After a seven-year quest, NASA’s OSIRIS-REx mission expected to deliver Bennu asteroid samples to Earth

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Like a celestial courier on an express run, NASA’s OSIRIS-REx spacecraft is speeding toward Earth and is less than 48 hours from delivering a precious cargo of extraterrestrial material.

Stowed on board is a cache of gravel and dust from the asteroid Bennu. The spacecraft snatched up the material three years ago after delicately positioning itself just above the asteroid’s boulder-strewn surface and blasting it with a puff of nitrogen gas to raise a small cloud of interplanetary debris.

Now, after a seven-year mission, comes one final moment of jeopardy as OSIRIS-REx prepares to jettison a sample return capsule and send it on a high-speed descent through the atmosphere. If all goes well, the capsule’s journey home will end with a soft landing in the Utah desert.

“We’ve waited a really long time and now those samples are only two days away,” said Lori Glaze, director of NASA’s planetary science division, during a briefing with reporters on Friday.

At the briefing, flight engineers also said the spacecraft was performing extremely well and that it was unlikely that they would need to delay the sample’s arrival for two years when they make a final decision early Sunday about releasing the capsule.

Such a contingency would serve as a fallback option in case of issues with the direction of the spacecraft and the ability of the capsule to reach its target landing site at the Utah Test and Training Range. The remote military facility was chosen by NASA in part because it is surrounded by the largest swath of restricted air space in the United States.

Capsule’s return to Earth

The SRC separates from the main spacecraft four hours before arrival. Protected by its heat shield it enters the atmosphere at high speed, then deploys parachutes to slow its descent to a site in Utah. The SRC will then be transported by helicopter to a nearby clean room, and the canister sent to NASA’s Johnson Space Center in Houston, Tex.

SRC hits

atmosphere

at 45,000 km/h

Drogue

chute

released

Main chute deploys at 1,500 m above surface

Drogue chute

deploys at 31,000 m

above the surface

Estimated speed at touchdown 17 km/h

ivan semeniuk and john sopinski/the globe and mail, Sources:

graphic news; NASA Goddard Space Flight Center; University of

Arizona; afp

OSIRIS-REx: Return from Bennu

After a seven-year journey, NASA’s OSIRIS-REx mission is returning to Earth with a sample of a small asteroid called Bennu. Canada’s partnership in the mission means that a portion of the sample will be examined in Canadian labs for clues

to the nature of asteroids and the early history of our solar system.

Mission Timeline:

Launched: Sept. 7, 2016

Arrived at Bennu: Dec. 3, 2018

Collected Sample: Oct. 20, 2020

Departed for Earth: May 10, 2021

Capsule reaches Earth: Sept. 24, 2023

OSIRIS REx: (Origins, Spectral Interp-

retation, Resource Identification,

Security-Regolith Explorer)

Size: 3.15 m

Mass: 880 kg

Bennu asteroid

OSIRIS-REx

Sun

Earth

Solar

array

Heat

shield

Sample head:

Captured asteroid

material during five-

second contact.

Estimated sample

size: About

250 grams

TAGSAM:

Two-metre long

Touch-and-Go sample

arm used pressurized

nitrogen gas to kick up

loose material from the

surface of Bennu

Sample

head

Bennu

Diameter: 510 m

 

Composed of carbon-rich rock and loose rubble, Bennu is representative of material that was present in the early solar system when Earth formed.

Sample Return Capsule (SRC)

During the return voyage it

protects the sample head and

its contents in a sealed canister.

Capsule’s return to Earth

The SRC separates from the main spacecraft four hours before arrival. Protected by its heat shield it enters the atmosphere at high speed, then deploys parachutes to slow its descent to a site in Utah. The SRC will then be transported by helicopter to a nearby clean room, and the canister sent to NASA’s Johnson Space Center in Houston, Tex.

Drogue

chute

released

SRC hits

atmosphere

at 45,000 km/h

Main chute deploys at 1,500 m above surface

Drogue chute

deploys at 31,000 m

above the surface

Estimated speed at touchdown 17 km/h

ivan semeniuk and john sopinski/the globe and mail, Sources:

graphic news; NASA Goddard Space Flight Center; University of

Arizona; afp Picture: NASA

OSIRIS-REx: Return from Bennu

After a seven-year journey, NASA’s OSIRIS-REx mission is returning to Earth with

a sample of a small asteroid called Bennu. Canada’s partnership in the mission means that a portion of the sample will be examined in Canadian labs for clues

to the nature of asteroids and the early history of our solar system.

Mission Timeline:

Launched: Sept. 7, 2016

Arrived at Bennu: Dec. 3, 2018

Collected Sample: Oct. 20, 2020

Departed for Earth: May 10, 2021

Capsule reaches Earth: Sept. 24, 2023

OSIRIS REx: (Origins, Spectral Interpretation,

Resource Identification,

Security-Regolith Explorer)

Size: 3.15 m

Mass: 880 kg

Bennu asteroid

OSIRIS-REx

Sun

Earth

Solar

array

Heat

shield

Cameras,

spectrometers,

sensors

TAGSAM:

Two-metre long

Touch-and-Go sample

arm used pressurized

nitrogen gas to kick up

loose material from the

surface of Bennu

Sample head:

Captured asteroid

material during five-

second contact.

