Illustration of NASA’s
OSIRIS-REx spacecraft during a burn of its main engine for arrival at target
Asteroid Bennu in Dec. 2018. Credit: University
FL – NASA’s OSIRIS-REx asteroid sampling spacecraft successfully
completed the first in a series of critical main engine firings in early
October that significantly slowed the probes speed and put it on course for
final approach to target Bennu this December.
A second firing is on tap just days away for Oct. 15.
commanded OSIRIS-Rex to carry out the firing known as the first Asteroid
Approach Maneuver (AAM-1) on Oct. 1. All
appeared to go well but the team need to gather additional and analyze
additional telemetry and tracking to confirm a positive outcome.
“New tracking data confirm that the spacecraft
completed its first Asteroid Approach Maneuver (AAM-1) on Oct. 1, starting the
final approach to Bennu,” officials reported yesterday, Oct. 8.
engine burn slowed the spacecraft as planned – by a speed of 785.831 miles per
hour (351.298 meters per second) and consumed 532.4 pounds (241.5 kilograms) of
The braking maneuver slowed
the spacecraft’s speed relative to Bennu from approximately 1,100 mph (491
m/sec) to 313 mph (140 m/sec).
Three more AAMs are scheduled over the next two
months “as the spacecraft prepares to match Bennu’s speed so it can safely
navigate around the asteroid.”
The second maneuver known as AAM-2 is slated
for early next week on Oct. 15.
As of today with 53 days left until arrival at
Benuu, OSIRIS-Rex is now less
than 80,500 km (50,300 miles) distant.
OSIRIS-Rex, which stands for the Origins, Spectral Interpretation, Resource
Identification, Security-Regolith Explorer, has journeyed approximately 1.1
billion miles (1.88 billion km) since its Sept. 8, 2016, launch on a United
Launch Alliance Atlas V rocket.
The one way light time for signals is currently
OSIRIS-Rex counts as NASA’s first
mission to visit a near-Earth asteroid, survey the surface, collect a sample
and deliver it safely back to Earth.
It is scheduled to arrive at Bennu in about two months on
Dec. 3, 2018.
The probe has begun science operations and is
taking images with the cameras to support navigation and science objectives.
Watch this GIF of Bennu
OSIRIS-REx Approaches. This
processed and cropped set of images shows Bennu (in the center of the frame)
from the perspective of the OSIRIS-REx spacecraft as it approaches the
asteroid. During the period between August 17 and October 1, 2018 the
spacecraft’s PolyCam imager obtained this series of 20 four-second exposures
every Monday, Wednesday, and Friday as part of the mission’s optical navigation
campaign. From the first to the last
image, the spacecraft’s range to Bennu decreased from 2.2 million km to 192,000
km, and Bennu brightened from approximately magnitude 13 to magnitude 8.8 from
the spacecraft’s perspective. Credit: NASA/Goddard/University of Arizona
“From the beginning
of the mission’s science operations on Aug. 17 through AAM-1, PolyCam obtained
optical navigation images (OpNavs) of Bennu on a Monday, Wednesday and Friday
cadence. After AAM-1, PolyCam is taking daily OpNavs as the spacecraft
continues to close in on the asteroid,” NASA reported Oct. 8.
“This last week the spacecraft’s MapCam camera also began taking
daily Phase Function images. These images support the mission’s science
requirement to measure changes in light reflected from Bennu’s surface as the
Sun illuminates the asteroid across a range of angles. These observations
provide information on Bennu’s albedo and the way light reflects under various
Nov. 12 and target OSIRIS-Rex for arrival
on Dec. 3.
to arrive at a position 12 miles (20 km) from Bennu on Dec. 3. After arrival,
the spacecraft will initiate asteroid proximity operations by performing a
series of fly-bys over Bennu’s poles and equator.”
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