Автор Anatoly Zak, 26.05.2011 08:53:55

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March 30, 2012

System Definition Reviews: Key Checkpoints on the Way to a Successful Mission


The GSRT helps the teams think through their systems, and challenges the groups to strengthen all aspects of their design.

This week the OSIRIS-REx mission team began the first of a series of meetings that will run for a month or so -- the System Definition Reviews or SDRs. Each instrument will have its own day long SDR - OCAMS, OTES, OVIRS, OLA, REXIS and even the Touch-and-go Sample Mechanism, TAGSAM. These instrument SDRs will lead up to the overall Mission Definition Review, or MDR, in May.

The System Definition Reviews are one of the key checkpoints during Formulation - the period when large NASA projects, like OSIRIS-REx, work to carefully refine their design prior to the next phase, Implementation. Formulation will continue for about another year, concluding with a series of preliminary design reviews and a confirmation review. After the transition to Implementation, we will finalize our designs and begin assembling the spacecraft and NASA will go shopping for the rocket that we will need to get off the pad in 2016.

The SDRs are our first meetings with the GSRT, or Goddard System Review Team, an independent panel of experts from Goddard Space Flight Center who will help us identify weaknesses in our plans, and point them out before they become problems. We will meet with the GSRT many times before our mission begins in just over four years.

Sometimes these formal reviews seem endless, but there is a well-established process at work here. Each review is designed to incrementally push us along towards a completed, well-thought-out mission. Right now, the system is driving us towards carefully refined requirements and the more concrete designs that will be transformed into the operational OSIRIS-REx spacecraft.

This is also a good time to mention the technical discipline that created the need for these reviews, systems engineering. Wikipedia says systems engineering "is an interdisciplinary field of engineering focusing on how complex engineering projects should be designed and managed over their life cycles." NASA was faced with the enormously complicated task of bringing together the fields of mechanical, electrical, optical, software, and chemical engineering, along with requirement to address the needs of cost control, mission and personal safety, quality and performance. Managers quickly recognized the importance of systems engineering techniques in spanning the differing (and sometimes conflicting) practices found in the individual disciplines needed to successfully launch a spacecraft.

Cat Merrill, the Senior Systems Engineer for the OCAMS reviews the day's agenda.

David Everett is the Project Systems Engineer for OSIRIS-REx, and he helps the team navigate the reviews to satisfy NASA's systems engineering requirements. The spacecraft and each instrument team also have their own systems engineers who work to ensure their programs connect cleanly with the mission-level processes.

The SDRs we began this week are an important part of NASA's systems engineering process, and are key to helping us ensure the OSIRIS-REx mission will be a success.


NASA Mission Wants Amateur Astronomers to Target Asteroids



April 10, 2012
Lunar and Planetary Science Conference: Networking, the OSIRIS-REx mission, and asteroid science
ЦитатаEvery year members of the planetary science community meet in Houston, Texas to share their research, foster collaborations, and strengthen pre-existing ones. This tradition started in 1970 when scientists met to discuss work done on Moon rocks returned by the NASA Apollo missions. The annual Lunar and Planetary Science Conference (LPSC) has grown each year - this year's conference was attended by more than 1,700 scientists from all over the world. While the first conferences may have concentrated on lunar science, today a multitude of planetary science topics are covered, from studies of tiny grains of stardust that formed before the Solar System (presolar grains), to remote sensing studies of other planets, and astronomical observations of asteroids. This year the 43rd LPSC was held in conjunction with the Nuclear and Emerging Technology for Space (NETS) topical meeting to celebrate the first 50 years of nuclear-powered space flight.

PI Dante Lauretta discusses the OSIRIS-REx mission at the LPSC.

Not only is LPSC the ideal place to talk science, it's also a great opportunity for scientists to meet with their friends and colleagues (both past and present). In this technological age it's easy to write a scientific paper with someone on another continent via email and video chat - but conferences are the perfect opportunity to sit down and talk with co-authors and collaborators face-to-face. This year's LPSC provided the perfect opportunity for OSIRIS-REx mission scientists to interact with other scientists, NASA officials, and each other.

A number of OSIRIS-REx mission team members participated, including Principal Investigator Dante Lauretta, mission sample scientist Harold Connolly Jr., spectral analysis lead Vicki Hamilton, and asteroid scientist Carl Hergenrother. Dante Lauretta spent one of the evening poster sessions talking to planetary scientists of all generations about the OSIRIS-REx mission. Team members from the Canadian Space Agency were also there to talk about their instrument OLA (OSIRIS-REx Laser Altimeter - click here to read more about it)! Dante Lauretta spoke about OSIRIS-REx the team's work in a session dedicated to the study of small bodies such as asteroids and moons (including Mars' moons, Phobos and Deimos). Dante spoke about the target for the OSIRIS-REx mission - (101955) 1999 RQ36 - a carbonaceous B-type Apollo near-Earth asteroid. He presented a characterization of the photometric properties (i.e., how the asteroid reflects light) of 1999 RQ36 at visible wavelengths including the determination of its rotation period.

