{"id":15292,"date":"2016-08-23T22:45:08","date_gmt":"2016-08-23T14:45:08","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/one-of-nasas-cleanest-spacecraft-ever-is-ready-to-fly\/"},"modified":"2016-08-23T22:45:08","modified_gmt":"2016-08-23T14:45:08","slug":"one-of-nasas-cleanest-spacecraft-ever-is-ready-to-fly","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/one-of-nasas-cleanest-spacecraft-ever-is-ready-to-fly\/","title":{"rendered":"One of NASA\u2019s cleanest spacecraft ever is ready to fly"},"content":{"rendered":"
\"A
A member of the OSIRIS-REx team prepares the spacecraft for launch Sept. 8. The Atlas 5 rocket\u2019s payload fairing is in the background. Credit: Ben Cooper\/Launchphotography.com<\/figcaption><\/figure>\n

Five years after winning $1 billion from NASA to mount the first U.S. asteroid sample return mission, scientists and engineers will get their last look at the OSIRIS-REx spacecraft this week as it is closed up inside the nose cone of an Atlas 5 rocket for launch in September.<\/p>\n

The probe\u2019s encapsulation inside the Atlas 5\u2019s payload fairing marks the end of a multi-year campaign to ensure every piece of the spacecraft meets stringent cleanliness standards. During construction, engineers tracked contaminants wherever OSIRIS-REx went on Earth, all the way down to concentrations measured in parts per billion.<\/p>\n

Experts were especially concerned with organic residue left behind by humans and certain materials, like nylon and adhesives, normally used in the assembly of satellites.<\/p>\n

OSIRIS-REx will bring back specimens for researchers to interrogate inside high-tech labs around the world, seeking clues about the origin of life, water and the planets themselves. The results could be skewed by an unexpected microbe or spore from planet Earth.<\/p>\n

Small clumps of matter formed from a cloud of dust and gas at the dawn of the solar system. These proto-worlds grew into larger objects \u2014 and some became full-fledged planets \u2014 as they collided with one another, accreting more and more material along the way. Scientists believe asteroids brought the ingredients of life to Earth.<\/p>\n

Analysts will look for amino acids \u2014 the building blocks of proteins \u2014 simple and complex organic compounds, and other markers from asteroid Bennu, an object orbiting the sun relatively close to Earth that managers selected as OSIRIS-REx\u2019s target.<\/p>\n

\u201cThe core of OSIRIS-REx is to return a sample to the Earth to understand the origin of the solar system, and the origin of life perhaps, and to do that we need a pristine sample,\u201d said Jason Dworkin, OSIRIS-REx project scientist at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.<\/p>\n

For scientists and engineers working on OSIRIS-REx, this week is a turning point. It\u2019s the last time they will see the spacecraft \u2014 the product of 12 years of research and development \u2014 but it also means their long-held worries about contaminating the probe are nearly over.<\/p>\n

\u201cIt\u2019s incredibly emotional,\u201d Dworkin said.<\/p>\n

\u201cIt\u2019s hard not to tear up around the spacecraft, but I don\u2019t want to contaminate it,\u201d he joked.<\/p>\n

The schedule calls for the 4,651-pound (2,110-kilogram) spacecraft, already filled with hydrazine fuel for delicate in-space maneuvers, to be lifted on to an attach fitting this week inside the Payload Hazardous Servicing Facility at NASA\u2019s Kennedy Space Center, then enclosed within the Atlas 5\u2019s 13-foot diameter (4-meter) nose fairing.<\/p>\n

\u201cWe have a completely fueled spacecraft that\u2019s ready to go,\u201d said Rich Kuhns, OSIRIS-REx program manager at Lockheed Martin, which built the spacecraft. \u201cOver the next few days, what\u2019re going to do is we\u2019re actually going to lift the spacecraft onto the mechanism that will separate it from the top of the Centaur stage. Then we\u2019re going to. .. close it up inside of the fairing, which will then get shipped over to the launch pad and stacked on top of the overall rocket.\u201d<\/p>\n

Ground crews will position the OSIRIS-REx spacecraft between two halves of the fairing, which will peel away in flight like a clamshell, then seal the probe inside.<\/p>\n

