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IIn most scientific disciplines, if we want to examine an object closely and in depth, we can collect some kind of sample of that object, take it to our laboratories, and perform any number of direct analysis tests of that sample. For the most part, in astronomy we can’t do that; we usually limit ourselves to examining objects from very far away, usually examining the light we receive from them. The one exception to this comes from meteorites, where, in essence, the objects have reached us, and in fact, as explained in previous presentations of “Special Topics”, we have learned quite a bit about the various “little bodies” in our solar system, and also a little on the moon and Mars, as a result of laboratory analysis of the meteorites that were collected.
With meteorites, of course, we are limited to whatever nature decides to send us; if we want samples from anywhere else, we have tor go out and pick them up somehow. The only thing we’ve done this in is the moon: the moon landing Apollo missions in the late 1960s and early 1970s returned over 382 kg of lunar samples, most of which still inside storage and remaining to be examined – and three unmanned Luna probes (Moon 16, 20, is 24) from the then Soviet Union during the first half of the 1970s returned another 300 grams of lunar samples. Just last week, China launched its Change 5 mission to collect lunar samples and, if successful, it is expected to return them shortly after mid-December. Meanwhile, the Perseverance rover launched last July is expected as the first sToe in a joint NASA / ESA multi-mission attempt for to collect Martian champions for returning to Earth towards the end of this decade.
So far, there have been four spacecraft missions that have been carried out with the intent of collecting and returning samples from the “small bodies” of the solar system. The first of these was that of NASA Stardust mission, which was launched on February 7, 1999, and which went through the coma of Comet 81P / Wild 2 – week 1 “Comet of the week“- January 2, 2004. Using an extremely light and porous substance called” airgel “Stardust collected over a million samples of dust particles from the coma of comet 81P, and then returned them to Earth on January 15, 2006. The Stardust mission as a whole is discussed in a precedent “Special topics“And the specific results of the analyzes of the returned samples are discussed in the Comet 81P” Comet of the Week “presentation.
The second mission was from JAXA Hayabusa mission, which was launched on May 9, 2003, and which landed at the Apollo-type asteroid (25143) Itokawa in September 2005. Hayabusa was plagued by various difficulties but during one of his brief landing attempts he managed to collect around 1500 grains (with a total mass of just under a gram) of surface material, which eventually returned to Earth on June 13, 2010. The Hayabusa mission as a whole is discussed in a precedent “Special topics“Presentation.
The remaining two sample collection missions are underway right now. The first of these is JAXA’s Hayabusa2 mission, which was launched from Tanegashima Space Center in southern Japan on December 3, 2014. Hayabusa2’s destination was the Apollo-type asteroid (162173) Ryugu, discovered May 10, 1999 by LINEAR program in New Mexico (and later named for the Dragon Palace from Japanese folk tales); is a approximately spherical object about 1 km in diameter and is a primitive dark colored object somewhat similar to carbonaceous chondrite meteorites (discussed in a previous “Special topics“Presentation). Hayabusa2 arrived at Ryugu on June 27, 2018 and entered orbit around it.
While not all aspects of Hayabusa2’s planned mission profile went as planned, overall it was far more successful than its predecessor. On 21 September 2018, Hayabusa2 successfully distributed two small ones MIcro-Nano Experimental robot vehicle for Asteroid rover (MINERVA) Ryugu ‘S. surface, and two weeks later it also fielded the largest German-built Mobile Asteroid Surface Scout (MASCOT) rover. All three of these worked as intended, with several scientific instruments aboard MASCOT performing detailed scientific investigations. Meanwhile, Hayabusa2 herself briefly landed twice Ryugu’s surface, once on February 21, 2019, to collect surface samples, and again on July 11, 2019, to collect sub-surface material that had been exposed by a previously distributed impact. Both of these operations were successful and a third landing and sample collection maneuver was deemed unnecessary and therefore was canceled.
Hayabusa2, with its collected material samples, left Ryugu on November 13 2019, and it should be back back to Earth next week, December 6th. In this case, the capsule containing the sample materials is expected to be released, which will then land at Woomera Test range in South Australia, where they can be retrieved and later sent for analysis. There is enough propellant remained in the main spacecraft such that after passing from Earth it will be sent to a high-speed overflight of the Apollo-type asteroid (98943) 2001 CC21 in July 2026 and an encounter with another Apollo-type asteroid, 1998 KY26, in July 2031.
The other current mission is NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRISREx), which launched from Cape Canaveral, Florida on September 8, 2016. OSIRISREx’s the destination was the Apollo-type asteroid (101955) Determinant, discovered by LINEAR on September 11, 1999; following a worldwide naming competition, he received the bird-shaped Egyptian deity name suggested by 9-year-old North Carolina student Michael Puzio. Like it Ryugu, Determinant it is also approximately spherical in shape, but it is slightly smaller, being about 500 meters in diameter; it too is a primitive and dark-colored object.
OSIRISREx arrived at Determinant on December 3, 2018, although it did not enter orbit around it until the end of that year. OSIRISREx contains a suite of scientific instruments that have played an extensive range of surveys of Determinant, and among one of the first results was the presence of substances related to water Bennu’s surface in the form of hydrated clays, a result consistent with the results of some recent ground studies. In early 2019, when Determinant was near perihelion, OSIRIS-REx detected several comet-like eruptions of dust grains and larger particles Bennu’s surface, indicating that Determinant it can be considered one of the “active asteroids” object of next week’s “Special Topics” presentation.
One of the primary elements of OSIRIS-REx mission is collecting samples from Bennu’s surface, a task that turned out to be a little more difficult than expected due to the fact that the surface it contains a large number of boulders and not much in the way of “smooth” areas. Four potential sites wwere identified in August 2019, with the final selection of the site nicknamed “Nightingale” made in December. By means of a Touch-and-Go Sample Acquisition Mechanism (TAGSAM), in which short bursts of nitrogen gas were fired at the surface, OSIRIS-REx successfully collected well over 200 grams of surfexceptional material last October 20th.
OSIRISREx is exshould remain in the vicinity of Determinant for a few more months, with a current scheduled departure date of March 3, 2021. The arrival on Earth is scheduled for September 24, 2023, at which time the capsule containing the acquired samples will be deployed into the atmosphere, with landing scheduled for Utah Test and Training Camp west of Salt Lake City. From there, the recovered samples will be delivered to various laboration facilities for analysis.
At this time there is another champion return mission of “little bodies” in development, the JAXA Martian Moons Exploration (MMX) mission. As currently planned, MMX will launch in September 2024 and upon arrival on Mars orbit the following year will attempt one or two landing maneuvers to collect samples. Phobos, with the aim of collecting up to 10 grams of material. Next, MMX will run several flybys of We say before leaving the orbit of Mars in August 2028 to return to Earth in July 2029.
Incidentally, (162173) Ryugu it will pass 0.061 AU from Earth on December 29, although it will remain a relatively faint object of 17th size. Meanwhile, (101955) Determinant, which exceeded 0.015 AU from Earth a week and a half after its discovery, has been identified as a Potentially dangerous asteroid (in the full sense of that term), and can make very close approaches to Earth on occasion, including one of 0.005 AU on September 23, 2060. The possibility of an impact on Earth at some point in the future after that date remains a possibility. , although numerical simulations point to a more likely fate than impact on the sun one day. If one day an impact on Earth were to become a realistic scenario, perhaps the information gathered by OSIRIS-REx will help determine the appropriate Actions humanity will have to take.
More from week 49:
This week in history Comet of the week Download free PDF Glossary
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