The OSIRIS-REx mission wasn't the only asteroid mission represented at LPSC this year - the DAWN mission had three dedicated oral sessions where scientists working on data sent back by the DAWN spacecraft could present their results to the wider planetary science community. DAWN is a NASA spacecraft that is currently exploring and studying Vesta, one of the largest members of the asteroid belt asteroid. Dawn will depart Vesta later this year and rendezvous with the dwarf planet Ceres in early 2015. Scientists packed the conference rooms to capacity while images, spectral maps, and compositional data from the spacecraft were presented. Data collected from the mission were also compared to a group of meteorites called the HEDs which are believed to originate from Vesta; data presented at LPSC this year support this theory.

Previous conferences have had special oral sessions dedicated to other comet/asteroid missions such as STARDUST and Hayabusa. We all look forward to the year when the OSIRIS-REx mission will have its own dedicated sessions at LPSC!

View our most recent news items by visiting the news archive here!


Asteroid 2005 YU55 11/08/12.
Credit: UA/LPL/Catalina Sky Survey/R. Hill.

Amateur astronomer Tim Hunter.
Credit: Tim Hunter.

April 16, 2012
ЦитатаAmateur astronomers are about to make observations that will affect current and future space missions to asteroids.

Some will use custom-made, often automated, telescopes equipped with CCD cameras in their backyards. Others will use home computers to make remote observations with more powerful telescopes states or continents away. Many belong to leading national and international amateur astronomy organizations with members ranging from retirees to school kids.

Researchers on NASA's robotic asteroid sample return mission, OSIRIS-REx, are turning to amateur astronomers for new data on near-Earth asteroids in a citizen science observing campaign called "Target Asteroids!" The campaign starts in April 2012 and will last at least to the end of this decade.

The full name of the OSIRIS-REx mission is Origins Spectral Interpretation Resource Identification Security - Regolith Explorer. The OSIRIS-REx spacecraft is to launch in 2016, reach a well-characterized primitive asteroid called (101955) 1999 RQ36 in 2019, examine that body up close during a 505-day rendezvous, then return at least 60 grams of it to Earth in 2023.

"Asteroids are a rich and accessible historic archive of the origin of our Solar System and life, a valuable source of mineral resources, and potentially hazardous Earth impactors that civilization must learn to deal with," said OSIRIS-REx Principal Investigator Dante Lauretta of the University of Arizona. "Our mission will address all these issues."

1999 RQ36 -- a 500-meter-diameter, dark carbonaceous asteroid -- is difficult for even powerful Earth-based telescopes to observe at this time because it is relatively distant from Earth.

Amateur astronomers are asked to observe asteroids selected because they are in near-Earth orbits that can be reached by current-generation spacecraft and are at least 200 meters in diameter, said Target Asteroids! scientist Carl Hergenrother, head of the OSIRIS-REx astronomy working group.

Precise orbits, sizes, rotation rates, physical composition and other important characteristics for these asteroids are largely unknown. Seventy-four asteroids are listed now, but the list will grow as observers get more information on known asteroids and discover new ones, Hergenrother said.

"We want amateur astronomers to do astrometry (which precisely measures positions of objects), photometry (which measures brightness) and spectroscopy (which measures the colors, or wavelengths, of light) to discover as much as we can about these objects," he said.

"These will be challenging objects to observe because they are very faint," said Target Asteroids! coordinator Dolores Hill of the OSIRIS-REx education and public outreach program. "Amateur astronomers may have to make what are called 'track and stack' observations," a technique that acquires and adds multiple short images.

"One of the major goals of having amateur astronomers on board is they can observe these objects every night, unlike professional astronomers who may get to telescopes once every few nights, or more typically once a month or every three months," Hergenrother said.

People don't need to own their own telescopes or live under clear skies to work on Target Asteroids!, Hergenrother and Hill emphasized.

For not much money, observers can now go online and sign up to use a growing network of quality robotic telescopes sited at some of the choicest astronomical spots in the country, they added.

Scientists will compare data from amateur and professional astronomers' ground-based observations with data from OSIRIS-REx spacecraft instruments to learn more about Earth-crossing asteroids and identify likely candidates for future asteroid missions, they said.

"The OSIRIS-REx mission truly is a 'ground truth' mission, the connection between meteorites on the ground and asteroids that are still orbiting the sun that could hit the ground," Hill said.

Not long ago, astronomers disparaged asteroids as the "vermin of the skies," said Ed Beshore, OSIRIS-REx deputy principal investigator. Astronomers saw asteroids as bothersome "noise," unwanted streaks of light that contaminated their photographic views of celestial objects farther out in the cosmos.

That thinking changed when people realized how much damage near-Earth asteroids can do when they hit Earth as meteorites, Beshore said.

For example, sophisticated mathematical modeling shows that the chunk of meteorite that blasted 1.25-kilometer-wide Meteor Crater out of northern Arizona's Colorado Plateau about 50,000 years ago was less than 70 meters wide. Granted, that space rock was a rare iron-nickel meteorite that carried a much greater wallop than a stony or carbonaceous meteorite of the same size would have had. But still, that's impressive.

