Gathering the OSIRIS-REx pattern return capsule. Credit score: NASA/Keegan Barber, CC BY.
Earth is continually bombarded by fragments of rock and ice, often known as meteoroids, from outer space. Many of the meteoroids are as tiny as grains of sand and small pebbles, and so they utterly deplete excessive within the environment. You possibly can see meteoroids bigger than a couple of golf ball after they mild up as meteors or shooting stars on a darkish, clear evening.
Whereas very small meteoroids are widespread, bigger ones – greater than a dishwasher – usually are not.
Meteoroids are tough objects for aerospace and geophysics researchers like us to review, as a result of we will’t often predict when and the place they may hit the environment. However on very uncommon events, we will research synthetic objects that enter the environment very similar to a meteoroid would.
These objects come from space missions designed to move bodily extraterrestrial samples from outer space to Earth. Due to this similarity to meteoroids in entry, we frequently refer to those pattern return capsules, or SRCs, as “synthetic meteors.”
Over 80 researchers from greater than a dozen establishments not too long ago labored collectively to review such an “synthetic meteor” – NASA’s OSIRIS-REx sample return capsule – because it reentered Earth’s environment.
These establishments included Sandia National Laboratories, NASA’s Jet Propulsion Laboratory, Los Alamos National Laboratory, the Defense Threat Reduction Agency, TDA Research Inc., the University of Hawaii, the Air Force Research Laboratory, the Atomic Weapons Establishment Blacknest, Boise State University, Idaho National Laboratory, Johns Hopkins University, Kochi University of Technology, Nevada National Security Site, Southern Methodist University, the University of Memphis and Oklahoma State University.
This pattern return offered our groups with a novel alternative to measure the sound waves and different phenomena that objects from space produce as they velocity by means of the Earth’s environment.
To seize alerts, we put in many delicate microphones and different devices in key places near the SRC’s flight path.
Whereas space companies and personal firms launch objects into space on a regular basis, the OSIRIS-REx SRC is one in every of solely a handful of objects to return to Earth from interplanetary space because the finish of the Apollo missions. Solely these objects can obtain the velocity of pure meteoroids, making their reentry valuable for finding out the properties of pure objects.
Sampling an asteroid
NASA launched the Origins, Spectral Interpretation, Useful resource Identification, Safety, Regolith Explorer, or OSIRIS-REx, mission on Sept. 8, 2016. It traveled to Bennu, a near-Earth asteroid, and picked up a pattern from its floor in October of 2020.
Associated: NASA’s asteroid Bennu samples have rocks unlike any meteorite ever found
The pattern returned to Earth within the early morning of Sept. 24, 2023, in a pattern return capsule. The SRC reentered Earth’s environment over the Pacific Ocean at a velocity of over 27,000 mph (43,500 kph) and landed in Utah just a few minutes later.
SRCs produce a shock wave as they plunge deep into the environment, akin to the sonic increase generated by a supersonic jet breaking the sound barrier. The shock wave then loses energy till all that is still is low frequency sound, called infrasound.
Whereas people can’t hear infrasound, delicate scientific devices can detect it, even at nice distances. A few of these devices sit on the bottom, whereas others are suspended within the air from balloons.
Observing the Bennu SRC
Our groups of scientists jumped on the SRC reentry as a possibility to study extra about meteors. One of many groups, led by Siddharth Krishnamoorthy at NASA’s Jet Propulsion Laboratory, used the SRC reentry to check infrasound-detecting balloons that might later be used on the planet Venus.
One other crew, led by one in every of us – Elizabeth Silber – and Danny Bowman at Sandia Nationwide Labs used the SRC to higher perceive how we will use sound to [gather information about meteoroids].
Researchers from many establishments throughout the nation participated in these observational campaigns.
Our groups strategically positioned devices in places throughout a 300-mile (482 km) distance spanning from Eureka, Nevada, to shut to the touchdown web site in Utah. The devices ranged from high-tech customized sensors to smartphones on the bottom across the SRC’s flight path and touchdown web site. They monitored the low frequency sound waves from the SRC’s reentry.
Along with the ground-based sensors, our researchers connected devices to balloons that floated at twice the altitude of economic planes through the SRC reentry. The sensors connected to those balloons recorded the sound waves produced by the SRC’s shock wave. These sound waves carried details about the SRC, its motion and the surroundings it handed by means of.
The balloon groups needed to time the balloons rigorously to verify they’d be on the proper place when the SRC handed. Group members from NASA’s Jet Propulsion Laboratory, Oklahoma State University and Sandia National Laboratories launched a number of totally different sorts of balloons earlier than daybreak from Eureka, Nevada.
Researchers from OSU, Sandia and the University of Hawaii additionally deployed floor infrasound sensors nearer to the SRC’s touchdown location, alongside the Utah-Nevada border and at Wendover Airport. Whereas the SRC was already slowing down and Wendover Airport was about thrice farther from the flight path than the Eureka deployment, we detected a transparent infrasound sign at this web site as effectively.
Researchers on these groups at the moment are analyzing the information to establish the factors alongside the trajectory the place devices recorded the SRC reentry alerts. As a result of the SRC’s flight path spanned roughly 300 miles (482 km), the researchers want to determine the origin factors of the alerts because the totally different sensors detected them.
This was the most-instrumented hypersonic reentry in history.
This analysis will assist our groups work out what patterns the low-frequency sound waves propagated by means of the environment and the place the shock wave was at its peak depth.
Whereas our groups are nonetheless analyzing the information, the preliminary outcomes present our devices captured plenty of alerts that can assist future analysis use low-frequency sound waves to review meteors.
And gaining insights into intricacies about how low-frequency sound waves journey by means of the environment may also help researchers use infrasound to detect hazards on Earth, such as tornadoes and avalanches.
This text first appeared on The Conversation. It’s republished right here beneath a Artistic Commons license.
