space tracking station at Canberra, Australia, or Goldstone, California.”

NASA will regain communication with OSIRIS-REx at 1:40 p.m. EDT, roughly 50 minutes after closest approach.

At 4:52 p.m. EDT, four hours after closest approach, OSIRIS-REx will begin science observations of Earth and the Moon to calibrate its instruments.

During the gravity assist, OSIRIS-REx will pass through a region of space that is inhabited by Earth-orbiting satellites, and NASA has taken precautions to ensure the safety of the spacecraft as it flies through this area. The mission’s flight dynamics team designed a small maneuver that, if necessary, could be executed a day before closest approach to change the spacecraft’s trajectory slightly to avoid a potential collision between OSIRIS-REx and a satellite.

“A few weeks after the flyby we will assess the outgoing trajectory on its way to Bennu,” said Dan Wibben, the maneuver design and trajectory analysis lead from KinetX Aerospace. “There is a maneuver planned in case we need to adjust the orbit just a little bit to push the spacecraft back on track.”

In late June of 2018, the team will perform another deep space maneuver to further target the rendezvous with Bennu. Then beginning in October 2018, a series of asteroid approach maneuvers will be executed to slow the spacecraft with respect to the asteroid.

Once OSIRIS-REx rendezvous with Bennu in late 2018, the spacecraft will begin surveying the surface.

“The asteroid’s small size and low gravity makes OSIRIS-REx the most challenging mission that I have worked on,” said Peter Antreasian, the navigation team chief from KinetX Aerospace. “At roughly 500 meters in diameter, Bennu will be the smallest object that NASA has orbited.”

While the engineering team is busy carrying out the Earth Gravity Assist, the mission invites members of the public to mark the occasion by participating in the Wave to OSIRIS-REx social media campaign. Individuals and groups from anywhere in the world are encouraged to take photos of themselves waving to OSIRIS-REx, share them using the hashtag #HelloOSIRISREx and tag the mission account in their posts on Twitter (@OSIRISREx) or Instagram (@OSIRIS_REx).

Participants may begin taking and sharing photos at any time—or wait until the OSIRIS-REx spacecraft makes its closest approach to Earth at 12:52p.m. EDT on Friday, Sept. 22.

NASA’s Goddard Space Flight Center provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space Systems in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for its Science Mission Directorate in Washington.
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https://www.nasa.gov/image-feature/goddard/2017/large-binocular-telescope-snags-first-glimpse-of-osiris-rex

This set of magnified, cropped images shows NASA’s OSIRIS-REx spacecraft (highlighted in red) as it approaches Earth for its Sept. 22 Earth Gravity Assist. To improve visibility, the images have been inverted so that black and white are reversed. The images were taken Sept. 2, by the Large Binocular Telescope Observatory located on Mount Graham in Arizona. This is the first Earth-based view of the spacecraft since its launch on Sept. 8, 2016.

OSIRIS-REx, which was approximately 7 million miles (12 million kilometers) away when the images were taken, appears at approximately 25th magnitude.

The Large Binocular Telescope is a pair of 8.4-meter mirrors mounted side by side on the same mount, that can work together to provide resolution equivalent to a 22.7-meter telescope. The telescope typically conducts imaging of more distant objects but took this opportunity to look for OSIRIS-REx with a pair of wide-field cameras (one per mirror) as the spacecraft approaches Earth for its gravity assist. This encounter will change the spacecraft’s trajectory and set it on course to rendezvous with asteroid Bennu, where it will collect a sample of surface material and return it to Earth for study in 2023. The Large Binocular Telescope Observatory is headquartered on the Tucson campus of the University of Arizona.

The OSIRIS-REx mission team is collecting other images of the spacecraft taken by observatories and other ground-based telescopes around the world during this period – approximately Sept. 10-23, depending on location and local conditions. Individuals and groups may submit images of the spacecraft via the mission’s website, where instructions to locate the spacecraft in the sky are also available.

For more information on the OSIRIS-REx mission, visit:

www.nasa.gov/osirisrex  and www.asteroidmission.org

For more information on the Large Binocular Telescope, visit:

www.lbto.org
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OSIRIS-REx Earth Gravity Assist (EGA) Observation Campaign

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Observatories and astronomers with their own equipment are invited to take images of OSIRIS-REx as it approaches and retreats from its closest position over Earth − approximately 11,000 miles (17,000 km) above the planet’s surface.
The mission will collect images of OSIRIS-REx taken by Earth-based observers around the world during this period – approximately Sept. 10-23, depending on location and local conditions. See below for more details about when and where you can observe the spacecraft and how to submit your images.
« Last Edit: 09/21/2017 05:29 AM by zubenelgenubi »
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Online catdlr

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ScienceCasts: Riding the Slingshot to Bennu

ScienceAtNASA
Published on Sep 21, 2017

Visit http://science.nasa.gov/ for more.