Until Beshore was named OSIRIS-REx deputy principal investigator earlier this year, he directed the University of Arizona's Catalina Sky Survey. This NASA-funded survey has led the world in searching for potentially hazardous NEOs, or near-Earth objects, since 2005. Amateur astronomers have helped enormously by providing follow-up observations that find orbits of newly discovered asteroids, Beshore said.

"Amateur astronomy today is much different than it was, say, even in the mid-1990s," Beshore said. "The amateur astronomy community working now is extremely sophisticated. They have more advanced computers. They have developed a tremendous number of turnkey solutions to automate their telescopes. And they now can rent telescopes larger than most amateurs can afford.

"You've got a lot of dedicated amateurs out there who really are working like professionals, making serious contributions to the field," he said.

"Frankly, if they wanted to, many could probably get jobs as professionals. But they're probably making more money doing what they're doing at their day jobs."

Target Asteroids! partner organizations so far include:

    * The International Astronomical Search Collaboration, or IASC, http://iasc.hsutx.edu/ . The IASC is an educational outreach program that provides free, donated telescope time to amateur astronomers from 30 high schools and colleges in five countries for asteroid observations. Students in the United States and Poland are already analyzing results on one of the Target Asteroids! that IASC members made using a 1.3-meter telescope at Kitt Peak National Observatory near Tucson last February, Hill said.
    * Astronomical League, http://www.astroleague.org/ . An umbrella organization of about 140 amateur astronomy organizations across the United States. Based in Kansas City, Mo., it promotes astronomy by encouraging public interest via local astronomy clubs.
    * Association of Lunar & Planetary Observers, http://alpo-astronomy.org/ Founded in 1947, this organization facilitates research by both professional and amateur astronomers working in lunar, planetary and solar astronomy. Members and section coordinators are scattered all over the world.
    * Oceanside Photo and Telescope, or OPT, http://www.optcorp.com/edu One of the largest telescope retailers in the world, based in Oceanside, Calif., OPT provides technical expertise and astronomy equipment to educators and organizations across the country.
    * NASA Night Sky Network, http://nightsky.jpl.nasa.gov A nationwide coalition of amateur astronomy clubs that provide information about NASA missions and host astronomy events for the general public. The Night Sky Network is sponsored and supported by the NASA Jet Propulsion Laboratory's "PlanetQuest" program.
    * University of Arizona Mt. Lemmon SkyCenter, http://skycenter.arizona.edu This University of Arizona science center is located where astronomical seeing is outstanding, at the 9,200-foot summit of Mount Lemmon in the Santa Catalina Mountains north of Tucson. It offers both nightly public astronomy programs and opportunities for remote observing using the 32-inch Schulman telescope and 24-inch Beshore telescope. The SkyCenter is a partner in the Sierra Stars Observing Network, http://www.sierrastars.com , a widening network of professional observatories working to make advanced imaging capabilities available to amateur astronomers at modest cost.
    * The Catalina Sky Survey, University of Arizona Lunar and Planetary Laboratory, http://www.lpl.arizona.edu/css The Catalina Sky Survey has been the most successful near-Earth object survey for several years running. This survey discovered 586 near-Earth asteroids, or 65 percent of all NEO discoveries made in 2011. In fall 2008, CSS scientists became the first to observe an asteroid on a collision course with the Earth, allowing that object to be tracked and eventually recovered as meteorites in the Sudan's Nubian Desert.

Click here to visit the Target Asteroids! webpage.

Click here to read the official NASA press release.

Contact Hergenrother and Hill for more information about Target Asteroids! by e-mail to Target_Asteroids@lpl.arizona.edu .


Все смотрим в космос
ЦитатаС сегодняшнего дня под эгидой NASA разворачивается проект по поиску околоземных объектов - астероидов, изредка проходящих близко к Земле. Астрономы-любители помогут лучше изучить свойства популяции астероидов, их скорость вращения и изменения в отражательной способности. Астрономы-профессионалы затем используют эти данные  для улучшения моделей таких объектов, в число которых входит астероид 1999 RQ36. Во многом с ним связан новый проект, он должен помочь в подготовке аппарата OSIRIS-Rex.


ASC's 3D Flash LIDAR camera selected for OSIRIS-REx asteroid mission
May 13th, 2012 by Chris Bergin

The Advanced Scientific Concepts (ASC) 3D Flash LIDAR (Light Detection And Ranging) range cameras have been selected for the OSIRIS-REx planetary science mission that will return a sample of the carbonaceous asteroid 1999 RQ36. The mission - launching in 2016 - is aiming to return the asteroid sample to Earth in 2023.



Asteroid Nudged by Sunlight: Most Precise Measurement of Yarkovsky Effect
ЦитатаScientists on NASA's asteroid sample return mission, Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx), have measured the orbit of their destination asteroid, 1999 RQ36, with such accuracy they were able to directly measure the drift resulting from a subtle but important force called the Yarkovsky effect - the slight push created when the asteroid absorbs sunlight and re-emits that energy as heat.

