Угроза из космоса.13 октября 2014 года произошло нечто очень странное с камерой…



Угроза из космоса.

13 октября 2014 года произошло нечто очень странное с камерой LROC на борту зонда Lunar Reconnaissance Orbiter. Обычно она получает красивые четкие изображения лунной поверхности, однако в тот раз снимок получился сильно искаженным. Команда ученых определила, что камера, судя по всему, испытала столкновение с крошечным метеоритом!

На самом деле у зонда не одна камера, а целая система из трех: две узкоугольных камеры получают черно-белые изображения высокого разрешения, а третья широкоугольная камера получает снимки менее высокого разрешения, однако обладает набором фильтров, для определения свойств и цветовой гаммы поверхности Луны.

Инцидент произошел при работе одной из узкоугольных камер. Предполагается, что искажения на фото – результат резкого, кратковременного и сильного колебания камеры в поперечном направлении. При этом во время съемки не было никаких событий, таких как движение солнечных батарей или антенн, которые могли бы вызвать такие колебания, а камера была полностью исправна и перед запуском в космос успешно прошла вибрационные тесты. Команда исследователей построила компьютерную модель и пришла к выводу, что искажения, обнаруженные на снимке от 13 октября, вызваны попаданием метеороида, размером около 0,8 мм, двигавшегося со скоростью около 7 километров в секунду, с ориентировочной плотностью хондритового метеорита (2,7 г / см3). Сейчас камера функционирует исправно, столкновение не нанесло ей вреда.

Оригинал на английском: https://www.nasa.gov/feature/goddard/2017/camera-on-nasas-lunar-orbiter-survived-2014-meteoroid-hit

Star Forming Filaments

A false-color image map of the gas density in the Musca star-forming filament (the highest densities are shown in red). New theoretical work on the structure of these long filaments proposes several kinds of star-forming zones along the length and successfully reproduces many of the features seen in filaments like this one in Musca. Credit: Kainulainen, 2016

Interstellar molecular clouds are often seen to be elongated and “filamentary” in shape, and come in a wide range of sizes. In molecular clouds, where stars form, the filamentary structure is thought to play an important role in star formation as the matter collapses to form protostars. Filamentary clouds are detected because the dust they contain obscures the optical light of background stars while emitting at infrared and submillimeter wavelengths. Observations of some filaments indicate that they are themselves composed of bundles of closely spaced fibers with distinct physical properties.
Computer simulations are able to reproduce some of these filamentary structures, and astronomers generally agree that turbulence in the gas combined with gravitational collapse can lead to filaments and protostars within them, but the exact ways in which filaments form, make stars, and finally dissipate are not understood. The number of new stars that develop, for example, varies widely between filaments for reasons that are not known.
The usual model for a star forming filament is a cylinder whose density increases towards the axis according to a specific profile, but which otherwise is uniform along its length. CfA astronomer Phil Myers has developed a variant of this model in which the filament has a star-forming zone along its length where the density and diameter are higher, with three generic profiles to describe their shapes. Besides being a more realistic description of a filament’s structure, the different density profiles develop different strength gravitational “wells” naturally leading to different numbers of stars forming within them.
Myers compares the star formation properties of these three kinds of zones with the properties of observed star formation filaments, with excellent results. The filament in the molecular cloud in Musca has relatively little star formation, and can be reasonably well explained with one of the three profiles indicative of an early stage of evolution. A small cluster of young stars in the Corona Australis constellation fits a second model that has evolved for longer, while Ophiuchus hosts a filament that may be near the end of its star forming lifetime and resembles the third type. The three profiles so far seem able to account for the full range of conditions. The new results are an important step in bringing more sophistication and realism to the theory of star forming filaments. Future work will probe the specific processes that fragment the various star-forming zones into their stars.

Reference(s): 
“Star-forming Filament Models,” Philip C. Myers, ApJ 838, 10, 2017.

Source Astronomy Cmarchesin

“DARPA COMMISSIONS BOEING TO BUILD A HYPERSONIC…

“DARPA COMMISSIONS BOEING TO BUILD A HYPERSONIC SPACEPLANE”

 DARPA has announced that it has selected Boeing to design and build a new reusable, hypersonic spaceplane called the Phantom Express which will be capable of flying into high suborbital altitudes to launch satellites into orbit before landing back on Earth horizontally like an airplane.
 Unlike the Air Force’s X-37B unmanned spaceplane that launches on top of an Atlas V rocket, the Phantom Express, also known as XS-1, will launch vertically on its own internal engines using cryogenic propellants – liquid oxygen and liquid hydrogen – reminiscently like the old space shuttles. This spaceplane, at the size of about a business jet, would fly at hypersonic speeds over Mach 5 to reach suborbital altitudes before releasing its satellite-launching second stage.
 “Phantom Express is designed to disrupt and transform the satellite launch process as we know it today, creating a new, on-demand space-launch capability that can be achieved more affordably and with less risk,“ said Darryl Davis, president of Boeing Phantom Works, in a press release. If the program is successful, DARPA predicts the XS-q could operate with costs under $5 million per launch (which is considered very cheap in the rocket market).

Read more about this fascinating story at: http://www.popularmechanics.com/military/aviation/a26628/darpa-boeing-build-hypersonic-spaceplane/