OSIRIS scrapes asteroid surface
An astounding feat of science and engineering has occurred in space this week, with a NASA robot grabbing a sample of an asteroid.
NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) spacecraft has unfurled its robotic arm, and in a first for the agency, briefly touched an asteroid to collect dust and pebbles from the surface for delivery to Earth in 2023.
The well-preserved, ancient asteroid, known as Bennu, is currently more than 321 million kilometres from Earth.
Bennu offers scientists a window into the early solar system as it was first taking shape billions of years ago and flinging ingredients that could have helped seed life on Earth.
If Tuesday’s sample collection event, known as ‘Touch-And-Go’ (TAG), provided enough of a sample, mission teams will command the spacecraft to begin stowing the precious primordial cargo to begin its journey back to Earth in March 2021. Otherwise, they will prepare for another attempt in January.
“This amazing first for NASA demonstrates how an incredible team from across the country came together and persevered through incredible challenges to expand the boundaries of knowledge,” said NASA Administrator Jim Bridenstine.
“Our industry, academic, and international partners have made it possible to hold a piece of the most ancient solar system in our hands.”
At around 4:50 am, Wednesday, Sydney time, OSIRIS-REx fired its thrusters to nudge itself out of orbit around Bennu, where it has been waiting for almost two years.
It extended the shoulder, then elbow, then wrist of its 3.35-metre sampling arm, known as the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), and transited across Bennu while descending about 805 meters toward the surface.
After a four-hour descent, at an altitude of approximately 125 metres, the spacecraft executed the ‘Checkpoint’ burn, the first of two manoeuvres to allow it to precisely target the sample collection site, known as ‘Nightingale’.
Ten minutes later, the spacecraft fired its thrusters for the second ‘Matchpoint’ burn to slow its descent and match the asteroid’s rotation at the time of contact.
It then continued a treacherous, 11-minute coast past a boulder the size of a two-story building, nicknamed ‘Mount Doom’, to touch down in a clear spot in a crater on Bennu’s northern hemisphere.
The size of a small parking lot, the Nightingale site is one of the few relatively clear spots on this unexpectedly boulder-covered space rock.
“This was an incredible feat – and today we’ve advanced both science and engineering and our prospects for future missions to study these mysterious ancient storytellers of the solar system,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at the agency’s headquarters in Washington.
“A piece of primordial rock that has witnessed our solar system’s entire history may now be ready to come home for generations of scientific discovery, and we can’t wait to see what comes next.”
“After over a decade of planning, the team is overjoyed at the success of today’s sampling attempt,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson.
“Even though we have some work ahead of us to determine the outcome of the event – the successful contact, the TAGSAM gas firing, and back-away from Bennu are major accomplishments for the team. I look forward to analysing the data to determine the mass of sample collected.”
All spacecraft telemetry data indicates the TAG event executed as expected. However, it will take about a week for the OSIRIS-REx team to confirm how much sample the spacecraft collected.
Real-time data indicates the TAGSAM successfully contacted the surface and fired a burst of nitrogen gas. The gas should have stirred up dust and pebbles on Bennu’s surface, some of which should have been captured in the TAGSAM sample collection head.
OSIRIS-REx engineers also confirmed that shortly after the spacecraft made contact with the surface, it fired its thrusters and safely backed away from Bennu.
“Today’s TAG manoeuvre was historic,” said Lori Glaze, Planetary Science Division director at NASA Headquarters in Washington.
“The fact that we safely and successfully touched the surface of Bennu, in addition to all the other milestones this mission has already achieved, is a testament to the living spirit of exploration that continues to uncover the secrets of the solar system.”
Stay tuned to the OSIRIS-REx Twitter page for more exciting updates.