"The new orbit for the half-kilometer (one-third mile) diameter 1999 RQ36 is the most precise asteroid orbit ever obtained," said OSIRIS-REx team member Steven Chesley of the NASA Jet Propulsion Laboratory, Pasadena, Calif. He presented the findings May 19 at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan.

These series of radar images of asteroid 1999 RQ36 were obtained by NASA's Deep Space Network antenna in Goldstone, Calif. on Sept 23, 1999. (Credit: NASA/JPL-Caltech)

Observations that Michael Nolan at Arecibo Observatory in Puerto Rico made in September 2011, along with Arecibo and Goldstone radar observations made in 1999 and 2005, when 1999 RQ36 passed much closer to Earth, show that the asteroid has deviated from its gravity-ruled orbit by roughly 100 miles, or 160 kilometers, in the last 12 years, a deviation caused by the Yarkovsky effect.

The Yarkovsky effect is named for the nineteenth-century Russian engineer who first proposed the idea that a small rocky space object would, over long periods of time, be noticeably nudged in its orbit by the slight push created when it absorbs sunlight and then re-emits that energy as heat.

"The Yarkovsky force on 1999 RQ36 at its peak, when the asteroid is nearest the sun, is only about a half ounce - about the weight of three grapes on Earth. Meanwhile, the mass of the asteroid is estimated to be about 68 million tons. You need extremely precise measurements over a fairly long time span to see something so slight acting on something so huge."

Nolan and his team measured the distance between the Arecibo Observatory and 1999 RQ36 to an accuracy of 300 meters, or about a fifth of a mile, when the asteroid was 30 million kilometers, or 20 million miles, from Earth.

"That's like measuring the distance between New York City and Los Angeles to an accuracy of two inches, and fine enough that we have to take the size of the asteroid and of Arecibo Observatory into account when making the measurements," Nolan said.

Chesley and his colleagues used the new Arecibo measurements to calculate a series of 1999 RQ36 approaches closer to Earth than 7.5 million kilometers (4.6 million miles) from the years 1654 to 2135. There turned out to be 11 such encounters.

By combining the radar results from Arecibo Observatory with infrared results from NASA's Spitzer Space Telescope, the scientists also learned that asteroid 1999 RQ36 is very light - it has around the same density as water, Chesley reported.

"This study is an important step in better understanding the Yarkovsky effect -- a subtle force that contributes to the orbital evolution of new Near-Earth Objects," said Dante Lauretta, the mission's principal investigator and professor of planetary science at the University of Arizona.

Lauretta added that "this information is critical for assessing the likelihood of an impact from our target asteroid and provides important constraints on its mass and density, allowing us to substantially improve our mission design."

The OSIRIS-REx spacecraft is to launch in 2016, reach asteroid (101955) 1999 RQ36 in 2019, examine it up close during a 505-day rendezvous, then return at least 60 grams (~1.9 ounces) of it to Earth in 2023.

"In addition to the exciting Yarkovsky results, the low density shows that 1999 RQ36 is probably a loose aggregate of rocks--a so called rubble pile," said Jason Dworkin, the mission's project scientist and Chief of Astrochemistry at NASA's Goddard Space Flight Center in Greenbelt, Md. "This makes it an ideal target for OSIRIS-REx to collect loose surface material."

NASA's Goddard is responsible for overall mission management for the OSIRIS-REx project. The Lunar and Planetary Laboratory at the University of Arizona in Tucson leads the science mission. Lockheed Martin Space Systems in Denver will build and operate the spacecraft. OSIRIS-REx is the third mission in NASA's New Frontiers Program. NASA's Marshall Space Flight Center in Huntsville, Ala., manages New Frontiers for the agency's Science Mission Directorate in Washington.

For more information about the OSIRIS-REx mission, visit: http://osiris-rex.lpl.arizona.edu/


NASA Scientist Figures Way to Weigh Space Rock

This computer generated image of asteroid 1999 RQ36 was derived from data acquired by the NASA-supported Arecibo Observatory in Puerto Rico. Image credit: NASA/NSF/Cornell/Nolan

A scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., has accurately determined the mass of a nearby asteroid from millions of miles away. The celestial equivalent of "guess your weight" was achieved by Steve Chesley of JPL's Near-Earth Object Program Office by utilizing data from three NASA assets - the Goldstone Solar System Radar in the California desert, the orbiting Spitzer Space telescope, and the NASA-sponsored Arecibo Observatory in Puerto Rico.

Chesley presented his findings this past Saturday, May 19, at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan.

For Chesley to define the asteroid's mass, he first needed to understand its orbit and everything that could affect that orbit -- including neighboring celestial bodies and any propulsive force (however minute) the asteroid could generate.

Incorporating extraordinarily precise observations collected by astronomer Michael Nolan at Arecibo Observatory in September 2011, Arecibo and Goldstone radar observations made in 1999 and 2005, and the gravitational effects of the sun, moon, planets and other asteroids, Chesley was able to calculate how far the asteroid deviated from its anticipated orbit. He found that 1999 RQ36 had deviated from the mathematical model by about 100 miles (160 kilometers) in the past 12 years. The only logical explanation for this orbital change was that the space rock itself was generating a minute propulsive force known in space rock circles as the Yarkovsky effect.