\u201cThis is the last chance really for anybody on Earth to see that hardware until the sample is back in 2023, and only the return capsule is coming back,\u201d said Dante Lauretta, OSIRIS-REx principal investigator from the University of Arizona.<\/p>\n

\"Dante
Dante Lauretta, OSIRIS-REx principal investigator from the University of Arizona. Credit: NASA\/Joel Kowsky<\/figcaption><\/figure>\n

On Aug. 29, technicians will transport the spacecraft inside the fairing to the Vertical Integration Facility at Cape Canaveral\u2019s Complex 41 launch pad, where a crane will hoist the payload atop the Atlas 5.<\/p>\n

Engineers plan to pluck the final \u201cremove before flight\u201d covers from OSIRIS-REx\u2019s instruments and sensors before encapsulation. The last time anyone will put hands on the spacecraft before launch will come in the predawn hours of Sept. 6, when a technician will crawl through a special access door cut into the Atlas 5 fairing to activate OSIRIS-REx\u2019s battery system.<\/p>\n

A United Launch Alliance Atlas 5 rocket will kick off the probe\u2019s seven-year journey Sept. 8. The two-hour launch window opens at 7:05 p.m. EDT (2305 GMT), and the mission has until Oct. 12 to depart Earth or else wait a year for the next opportunity.<\/p>\n

OSIRIS-REx will return to the vicinity of Earth in September 2017 for a gravity assist, slingshotting the probe toward asteroid Bennu, a miniature world about 1,600 feet (500 meters) across. Bennu is a rare kind of object \u2014 scientists know it as a \u201cB-type\u201d asteroid \u2014 and is likely loaded with lots of carbon, the backbone of organic molecules.<\/p>\n

In August 2018, the solar-powered voyager will begin its final approach to the asteroid, and eventually slip into orbit.<\/p>\n

After a thorough survey of Bennu with OSIRIS-REx\u2019s spectrometers, cameras and laser altimeter, scientists will decide where to snag a sample.<\/p>\n

The payload package will look for organics and collect detailed temperature measurements all across Bennu, which has regions colder than an icebox and others hot enough to boil water.<\/p>\n

The asteroid has a surface area of about 200 acres \u2014 0.78 square kilometers \u2014 and some of OSIRIS-REx\u2019s instruments will capture data with centimeter-scale resolution, or better. The observations will add context to the sample OSIRIS-REx will return to Earth, and identify resources that might be valuable for astronauts in the future.<\/p>\n

During the next phase of the mission, in late 2019, mission scientists will narrow down targets for OSIRIS-REx to go down and snatch up a piece of Bennu. A final decision by top NASA management will pick the sampling site based on several factors, primarily to avoid damaging the spacecraft and to maximise the likelihood of capturing primitive, pre-biotic material, the mission\u2019s scientific payoff.<\/p>\n

Keiko Nakamura-Messenger, a space scientist working at NASA\u2019s Johnson Space Center in Houston, leads the group charged with recommending a place on Bennu to sample.<\/p>\n

\u201cWe want to identify an area which has a high concentration of organics and a variety of minerals, so that we can answer the scientific questions, or at least as many as possible,\u201d Nakamura-Messenger said in an interview with Spaceflight Now.<\/p>\n

There are limitations, however, on where OSIRIS-REx can go. The mechanism aboard the probe to gather the asteroid specimens can only handle rocks up to three-quarters of an inch \u2014 about 2 centimeters \u2014 in diameter, so officials prefer a site with fine dust grains or a gravelly outer layer.<\/p>\n

\u201cWe don\u2019t need a big rock,\u201d Nakamura-Messenger said. \u201cWe just need the signature of those organics.\u201d<\/p>\n

When NASA gives the green light to send OSIRIS-REx to the sampling site, a device called the TAGSAM will swing into action. Mounted on the end of of an articulating 11.1-foot (3.4-meter) robot arm, TAGSAM is about the size of a dinner plate, resembling an air filter affixed to an antique automobile.<\/p>\n

TAGSAM is short for the Touch and Go Sample Acquisition Mechanism.<\/p>\n

Starting from a point a few thousand feet \u2014 less than a kilometer \u2014 from Bennu, the spacecraft will fire thrusters to leave orbit, then adjust its speed to match the asteroid\u2019s rotation, allowing OSIRIS-REx to hover over the sampling target as it goes in for the prize, a sporty approach currently scheduled some time around July 4, 2020.<\/p>\n

