NASA’s OSIRIS-REx mission arrived at Bennu back in 2018. A major event planned for August and keeping scientists eager to see the results. You might not have heard much about this mission, so let me bring you up to date with some important details.
OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer. The mission, survey and collect samples from the asteroid Bennu.
The Trip to Bennu
On 8 September 2016 at 23:05 UTC, OSIRIS-REx launched aboard a United Launch Alliance Atlas V 411 from Cape Canaveral Space Launch Complex 41. This configuration of the Atlas rocket consisted of an RD-180 powered the first stage with a single AJ-60A solid-fuel booster and a Centaur upper stage. OSIRIS-REx separated from the upper stage of the launch vehicle 55 minutes after ignition. The launch went according to plan, with no anomalies worked before or during launch.
The OSIRIS-REx spacecraft traveled 1.2 billion miles (2 billion kilometers) to arrive at the Bennu asteroid. The spacecraft placed itself into an orbit of Bennu to start collecting data about the asteroid.
Prior to arriving, OSIRIS-REx took the opportunity to search for near-Earth objects. The OSIRIS-REx team used the spacecraft’s MapCam camera to search for Trojan asteroids and took about 135 survey images each day for processing by scientists at the University of Arizona. Even though no new Trojans were found, the activity acted as a good dress rehearsal for the approach to Bennu. The spacecraft searched for natural satellites and other potential hazards on the approach to Bennu.
Early data collection
The spacecraft commenced flyovers of Bennu’s North Pole, equatorial region, and the South Pole. The data collected allowed for the generation of precise maps of Bennu. The maps and data allow the mission team to determine accurate estimates of Bennu’s mass and the spin rate which comes in handy for determining the best sample collection site.
A crucial aspect for the next stage of the mission includes using the high-resolution maps. Potential sample collection sites were evaluated against the collected data. The spacecraft approached closer and closer to the asteroid for a better evaluation of the collection sites.
Preliminary spectroscopic surveys of the asteroid’s surface detected the presence of hydrated minerals believed to be in the form of clay. Researchers suspect the hydroxyl groups originated from water presence in its parent body before Bennu split off.
“The presence of hydrated minerals across the asteroid confirms that Bennu, a remnant from early in the formation of the solar system, is an excellent specimen for the OSIRIS-REx mission to study the composition of primitive volatiles and organics. When samples of this material are returned by the mission to Earth in 2023, scientists will receive a treasure trove of new information about the history and evolution of our solar system.”
Amy Simon, OVIRS deputy instrument scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
There is a snag
In February 2020, NASA’s OSIRIS-REx spacecraft executed a 0.4-mile (620-m) flyover of the backup sample collection site. Preliminary telemetry indicated the OSIRIS-REx Laser Altimeter (OLA) did not operate correctly during the flyover. The OLA provides ranging data to the spacecraft’s PolyCam imager. The ranging data allow the camera to focus while imaging the area around the sample collection site. Consequently, the OLA performance degradation resulted in out of focus flyover images. Everything else about the spacecraft appears to be nominal.
OLA previously completed all of its principal requirements for the OSIRIS-REx mission. OLA’s scans of Bennu’s surface helped to create high-resolution 3D global maps of Bennu’s topography that were crucial for selecting the primary and backup sample collection sites last fall.
In August, a robotic spacecraft will make NASA’s first-ever attempt to descend to the surface of an asteroid, collect a sample, and ultimately bring it safely back to Earth. To achieve this challenging feat, the OSIRIS-REx mission team devised new techniques to operate in asteroid Bennu’s environment.
Trial run
On Apr. 14, the mission “Checkpoint” rehearsal will pursue its first sample practice run. The OSIRIS-REx which will also place the spacecraft the closest it’s ever been to Bennu. This rehearsal is a chance for the OSIRIS-REx team and spacecraft to test the first steps of the robotic sample collection event.
During the full touchdown sequence, the spacecraft uses a sequence of three separate thruster firings to gradually approach the asteroid’s surface. The spacecraft will check out critical systems to ensure that everything works as expected before the actual sample collection.
Following the Checkpoint rehearsal, the team will verify the flight system’s performance during the descent, and that the Checkpoint burns accurately adjusted the descent trajectory for the subsequent Matchpoint burn.
The craft is not the only thing far from mission control. The team has maximized the use of remote work over the last month of preparations for the checkpoint rehearsal. As part of the COVID-19 response, limited personnel will command the spacecraft from Lockheed Martin Space’s facility. The rest of the team works remotely.
The mission is scheduled to perform a second rehearsal on Jun. 23, taking the spacecraft down to an approximate altitude of 82 ft (25 m). OSIRIS-REx’s first sample collection attempt is scheduled for Aug. 25.
Here are some interesting links about the program:
https://www.nasa.gov/osiris-rex
About The Author
Bill D’Zio
Co-Founder at WestEastSpace.com
Bill founded WestEastSpace.com after returning to China in 2019 to be supportive of his wife’s career. Moving to China meant leaving the US rocket/launch industry behind, as the USA and China don’t see eye to eye on cooperation in space. Bill has an engineering degree and is an experienced leader of international cross-functional teams with experience in evaluating, optimizing and awarding sub-contracts for complex systems. Bill has worked with ASME Components, Instrumentation and Controls (I&C) for use in launch vehicles, satellites, aerospace nuclear, and industrial applications.
Bill provides consulting services for engineering, supply chain, and project management.