The Yarkovsky effect is named for the 19th-century Russian engineer who first proposed the idea that a small, rocky space object would, over long periods of time, be noticeably nudged in its orbit by the slight push created when it absorbs sunlight and then re-emits that energy as heat. The effect is hard to measure because it's so infinitesimally small.

"At its peak, when the asteroid is nearest the sun, the Yarkovsky force on 1999 RQ36 is only about a half ounce -- around the weight of three grapes," said Chesley. "When you're talking about the force of three grapes pushing something with a mass of millions of tons, it takes a lot of high-precision measurements over a long time to see any orbital changes. Fortunately, the Arecibo Observatory provided a dozen years of great radar data, and we were able to see it."

The final piece to the puzzle was provided by Josh Emery of the University of Tennessee, Knoxville, who used NASA's Spitzer Space Telescope in 2007 to study the space rock's thermal characteristics. Emery's measurements of the infrared emissions from 1999 RQ36 allowed him to derive the object's temperatures. From there he was able to determine the degree to which the asteroid is covered by an insulating blanket of fine material, which is a key factor for the Yarkovsky effect.

With the asteroid's orbit, size, thermal properties and propulsive force (Yarkovsky effect) understood, Chesley was able to perform the space rock scientist equivalent of solving for "X" and calculate its bulk density.

"While 1999 RQ36 weighs in at about 60 million metric tons, it is about a half kilometer across," said Chesley. "That means it has about the same density as water, so it's more than likely a very porous jumble of rocks and dust."

Asteroid 1999 RQ36 is of particular interest to NASA as it is the target of the agency's OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) mission. Scheduled for launch in 2016, ORIRIS-Rex will visit 1999 RQ36, collect samples from the asteroid and return them to Earth.

NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and establishes their orbits to determine if any could be potentially hazardous to our planet. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. JPL also manages the Spitzer Space Telescope and Goldstone Solar System Radar.

More information about asteroids and near-Earth objects is at: http://www.jpl.nasa.gov/asteroidwatch .


ЦитатаЕвропа вообще должна быть целью номер 1. Но сначала срезали Европу Орбитер, потом JIMO теперь и с Лапласом непонятки. Что то странное. А метеорного вещества и на земле валом и Хаябуса со Стардастом привезли. И Хаябуса-2 намечается.

Мне кажется, что все-таки Титан. Есть атмосфера, позволяющая находится там без скафандра, нет радиации как на Европе.


Без скафандра...? А температуру атмосферы знаете? :D


ЦитатаБез скафандра...? А температуру атмосферы знаете? :D

Это уже не такой скафандр. В моём понимании вообще не скафандр. Не тот, что несколько миллионов$  стоит  :D


ЦитатаAsteroid Nudged by Sunlight: Most Precise Measurement of Yarkovsky Effect
Как сильно Солнце подталкивает астероиды?
ЦитатаИсследователям НАСА удалось с беспрецедентной точностью измерить, с какой силой эффект Ярковского влияет на траекторию астероида. Точное предсказание конкретного влияния может иметь ключевое значение для нашей осведомлённости о потенциально опасных для Земли небесных телах.

При подготовке миссии OSIRIS-REx группе исследователей НАСА пришлось максимально точно вычислить орбиту астероида 1999 RQ36 и определить влияние на неё различных сил, в том числе эффекта Ярковского -- дрейфа астероида под действием светового давления светила и последующей отдачи тепла в космос (когда нагретая сторона небесного тела отворачивается от Солнца).

Выяснилось, что 1999 RQ36, диаметром в 0,5 км, за 12 лет наблюдений (со дня своего открытия) изменил орбиту под действием эффекта Ярковского на 160 км. Что неожиданно много: если бы мы следили за этим телом 12 млн лет, его орбита изменилась бы на 160 млн км.

Эти данные очень значимы в свете того, что, по некоторым моделям, Земля систематически захватывает в качестве временных астероиды по 100 и более км в диаметре, часть из которых потом падает на её поверхность. Естественно, человечеству требуется некоторое время для реализации защитных мероприятий в случае осуществления такого сценария. Однако раньше долговременный расчёт орбиты астероида был невозможен: слишком большое влияние на неё оказывал эффект Ярковского. Земные же инструменты были не слишком точны. В итоге «правильных» предсказаний орбит этих небезопасных для нас небесных тел на срок, превышающий «несколько лет», просто не существовало.

Теперь, похоже, ситуация может измениться. Авторы работы представили результаты своих наблюдений на встрече, посвящённой астероидам, кометам и метеорам, которая прошла в Ниигате (Япония).

Ранние трудности в измерении эффекта Ярковского были вызваны его малой величиной; так, в случае 1999 RQ36 приданная им тяга эквивалентна 0,15 Н. «Это примерно равно весу трёх виноградин на Земле, в то время как масса астероида оценивается в 68 млн тонн. Нужны экстремально точные измерения, проводимые приличное время, чтобы увидеть нечто столь медленно и слабо воздействующее на такое внушительное тело», -- отмечает Майкл Нолан из обсерватории Аресибо в Пуэрто-Рико, один из участников исследования. К примеру, дистанцию от Земли до астероида надо было измерить с точностью до одной стомиллионной, то есть ошибка не должна превышать 300 м, и это при удалении от небесного тела в 30 млн км.