Estimated sample

size: About 250 grams

Sample

head

Bennu

Diameter: 510 m

 

Composed of carbon-rich rock and loose rubble, Bennu is representative of material that was present in the early solar system when Earth formed.

Sample Return Capsule (SRC)

During the return voyage it protects

the sample head and its contents in

a sealed canister.

Capsule’s return to Earth

The SRC separates from the main spacecraft four hours before arrival. Protected by its heat shield it enters the atmosphere at high speed, then deploys parachutes to slow its descent to a site in Utah. The SRC will then be transported by helicopter to a nearby clean room, and the canister sent to NASA’s Johnson Space Center in Houston, Tex.

Utah Test and

Training Range

Drogue

chute

released

SRC hits

atmosphere

at 45,000 km/h

Johnson Space Center

Main chute deploys at 1,500 m above surface

Drogue chute

deploys at 31,000 m

above the surface

Estimated speed at touchdown 17 km/h

ivan semeniuk and john sopinski/the globe and mail, Sources: graphic news; NASA Goddard Space

Flight Center; University of Arizona; afp Picture: NASA

“Our trajectory is spot on … and we fully expect to leave that meeting on Sunday morning with a ‘go’ decision,” said program manager Sandra Freund of Lockheed Martin.

If the decision is to proceed, then the action begins before dawn local time, when the returning OSIRIS-REx spacecraft releases the capsule at a distance of about 102,000 kilometres from Earth. It will then fire its thrusters to avoid crashing into the planet, leaving the capsule to complete the final stage of its journey alone.

The capsule will begin to feel Earth’s atmosphere at an altitude of about 130 kilometres and will quickly heat up as it tears through the increasingly dense air with an incoming speed of 12 kilometres per second. At that point the temperature on its heat shield could exceed 2,700 degrees, though the sample inside should not experience any warming.

As the capsule drops lower, it will release two parachutes in sequence to further slow its descent. According to the planned sequence of events, it will touch down shortly before 9 a.m. on the salt-crusted desert surface.

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A recovery team will then arrive by helicopter and ferry the capsule to a nearby temporary clean room where a canister containing the sample will be removed and shipped to NASA’s Johnson Space Center in Houston.

U.S. scientists and space officials are not the only ones banking on a safe return for the sample. Canada is a partner in the US$1.6-billion mission and will ultimately receive a 1/25 share of whatever the spacecraft has brought back. It marks the first time Canada will own a sample gathered directly from a celestial body to study and curate as a national asset.

“To me, it’s one of the most important days in Canadian planetary exploration history,” said Tim Haltigan, senior mission scientist with the Canadian Space Agency, who was on his way to Utah for the capsule’s arrival.

While the past 60 years have seen a remarkable number of spacecraft heading out all across the solar system, only a handful have ever brought samples back. Most of those are from the moon, starting with the rocks and soil that Apollo astronauts gathered between 1969 and 1972. The Soviet Union and more recently China have also brought back lunar samples using robot spacecraft. In two separate missions during the early 2000s, the U.S. also captured and returned solar particles and comet dust.

Open this photo in gallery:

To date, only Japan has managed to bring back asteroid samples, most notably in 2020 when the Hayabusa2 mission came back to Earth with a teaspoon-size sample from the asteroid Ryugu.

Now OSIRIS-REx is on track to bring an estimated 30 to 70 times that from an asteroid that is similar but subtly different in chemical composition. And while the NASA mission has already learned a lot during the time it orbited Bennu between 2018 and 2021, there’s no question the chance to conduct a detailed analysis of the sample would be the mission’s big scientific highlight.

“It’s the difference between looking at a piece of chocolate cake and tasting a piece of chocolate cake,” said Paul Wiegert, an astronomer at Western University in London, Ont., who is not directly involved with the mission. “It’s just so much of a richer experience.”

While asteroids are small, they are crucial to answering some big questions about the formation of the solar system since they are representative of the raw materials from which the Earth and other planets formed.

Meteorites – rocks that regularly fall from space and that are mostly fragments of broken-up asteroids – can also provide valuable information about what lies out there. But that data is limited by the heating that occurs when meteorites fall through the atmosphere and by contamination when they reach the ground. Usually, any volatile materials they contain, such as gases or water, are long gone by the time they are found.

That difference is what is expected to make the OSIRIS-REx sample particularly valuable to science, said Richard Binzel, a planetary scientist at the Massachusetts Institute of Technology and co-investigator on the mission.

“We want to get the most pristine time capsule from the very beginning of our planet and ourselves,” Dr. Binzel said.