OSIRIS striving to bump with Bennu
NASA has sent a robot into space that will hitchhike through the Solar System on the back of an asteroid.
Hurtling along at over 100,000 km/h, NASA’s OSIRIS-REx probe will follow the asteroid Bennu on a two-year round-trip to learn more about the makeup of the giant space rock, and even give some hints about the origin of life on Earth.
The launch was successful, and information is streaming in already. Stay up to date on the official Twitter page.
OSIRIS-REx will return to Earth with up to 2kg of rock samples from Bennu - the largest sample of an asteroid ever collected, which will supply scientists around the world with years’ worth of material to analyse.
NASA loves a fancy name. In this case, the mission has been dubbed the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx); a mouthful that roughly outlines its purpose, but also refers to the Egyptian god Osiris.
The mythological reference “loosely parallels” the OSIRIS-REx mission, according to NASA.
Osiris, in his original form, was believed to have spread knowledge of agriculture throughout the Nile Delta, bringing life to the ancient world. Likewise, OSIRIS-REx seeks to return samples of an asteroid that may contain organic matter central to the origin of life on Earth.
Given that Bennu, the asteroid the probe is chasing, is one of the greatest threats to Earth (it passes close by every few years), the name also mirrors the mythological Osiris’ role as the god of the Underworld and herald of destruction.
The probe launched this morning on the back of an Atlas V 411 rocket from the classic Cape Canaveral site resembles a 3 metre cube with large solar wings. It weighed about a tonne when it took off on its seven-year mission, 505 days of which will see it following Bennu with an array of high-tech instruments trained on the asteroid’s surface.
Two years from now, ORISIS-REx will rendezvous with Bennu, where it will perform surface mapping from a distance of 5 km.
The probe has enough equipment to get about as good a look at the giant space rock as possible. This includes;
- an array of cameras for high-resolution imaging, mapping and recording
- scanning and LIDAR equipment to create 3D topographical maps
- spectrometry equipment that can identify mineral and organic matter from a distance
- a Regolith X-ray Imaging Spectrometer (REXIS) to provide an X-ray spectroscopy map of Bennu
- a robotic arm called TAGSAM - the Touch-And-Go Sample Acquisition Mechanism
Results from two years’ worth of mapping will be used by the research team to pick a site for possibly the most nerve-wracking part of the mission - taking a sample of the asteroid's surface.
OSIRIS-REx will make a close approach to just a few metres from Bennu, where it will extend its robotic arm to gather a sample using TAGSAM, which is a kind of vacuum cleaner that fires nitrogen at the rock, blasting free samples that are quickly sucked up by the arm.
TAGSAM will make three separate sampling attempts to pick up a minimum 60g sample, though it has the capacity to hold up to 2kg, while surface contact pads will collect extra fine-grained material as well.
Collecting this material will be like opening a 'time capsule' from the birth of our Solar System. Bennu was picked because it has not changed much since it was formed, and so is packed with pristine carbonaceous material - the key elements in organic molecules necessary for life to emerge on Earth.
Scientists have seen organic molecules like amino acids in meteorite and comet samples before, suggesting the raw ingredients for life can be naturally synthesised in outer space.
Bennu orbits the Sun about every 1.2 years, but only comes close to Earth every 6 years.
Because of these odd orbital alignments, OSIRIS-REx will gather samples in 2020, but will not leave Bennu until 2021. Two years later, in 2023, the capsule will be drifting down under a parachute in Utah.
The orbit of the asteroid itself is another are of scientific focus.
Scientists have been watching Bennu through telescopes for some time, so its orbit is reasonably well known, but is continually being refined.
It is important to know what Bennu is going to do, after recent calculations produced a cumulative probability of 1 in 1410 (or 0.071 per cent) chance of impact with Earth in the period 2169 to 2199.
The OSIRIS-REx mission will help improve our understanding of non-gravitational effects on orbits, and the implications of those effects for Bennu's collision probability.
One of these effects is called like the Yarkovsky effect, which refers to the influence that an asteroid’s thermal qualities might have on its path through space.
The next few years will yield some exciting new information, but the real fun starts when the samples are delivered to scientists on Earth.
Immediately after touchdown, the capsule will travel to the Johnson Space Center's sample curation department.
The TAGSAM sample head will be carefully removed from the capsule, and the experts say they will feed some of it into the electron microscope on the spot, to get a first glimpse of Bennu.
Over the following six months, the science team will catalogue everything that was brought back, to create a database that will be released to the greater scientific community.
All the different organisations that contributed to the OSIRIS-REx mission will be privy to a small slice of Bennu.
Twenty-five per cent of the sample will go to the OSIRIS-Rex science team to complete their mission objectives, while the remaining 75 per cent will initially go to NASA.
NASA will then divide the portion up, with about 5 per cent staying secure at NASA's facility in White Sands, New Mexico, another 4 per cent going to the Canadian Space Agency as payment for a laser altimeter it provided OSIRIS, while the Japanese Space Agency will receive half a per cent to pore over.
The rest will be set aside for future researchers to search for answers to questions that the science world has not even figured out how to ask yet.
Interested scientists will be able to submit a request to study samples of Bennu, which will be evaluated twice a year by a NASA panel.
Researchers can ask for space rocks in a variety of forms, depending on their goals, they can be dissolved in solution and evaporated out, they can also come in the form of a 30-micron-thick slice of a rock adhered to a glass slide to be studied under a microscope.
If the requested testing is non-destructive, the keeper of the samples will take them back to be used again.
While results will not come through until well into the next decade, the payload OSIRIS-REx brings back will be enough to satiate years of scientific desire, shedding light on the nature of asteroids, the chemicals they carry, and even the possibility that one of Bennu’s older cousins may have seeded life on Earth.