Так вот, выяснилось, что в период между 1654 и 2135 годом астероид приближался к Земле на 7,5 млн км, а общее число сближений за 500 лет составляет 11 раз. Средняя плотность астероида оказалась необычной -- примерно равной плотности воды в земных условиях.

Информация по орбите и плотности 1999 RQ36 принципиальна для подготовки миссии OSIRIS-REx, предназначенной для доставки с астероида грунта. Проект был выбран на конкурсной основе по НАСА-программе «Новые рубежи» (New Frontiers). OSIRIS-REx стартует в 2016 году, в 2019-м аппарат нагонит астероид и заберёт с него образцы грунта (скорее всего, пыли и льда), а к 2023 году вернётся на Землю.


Согласно www.lpi.usra.edu/pss/may2012/presentations/1Green_PSS_status.pdf запуск планируется в сентябре 2016




NASA Announces Asteroid Naming Contest for Students

НАСА предложило школьникам придумать название для астероида
ЦитатаМОСКВА, 4 сен - РИА Новости. Американское аэрокосмическое агентство НАСА объявило конкурс среди школьников всего мира на лучшее название для астероида 1999 RQ36, куда в 2016 году отправится зонд OSIRIS-REx для того, что бы с помощью манипулятора собрать образцы с его поверхности, а затем доставить их на Землю.

Участники конкурса, которыми могут стать школьники из любой страны мира младше 18 лет, должны до 2 декабря 2012 года представить жюри название астероида (длиной не более 16 букв), а также краткое объяснение этого названия и обоснование своего выбора.

"Мы с нетерпением ждем, когда мы получим имя, которое будет легче произнести, чем 1999 RQ36", - говорит Данте Лауретта (Dante Lauretta), научный руководитель миссии OSIRIS-REx.

Первый приз конкурса получит школьник, чей вариант названия для астероида будет принят Комитетом по названиям малых тел Солнечной системы Международного астрономического союза.

Астероид (101955) 1999 RQ36 был открыт в 1999 году участниками проекта LINEAR (Lincoln Near Earth Asteroid Research) в лаборатории Линкольна Массачусетского технологического института. Размер этого небесного тела составляет около 500 метров. Астероид богат углеродом, ключевым элементом для всех органических молекул. Такие молекулы ранее находили в метеоритах и образцах с комет. Ученые рассчитывают выяснить, есть ли такие вещества на RQ36.

Американский "астероидный проект" под названием OSIRIS-REx (Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer - "происхождение - спектральная интерпретация - обнаружение ресурсов - безопасность - исследователь реголита") был выбран из числа трех других программ, в числе которых были программа по доставке образцов с обратной стороны Луны и миссия по исследованию поверхности Венеры.

Для США это будет первая программа исследования астероида с помощью автоматического зонда, ранее такой проект успешно осуществила Япония: стартовавший в 2003 году зонд "Хаябуса" совершил посадку на астероид Итокава, а в середине июня 2010 года капсула зонда приземлилась в австралийской пустыне, в ней были обнаружены частицы вещества астероида.

Аппарат приблизится к астероиду 1999 RQ36 к 2020 году. Оставаясь в пяти километрах от астероида OSIRIS-REx в течение шести месяцев будет тщательно картировать поверхность небесного тела, после чего ученые смогут выбрать место, откуда с помощью будет взят образец вещества массой около 60 граммов. Затем он будет помещен в капсулу, которая, как ожидается, совершит посадку на полигоне в штате Юта в 2023 году.


ЦитатаДля США это будет первая программа исследования астероида с помощью автоматического зонда, ранее такой проект успешно осуществила Япония: стартовавший в 2003 году зонд "Хаябуса" совершил посадку на астероид Итокава, а в середине июня 2010 года капсула зонда приземлилась в австралийской пустыне, в ней были обнаружены частицы вещества астероида.


Видео (Lockheed Martin)

Asteroids and the OSIRIS-REx Mission



Американское аэрокосмическое агентство (НАСА) планирует отправить к астероиду 1999 RQ36 в 2018 году зонд OSIRIS-REx, который измерит силу так называемого эффекта Ярковского -- сдвига орбиты астероида в результате нагрева одной из его сторон Солнцем, что позволит точно оценить их опасность для Земли, сообщает пресс-служба агентства.

"К примеру, солнечная сторона кирпичного здания остается теплой даже в поздние вечерние часы, так как она в это время излучает тепло, накопленное за день. Аналогичным образом астероиды излучают тепло на своей "вечерней" стороне, в результате чего создается слабая реактивная тяга, "сталкивающая" небесное тело с его орбиты", -- пояснил руководитель проекта OSIRIS-REx Эдвард Бешор (Edward Beshore) из университета Аризоны в Тусоне (США).