\u201cWe feel that gives us almost two years at the asteroid to map it with precision and help us in our decision where to go, then rehearse and refine the sampling attempt,\u201d Lauretta said.<\/p>\n

\"Artist's
Artist\u2019s concept of the OSIRIS-REx spacecraft with the TAGSAM sampling arm deployed. Credit: NASA<\/figcaption><\/figure>\n

The descent will be slow and methodical. Bennu\u2019s tenuous gravity will pull on the spacecraft at just 10 micro-g, equivalent to ten one-millionths the strength of Earth\u2019s gravity, making the approach more like rendezvous with the space station than landing on another planet.<\/p>\n

\u201cIts very much like a docking,\u201d Lauretta said. \u201cWe\u2019re under our own thrust authority the whole time. The gravity field is, more or less, insignificant at that point.\u201d<\/p>\n

OSIRIS-REx will reach Bennu\u2019s surface at a velocity of approximately two-tenths of a mph \u2014 10 centimeters per second \u2014 a fraction of a normal walking pace. The spacecraft will not stay there for long, taking just five seconds for TAGSAM to do its job as the nozzle contacts the asteroid.<\/p>\n

A bottle of compressed nitrogen gas will discharge during the touch-and-go maneuver, scouring up bits of dust and rock from up to 8 inches (20 centimeters) beneath Bennu\u2019s surface, where material should be shielded from wild temperature swings that could damage sensitive organics.<\/p>\n

The TAGSAM nozzle will trap samples blown away by the pulse of nitrogen and suck them into a collector with a rush of air, similar to the way a vacuum cleaner works. A camera aimed at the collector will record how it works at one frame per second. The imagery, coupled with precise measurements of changes in the spacecraft\u2019s mass, will tell engineers how the device performed.<\/p>\n

The criteria for success? 2.1 ounces, or 60 grams, of goods.<\/p>\n

That\u2019s enough for scientists back on Earth to try and unravel the constituents and history of Bennu, an object experts believe is representative of the mountain-sized boulders that populated the early solar system, when bodies buzzed through space like billiard balls, bombarding the proto-planets that later became Earth and its neighbors.<\/p>\n

Tests of the TAGSAM before launch showed the mechanism should collect many times more than the minimum requirement of 60 grams. If scientists are not satisfied with the first try, OSIRIS-REx carries two backup nitrogen canisters for additional sampling attempts.<\/p>\n

\u201cIn their testing, they routinely picked up 300, 400 or 500 grams (10 to 17 ounces), so I\u2019m expecting hundreds of grams of sample,\u201d Lauretta said.<\/p>\n

\u201cWe feel like we\u2019ve designed it to the worst-case scenario, but you don\u2019t know until you try,\u201d Lauretta said. \u201cIt\u2019s such a nail-biting moment. If we go down and everything works and we collect a sample, we don\u2019t want to do anything to risk that material. We just spent all this time, and all this money, to get that sample in, and that alone represents our science. That sample is extremely valuable, and the last thing I want do is go in for more and lose everything.\u201d<\/p>\n

Once the sample is captured, controllers will send commands for the TAGSAM arm to place the collection canister inside OSIRIS-REx\u2019s landing capsule. Explosive bolts will sever the TAGSAM head from the craft\u2019s robotic arm, and the capsule\u2019s lid will close over the device for the trip home.<\/p>\n

\"Technicians
Technicians and engineers install a solar panel on the OSIRIS-REx spacecraft. Credit: NASA\/Ben Smegelsky<\/figcaption><\/figure>\n

The mission will move on to other tasks if it scoops up enough material the first time, including a measurement of the forces impacting Bennu\u2019s orbit to better predict its future path. There is a 1-in-2,700 chance the asteroid will impact Earth late in the 22nd century, and OSIRIS-REx will try to refine that probability.<\/p>\n

Engineers put stringent controls on the cleanliness of the OSIRIX-REx spacecraft, especially the parts that will touch the asteroid specimens, to ensure the material comes home unaltered by chemicals that could erase the organic signals sought by the science team.<\/p>\n

