NASA has redirected its OSIRIS-REx spacecraft from its recent mission to asteroid Bennu to study another celestial body, the Apophis, in what is essentially an ‘asteroid hopping’ mission. Even more interestingly, the new asteroid is going to make one of the closest passes from Earth five years from now.
After successfully orbiting Bennu and following the mission change – a decision taken after the discovery of excess fuel – NASA has also renamed the space probe as OSIRIS-APEx. The Bennu mission was seven years and a 4-billion-mile journey, and the new mission will last an equal duration.
Scientists have long clarified that Apophis poses no danger to Earth in terms of a collision course. However, exploring celestial bodies still goes a long way in unraveling the mysteries behind the origins of the solar system billions of years ago, the formation of planets, and possibly deeper insights into the evolution of the universe itself. The EurAsian Times had previously touched upon this domain of physics and astronomical sciences.
Series Of Sample Return Missions
OSIRIS’s new mission, however, comes after a series of other successful man-made spacecraft that were sent to explore other celestial bodies, including the European Space Agency (ESA) Rosetta probe and the Japanese Space Exploration Agency’s (JAXA) Hayabusa spacecraft.
Rosetta landed on the Philae comet on November 12, 201, ten years after it was launched on March 2, 2004. Hayabusa, meanwhile, not only landed on the Itokawa asteroid in November 2005 but also returned samples from the space rock to Earth on June 13, 2010, making it a ground-breaking mission.
New Asteroid For Space Rock Lander
Apophis, named after the Egyptian god of Chaos, is anticipated to pass within a remarkably close distance of 32,000 kilometers from Earth’s surface on April 13, 2029. Closer than any recorded historical instance, it presents a unique opportunity to gather valuable data from the 370-meter (1,200-feet)-wide asteroid. The close distance will also make it visible from the Earth’s northern hemisphere to the naked eye.
OSIRIS stands for Origins, Spectral Interpretation, Resource Identification, and Security, with the new mission designation Apophis Explorer (APEx). It had just completed a seven-year mission to Bennu as the OSIRIS-REx spacecraft and returned a sample from Bennu’s surface to Earth in September. With a quarter of its fuel remaining, NASA decided to relaunch it for a rendezvous with Apophis in a $200 million mission.
What Will It Do On The New Asteroid?
The mission, however, will not involve landing on the asteroid, collecting a sample, and sending it back to Earth, as it did with Bennu (explained subsequently).
Instead, it will orbit the asteroid, come within five meters (16 feet) of the surface, and fire its thrusters to see how much dust gets blown off. “This maneuver will stir up surface rocks and dust to give scientists a peek at the material below,” said a NASA’s Goddard Space Flight Center statement.
“The spacecraft will conduct many of the same investigations OSIRIS-REx did at Bennu, including using its instrument suite of imagers, spectrometers, and a laser altimeter to map the surface and analyze its chemical makeup closely,” the statement added.
The OSIRIS-APEx’s mission will continue near the asteroid for 18 months after it has passed Earth. This extended mission duration aims to observe and analyze the changes induced in Apophis’s surface and rotation by its proximity to Earth’s gravity.
Apophis Went From Being A ‘Planet Killer to Passerby’
The new mission itself can be better explained by the history behind Apophis’s exploration, which was first assumed to be a planet killer. But over the years, it was classified as a ‘near-earth asteroid’ following further studies. The “S-type” asteroid is composed of silicate and nickel-iron materials, distinguishing it from other rocks. Bennu, on the other hand, was carbon-rich.
Discovered in 2004, Apophis was initially believed to be on a collision course with Earth and was classified as a ‘level 4’ on the Torino Scale. However, subsequent modeling in December 2004 ruled out the likelihood of impact. This was conclusively proven in June 2021, when Apophis passed 17 million kilometers from Earth, and NASA promptly removed it from the Earth Close Approaches list.
Apophis originated in the central asteroid belt between Mars and Jupiter, with the latter’s gravity massively altering its gravitational influence over millions of years. This caused it to orbit closer to the Sun and Earth. Thus, its current classification is a near-Earth asteroid rather than a main-belt asteroid.
‘Sample Return’ From Bennu
How OSIRIS-REx returned the Bennu sample is a story straight out of science fiction and a marvel of human ingenuity. OSIRIS-REx was launched on September 8, 2016, flew past Earth on September 22, 2017, and rendezvoused with Bennu on December 3, 2018. It spent the next two years analyzing the surface to find a suitable site to extract a sample.
On October 20, 2020, OSIRIS-REx touched Bennu and collected a sample. It departed Bennu on May 10, 2021, and returned its sample to Earth on September 24, 2023. The sample collection involved a close approach (without landing) to allow the extension of a robotic arm that gathered pieces of rocks and soil from the Bennu surface. The samples weighed less than 60 grams.
On May 10, 2021, the spacecraft departed the Bennu vicinity and began its two-year journey to Earth with the asteroid sample. In September 2023, at 101,000 km (63,000 miles) from Earth, it ejected a capsule containing the sample. The capsule re-entered the atmosphere at 27,650 miles (44498.362-km) an hour and landed under a parachute at the Utah Test and Training Range.
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