Эффект Ярковского, наряду с гравитационным взаимодействием Земли и пролетающих мимо ее астероидов, считается одной из причин того, почему на нашу планету упало гораздо больше небесных тел, чем на то указывают расчеты. Точная оценка силы этого эффекта необходима для понимания того, как меняются орбиты астероидов, и какую опасность наши ближайшие "соседи", такие как Апофис (2004 MN4) или микроастероид 2012 DA14, могут нести для жизни на Земле.

Как утверждают специалисты НАСА, силу эффекта Ярковского из-за его небольшой мощности практически невозможно измерить при помощи наземных инструментов. По этой причине НАСА планирует запустить в 2018 новый зонд OSIRIS-REx, который отправится к астероиду 1999 RQ36 и проследит за изменениями в скорости движения этого небесного тела и в его орбите, которые произойдут благодаря эффекту Ярковского.

Первоначальной целью данного аппарата, запуск которого был ранее намечен на 2016 год, является картографирование астероида и забор пробы грунта, которую OSIRIS-REx попытается доставить обратно на Землю. Как полагают астрономы, замеры силы эффекта Ярковского и фрагменты 1999 RQ36 помогут им разработать алгоритм, который позволит определять, как будут меняться орбиты других астероидов в результате "подогрева" Солнцем.


09.02.2013 13:07:02 #38 Последнее редактирование: 09.02.2013 12:07:24 от instml
Цитатаscream пишет:
Американское аэрокосмическое агентство (НАСА) планирует отправить к астероиду 1999 RQ36 в 2018 году зонд OSIRIS-REx, который измерит силу так называемого эффекта Ярковского -- сдвига орбиты астероида в результате нагрева одной из его сторон Солнцем, что позволит точно оценить их опасность для Земли, сообщает пресс-служба агентства.
Запуск в 2018 - бредятина, откуда они такое взяли? Журноламеры фиговы.

Scheduled for launch in 2016, OSIRIS-REx will arrive at RQ36 in 2018 and orbit the asteroid until 2021. By communicating continuously with a spacecraft in orbit around RQ36, the team will get a much better idea of the asteroid's orbit.


New NASA Mission to Help Us Better Estimate Asteroid Impact Hazard




Every year, sensors designed to detect nuclear explosions see harmless bursts in Earth's upper atmosphere fr om the breakup of an asteroid a few yards across. Tiny asteroids are much more numerous than big ones, so destructive hits to Earth are very rare. However, because of their potential for devastation, NASA's Near-Earth Object (NEO) observations program supports surveys which are undertaking sustained searches to find the largest objects and predict their impact threat to Earth.
 According to NASA's NEO program, there are more than 1,300 "Potentially Hazardous Asteroids" (PHAs) - objects at least 150 yards (about 140 meters) across with a very small chance of impacting us someday because their orbital paths take them close to Earth's orbit.
 "Asteroids move at an average of 12 to 15 kilometers per second (about 27,000 to 33,000 miles per hour) relative to Earth, so fast that they carry enormous energy by virtue of their velocity," says Edward Beshore of the University of Arizona, Tucson, deputy principal investigator for NASA's OSIRIS-REx asteroid sample return mission. "Anything over a few hundred yards across that appears to be on a collision course with Earth is very worrisome."
 The main difficulty is obtaining sufficient observations to be able to predict their orbits with enough certainty to find out if they could hit us at some point.
 "When an asteroid makes a close pass to Earth, the gravitational pull fr om our planet changes the asteroid's orbit," says Beshore. "However, how this change will affect the evolution of the asteroid's orbit is difficult for us to predict because there are also other small forces continuously acting on the asteroid to change its orbit. The most significant of these smaller forces is the Yarkovsky effect - a minute push on an asteroid that happens when it is warmed up by the sun and then later re-radiates this heat in a different direction as infrared radiation."
 The Yarkovsky effect happens simply because it takes time for things to heat up and cool down. Objects tend to be coldest just before dawn and warmest at mid-afternoon, after hours of illumination by the high sun. "A brick building can feel warm even in the early evening hours, because it is radiating away the heat accumulated from an entire day of sunshine," says Beshore. In the same way, an asteroid radiates most of its heat from its late "afternoon side", giving it the small Yarkovsky push which is variable depending mostly on the asteroid's size, shape and composition.
 NASA's OSIRIS-REx mission (Origins, Spectral Interpretation, Resource Identification, Security, and Regolith Explorer) will make the most precise measurements of the Yarkovsky effect to date by visiting a PHA called "1999 RQ36" or just "RQ36."