According to Kuhns, the cleanliness protocols were one of the mission\u2019s biggest challenges.<\/p>\n

\u201cA lot of it impacted how we build,\u201d Kuhns said.<\/p>\n

He says engineers who designed the spacecraft could not use many of the lubricants and glues they would on a typical mission. On one part of the TAGSAM system, for example, technicians could not use a preferred type of epoxy glue, so engineers selected the right set of screws, inserts and metals to add extra torque to certain fasteners, bypassing the need for an adhesive.<\/p>\n

\u201cThe whole goal is to get the sample from the asteroid and bring it back safely, so we are carrying extremely tight contamination requirements that go well above and beyond what we typically have,\u201d Kuhns said in an interview. \u201cWe have to watch amino acids, and specific organic constituents, because that\u2019s what we\u2019re trying to find out about the asteroid.\u201d<\/p>\n

Engineers also substituted lock wires for glues, and workers had to replace nylon tethers used in pre-launch processing with other ways of securing tools and parts.<\/p>\n

\u201cThat tether we\u2019ve used for 30 years, we couldn\u2019t use any more,\u201d Kuhns told Spaceflight Now.<\/p>\n

Realizing the mission\u2019s super-clean standards, ground crews kept the TAGSAM unit that will fly to Bennu separate from the rest of OSIRIS-REx until the very end of the spacecraft\u2019s assembly campaign to avoid potentially spoiling the hardware with Earth microbes.<\/p>\n

Dworkin said scientists hope to get back a sample from Bennu just as the material exists on the asteroid.<\/p>\n

\u201cTo understand what things were like on the early Earth and in the early solar system, we have to go to objects that still exist in a primordial pristine date that haven\u2019t been perturbed by geology,\u201d Dworkin said. \u201cMeteorites deliver that information to the Earth from asteroids, but they invariably land on the ground and become instantly contaminated with terrestrial biology, and atmospheric entry to the Earth.\u201d<\/p>\n

Researchers can still glean some results from analyzing meteorites, and teams have found amino acids in space rocks that fell to Earth.<\/p>\n

Engineers did not sterilize the OSIRIS-REx spacecraft \u2014 a costly step that NASA ordered before it launched the Viking landers to Mars in the 1970s \u2014 but they took other measures to ensure the asteroid probe leaves Earth as clean as possible.<\/p>\n

Scientists have archived some of the materials used during assembly of the OSIRIS-REx spacecraft, and workers installed collection plates throughout the probe\u2019s construction facility near Denver and inside the clean room at Kennedy Space Center.<\/p>\n

\"Artist's
Artist\u2019s concept of the OSIRIS-REx sample return canister streaking through Earth\u2019s atmosphere. Credit: NASA\/University of Arizona<\/figcaption><\/figure>\n

The plates accumulated contaminants from the atmosphere around OSIRIS-REx, and researchers will hang on to them until the mission returns with bits of Bennu in 2023. Scientists even sequenced some of the DNA found inside OSIRIS-REx\u2019s clean room, according to Dworkin.<\/p>\n

The idea is to archive the materials for future scientists to compare against the asteroid specimens, helping them rule out any false detection.<\/p>\n

Loaded with celestial goodies, OSIRIS-REx\u2019s 100-pound (60-kilogram) sample return canister will blaze into Earth\u2019s atmosphere at around 9 a.m. Mountain time on Sunday, Sept. 24, 2023. A recovery team will await the capsule at a landing site in Utah, then ship the carrier to NASA\u2019s Johnson Space Center in Houston, where scientists will first open the canister.<\/p>\n

Researchers will use optical and electron microscopes, super-computing labs, and synchrotron accelerators \u2014 instruments the size of a large room or a building \u2014 in their asteroid sample analysis.<\/p>\n

Scientific equipment qualified to fly in space have to operate in extreme temperatures, an airless vacuum, and intense radiation, all while functioning on very little power.<\/p>\n

\u201cInstrument designs are frozen years before the spacecraft is launched,\u201d Dworkin said. \u201cFurthermore, those instruments have to be built on known heritage. They have to work, and they have to work perfectly. That means they\u2019re no longer state-of-the-art. They\u2019re state-of-the-art in terms of being tiny, and working under the harshest conditions with the lowest power margins.<\/p>\n