Gravity’s pull is being used to help propel a small spacecraft known as OSIRIS-REx to a near-Earth asteroid called Bennu.

OSIRIS-REx Mission: http://www.asteroidmission.org/

https://www.youtube.com/watch?v=B5suKnZxCpI?t=001

Tony De La Rosa

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Sept. 22, 2017

NASA’S OSIRIS-REx Spacecraft Slingshots Past Earth
NASA’s asteroid sample return spacecraft successfully used Earth’s gravity on Friday to slingshot itself on a path toward the asteroid Bennu, for a rendezvous next August.

At 12:52 p.m. EDT on Sept. 22, the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) spacecraft came within 10,711 miles (17,237 km) of Antarctica, just south of Cape Horn, Chile, before following a route north over the Pacific Ocean.

OSIRIS-REx launched from Cape Canaveral Air Force Station in Florida on Sept. 8, 2016, on an Atlas V 411 rocket. Although the rocket provided the spacecraft with the all the momentum required to propel it forward to Bennu, OSIRIS-REx needed an extra boost from the Earth’s gravity to change its orbital plane. Bennu’s orbit around the Sun is tilted six degrees from Earth’s orbit, and this maneuver changed the spacecraft’s direction to put it on the path toward Bennu.

As a result of the flyby, the velocity change to the spacecraft was 8,451 miles per hour (3.778 kilometers per second).

“The encounter with Earth is fundamental to our rendezvous with Bennu,” said Rich Burns, OSIRIS-REx project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “The total velocity change from Earth’s gravity far exceeds the total fuel load of the OSIRIS-REx propulsion system, so we are really leveraging our Earth flyby to make a massive change to the OSIRIS-REx trajectory, specifically changing the tilt of the orbit to match Bennu.”

The mission team also is using OSIRIS-REx’s Earth flyby as an opportunity to test and calibrate the spacecraft’s instrument suite. Approximately four hours after the point of closest approach, and on three subsequent days over the next two weeks, the spacecraft’s instruments will be turned on to scan Earth and the Moon. These data will be used to calibrate the spacecraft’s science instruments in preparation for OSIRIS-REx’s arrival at Bennu in late 2018. 

“The opportunity to collect science data over the next two weeks provides the OSIRIS-REx mission team with an excellent opportunity to practice for operations at Bennu,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “During the Earth flyby, the science and operations teams are co-located, performing daily activities together as they will during the asteroid encounter.”

The OSIRIS-REx spacecraft is currently on a seven-year journey to rendezvous with, study, and return a sample of Bennu to Earth. This sample of a primitive asteroid will help scientists understand the formation of our solar system more than 4.5 billion years ago.

NASA’s Goddard Space Flight Center provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space Systems in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for the Science Mission Directorate in Washington.

https://www.nasa.gov/feature/goddard/2017/osiris-rex-spacecraft-slingshots-past-earth

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https://www.nasa.gov/image-feature/goddard/2017/osiris-rex-views-the-earth-during-flyby



A color composite image of Earth taken on Sept. 22 by the MapCam camera on NASA’s OSIRIS-REx spacecraft. This image was taken just hours after the spacecraft completed its Earth Gravity Assist at a range of approximately 106,000 miles (170,000 kilometers). MapCam is part of the OSIRIS-REx Camera Suite (OCAMS) operated by the University of Arizona. Visible in this image are the Pacific Ocean and several familiar landmasses, including Australia in the lower left, and Baja California and the southwestern United States in the upper right. The dark vertical streaks at the top of the image are caused by short exposure times (less than three milliseconds). Short exposure times are required for imaging an object as bright as Earth, but are not anticipated for an object as dark as the asteroid Bennu, which the camera was designed to image.

For more images from NASA’s OSIRIS-REx spacecraft, visit:
http://www.asteroidmission.org/galleries/#spacecraft-imagery

Credit: NASA's Goddard Space Flight Center/University of Arizona
Last Updated: Sept. 26, 2017
Editor: Karl Hille
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