"For such a large object, it has one of the highest known probabilities of impacting Earth, a 1 in 2,400 chance late in the 22nd century, according to calculations by Steve Chesley, an astronomer at NASA's Jet Propulsion Laboratory," said Beshore. RQ36 is about 457 meters (500 yards) across.
 The best measurements of the Yarkovsky effect are made when an asteroid's position is precisely known. "If an asteroid comes very close, we can get radar observations on it," says Beshore. "With radar measurements, we get very good data on its range and therefore can constrain one aspect of its orbit very well. If we can get that measurement a couple of times (or more) over a few years, it helps us understand its orbital behavior and we can start to make an estimate of the Yarkovsky effect. We estimate the position of the asteroid and what its orbit must be like by using Newtonian and Relativistic physics. If we see a deviation from the estimated position, then it must be due to the sum of all these other small forces, and the greatest of these we believe to be the Yarkovsky effect."
 Measurements like these enabled the team to estimate the very small force of the Yarkovsky effect on RQ36 - about equal to the weight felt when holding three grapes, according to Beshore. "Although very small, this force is constant and adds up over time to significantly change the asteroid's orbit," adds Beshore.
 Scheduled for launch in 2016, OSIRIS-REx will arrive at RQ36 in 2018 and orbit the asteroid until 2021. By communicating continuously with a spacecraft in orbit around RQ36, the team will get a much better idea of the asteroid's orbit.
 "We expect OSIRIS-REx will enable us to make an estimate of the Yarkovsky force on RQ36 at least twice as precise as what's available now," says Jason Dworkin, OSIRIS-REx project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

The team will use what it learns about the Yarkovsky effect on RQ36 to help estimate the effects on other asteroids. "What we want to be able to do is create a model that says okay if you give me an asteroid of this size, made of this composition, with this kind of topography, I can estimate for you what the Yarkovsky effect will be," says Beshore. "So now I can probably come up with a better notion of what to expect from other asteroids that I don't have the good fortune to have a spacecraft around."
 Given that OSIRIS-REx lets us better model the Yarkovsky effect, and we discover an asteroid that might hit us someday, what if anything can be done about it?
 "There are several mitigation strategies," says Beshore. "We could explode a small nuclear device close above the surface on one side of the asteroid. This could be very effective - it would vaporize the surface layer, which would then fly off at very high speed, causing a rocket thrust that would shove everything over by a few centimeters per second. This might be plenty to deflect the asteroid. Other strategies include kinetic impactors, wh ere you strike an asteroid very hard with a heavy projectile moving at high speed. In 2005, NASA's Deep Impact mission hit comet Tempel 1 with a 370-kilogram (over 815-pound) copper slug at about five kilometers per second (over 11,000 miles per hour), not nearly enough to significantly alter the orbit of the five-kilometer-sized body, but a proof of the technology for this kind of mission. Another idea is to use a gravity tractor - station a spacecraft precisely enough near the asteroid which would gradually deflect it with only its gravitational pull."
 The key to all these strategies is to discover the asteroid well in advance of its impact date and attempt to deflect it early, according to Beshore. "If you're trying to deflect an arrow, you wouldn't need to apply much force to the arrow to make it widely miss the target if you could deflect it as it left the bow," says Beshore. "On the other hand, if you had to deflect it right before it hit the target, you'd need to push on it a whole lot more to get it out of the way."
 One of the first things that would be done if an asteroid appeared to be on a collision course with Earth is to send a probe to the asteroid that might look very much like OSIRIS-REx, according to Beshore. "You want to characterize it first to choose the correct deflection strategy," says Beshore. "For example, we know the density of RQ36 is about 1 gram per cubic centimeter, over two times less than solid rock. This means it is probably a rubble pile - a collection of boulders, rocks, and dust loosely held together by gravity. Some deflection strategies might be ineffective with this kind of asteroid."
 OSIRIS-REx will determine if RQ36 is actually a rubble pile by orbiting it and revealing the subtle effects on the orbit from the gravity of any large and dense lumps within the asteroid. A probe like OSIRIS-REx could map the internal structure of an asteroid this way, providing valuable information on wh ere to target the deflection mechanism.

OSIRIS-REx will also determine the composition of RQ36 using remote measurements from both visible light and infrared spectrometers, and by collecting a sample of material from the asteroid's surface and returning it to Earth for study. Since the Yarkovsky effect may vary depending on the type of material and its distribution, a probe with OSIRIS-REx's capability to map the surface composition will enable a more precise estimate of the Yarkovsky effect on the asteroid's orbit.
 The mission will also provide critical experience navigating around asteroids. "We don't have a lot of experience doing precise maneuvers near one of these objects with very small gravity," says Beshore. "It's not easy to stay in orbit around it - this asteroid's gravitational pull is so weak, the push from sunlight on our spacecraft's solar panels will be roughly similar to the amount of force from the gravity of RQ36 itself. We have to factor in a lot of these forces to navigate and operate around an asteroid. With OSIRIS-REx, we'll generate a set of techniques and technologies for any mission that would go to an asteroid to characterize it in advance of a mitigation mission."
 The OSIRIS-REx mission is led by Principal Investigator Dante Lauretta of the University of Arizona, supported by a science team of Co-Investigators from multiple institutions, with project management at NASA's Goddard Space Flight Center, Greenbelt, Md., and development partnership with Lockheed Martin Space Systems, Littleton, Colo. International contributions are provided by the Canadian Space Agency. The OSIRIS-REx mission was selected under the NASA New Frontiers program, managed by NASA's Marshall Space Flight Center, Huntsville, Ala., and funded by NASA's Science Mission Directorate, NASA Headquarters, Washington.
 › More information about OSIRIS-REx