\u201cIt\u2019s amazing what they can do, but when you bring something to a laboratory that has kilowatts of equipment, that takes us half a room or even an entire building, and require a staff just to keep them running, you can measure things at tremendously higher precision and higher accuracy,\u201d Dworkin said.<\/p>\n

For example, scientists will attempt to determine the chirality, or handedness, of amino acids and other compounds grabbed from Bennu. Molecules associated with life, such as DNA, have a distinctive orientation. In the case of DNA in organisms on Earth, the double helix always twists in a right-handed direction, and the atoms that make up amino acids in biology are almost always left-handed.<\/p>\n

The preference for a left or right orientation among the atoms making up biological molecules makes it easier for chemicals to latch together and build more complex structures.<\/p>\n

\"rtist's
Artist\u2019s concept of excess left-hand aspartic acid created in asteroids and delivered to Earth via meteorite impacts. The line at the bottom is a chromatogram showing that left-hand aspartic acid (tall peak in the center, with diagram of left-hand aspartic acid molecule on top) was four times more abundant in the meteorite sample than right-hand aspartic acid (smaller peak to the left, with right-handed aspartic acid molecule on top). Credit: NASA\/Hrybyk-Keith, Mary P.<\/figcaption><\/figure>\n

But the reasons why molecules involved in biology are almost always left- or right-handed, depending on the compound, remain a mystery.<\/p>\n

\u201cThere are a few different amino acids which have been seen that have an excess of left-handed chirality in a variety of meteorites. Never an excess of the right-handed, always the left,\u201d Dworkin said. \u201cThat makes you wonder is there a solar system process that makes left preferential. We\u2019ve looked at a variety of meteorites and always seen an excess of left, or no excess, in the amino acids.\u201d<\/p>\n

But the concern over contamination raises a red flag when scientists are studying meteorites. Thanks to the extensive cleanliness protocols institute before launch, that won\u2019t be the cause with the samples returned by OSIRIS-REx.<\/p>\n

\u201cThere are amino acids where you see a left excess (in handedness), but you don\u2019t know if you can believe it because the easiest explanation is to say it\u2019s contaminated,\u201d Dworkin said. \u201cYou have to go to extensive lengths to prove that it\u2019s not contamination. Sometimes you just can\u2019t do it. Being able to say, with certainty, that we can see that there\u2019s an excess in this compound, and that compound, but not this other compound, will help us understand the mechanisms that led into making these products.\u201d<\/p>\n

If life-supporting molecules found on Bennu show the same handedness of similar compounds on Earth, scientists might conclude the mechanism that triggered their excessive left or right orientation is  a natural occurrence, and not just chance.<\/p>\n

\u201cAmino acids are really interesting in their chirality,\u201d Dworkin told Spaceflight Now. \u201cThere\u2019s also some reports of some sugar acids and related compounds that have a chiral excess. But this is the only natural non-biological process where\u2019s there\u2019s evidence of chiral excess, so how that formed is a great mystery of science that we need to address.\u201d<\/p>\n

\u201cWe need these samples in our laboratories,\u201d Lauretta said. \u201cWe\u2019re having a conversation about chirality, which is the handedness of key organic molecules, and life has a particular preference for one mirror image over the other. You can\u2019t fly an instrument on a spacecraft to make that kind of measurement.\u201d<\/p>\n

Email the author.<\/i><\/b><\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

A member of the OSIRIS-REx team prepares the spacecraft for launch Sept. 8. The Atlas 5 rocket\u2019s payload fairing is in the background. Credit: Ben Cooper\/Launchphotography.com Five years after winning $1 billion from NASA to mount the first U.S. asteroid sample return mission, scientists and engineers will get their last look at the OSIRIS-REx spacecraft […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[1874,724,3600,1526,3623,1736,2017,3624],"class_list":["post-15292","post","type-post","status-publish","format-standard","hentry","category-news","tag-astrobiology","tag-atlas-5","tag-av-067","tag-bennu","tag-chirality","tag-complex-40","tag-dante-lauretta","tag-jason-dworkin"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15292"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=15292"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15292\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=15292"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=15292"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=15292"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}