• 快讯 Gas vs. solid phase deuterated chemistry

    来源专题:中国科学院紫金山天文台科技信息监测服务
    编译者:pmosy
    发布时间:2017-05-16
    The formation of deuterated molecules is favoured at low temperatures and high densities. Therefore, the deuteration fraction D$_{frac}$ is expected to be enhanced in cold, dense prestellar cores and to decrease after protostellar birth. Previous studies have shown that the deuterated forms of species such as N2H+ (formed in the gas phase) and CH3OH (formed on grain surfaces) can be used as evolutionary indicators and to constrain their dominant formation processes and time-scales. Formaldehyde (H2CO) and its deuterated forms can be produced both in the gas phase and on grain surfaces. However, the relative importance of these two chemical pathways is unclear. Comparison of the deuteration fraction of H2CO with respect to that of N2H+, NH3 and CH3OH can help us to understand its formation processes and time-scales. With the new SEPIA Band 5 receiver on APEX, we have observed the J=3-2 rotational lines of HDCO and D2CO at 193 GHz and 175 GHz toward three massive star forming regions hosting objects at different evolutionary stages: two High-mass Starless Cores (HMSC), two High-mass Protostellar Objects (HMPOs), and one Ultracompact HII region (UCHII). By using previously obtained H2CO J=3-2 data, the deuteration fractions HDCO/H2CO and D2CO/HDCO are estimated. Our observations show that singly-deuterated H2CO is detected toward all sources and that the deuteration fraction of H2CO increases from the HMSC to the HMPO phase and then sharply decreases in the latest evolutionary stage (UCHII). The doubly-deuterated form of H2CO is detected only in the earlier evolutionary stages with D2CO/H2CO showing a pattern that is qualitatively consistent with that of HDCO/H2CO, within current uncertainties. Our initial results show that H2CO may display a similar D$_{frac}$ pattern as that of CH3OH in massive young stellar objects. This finding suggests that solid state reactions dominate its formation. .
  • 快讯 Bigelow Aerospace and ULA to announce new partnership

    来源专题:中国科学院紫金山天文台科技信息监测服务
    编译者:zhoubz
    发布时间:2016-04-12
    This artist’s concept depicts the Bigelow Expandable Activity Module (BEAM), constructed by Bigelow Aerospace, attached to the International Space Station (ISS). Image Credit: Bigelow Aerospace Expandable space habitat manufacturer Bigelow Aerospace and launch provider United launch Alliance (ULA) issued a press release on Friday stating that the two companies would announce a new partnership at a news conference on Monday, April 11, at 4 p.m. MDT, at the 32nd Space Symposium in Colorado Springs Colorado. Both ULA CEO Tony Bruno and Bigelow Founder and President Robert Bigelow will be at the press conference which will be live-streamed on ULA’s website. The announcement comes just as a crucial on-orbit test of expandable habitat technology is about to begin. Expandable habitats are lighter and require less payload volume than traditional rigid structures. After being deployed in space, they can provide a comfortable area for astronauts to live and work inside. The habitats can also provide varying degrees of protection from solar and cosmic radiation, space debris, ultraviolet radiation and other conditions in space that are potentially harmful to humans. Image Credit: Bigelow Aerospace On Sunday, April 10, Bigelow’s Expandable Activity Module (BEAM) will arrive at the International Space Station (ISS) in the unpressurized aft trunk of SpaceX’s CRS-8 Dragon spacecraft. Five days later, the module will be removed and attached to the station using the station’s Canadarm2 robotic arm. Expansion of the module to its full size of 10 feet in diameter and 13 feet in length is scheduled to begin in late May. BEAM’s mass is approximately 3,000 pounds (1,360 kg). It consists of two metal bulkheads, an aluminum structure, and multiple layers of a Kevlar-like material, with spacing between the layers. BEAM should remain attached to the space station for about two years. During this time, ISS crew members will enter the module for a few hours several times a year to retrieve data from sensors and to assess how it is handling the rigors of space flight. It is hoped that this demonstration mission will help NASA to determine how well the habitat protects crews against solar radiation, space debris, and contamination. At the end of the two-year testing and evaluation period, astronauts will use the space station’s robotic arm again; this time, to detach BEAM from the orbiting lab. The module will then de-orbit and burn up during its descent through Earth’s atmosphere. Bigelow plans to produce a much larger habitat module in the future. The B330 is planned to be some 57 feet (17.3 meters) long and have 330 cubic meters (12,000 cubic feet) of usable internal space. The module is capable of providing living quarters for up to 6 astronauts and has an estimated lifespan of 20 years. B330 modules could be used for a number of purposes including orbital space stations, habitation modules for deep-space exploration, or surface habitats on the Moon or Mars. B330 habitats could be launched into space by the 552 variant of ULA’s Atlas V booster.
  • 快讯 Dragon ‘caught’ at International Space Station

    来源专题:中国科学院紫金山天文台科技信息监测服务
    编译者:zhoubz
    发布时间:2016-04-12
    April 10th, 2016 An archive photo of a previous Dragon berthed at the International Space Station. Photo Credit: NASA Two days after a textbook launch, SpaceX’s CRS-8 Dragon cargo ship rendezvoused and was berthed to the International Space Station (ISS). Capture by the space station’s robotic Canadarm2 took place at 6:23 a.m. CDT (11:23 GMT) April 10 about 250 miles (402 kilometers) above the Pacific Ocean just west of Hawaii. Controlling the arm was Expedition 47 Flight Engineer and European Space Agency (ESA) astronaut Tim Peake. He, along with NASA astronaut Jeff Williams, monitored the approaching vessel from the Cupola window. A Falcon 9 launched with the CRS-8 Dragon at 4:43 p.m. EDT (20:43 GMT) April 8 from Cape Canaveral Air Force Station’s Launch Complex 40. Photo Credit: Michael Howard / SpaceFlight Insider “It looks like we caught a Dragon,” Peake said after capture. Then, over the next two hours, ground teams controlled the arm to move Dragon from its capture point just 33 feet (10 meters) below the station to the Earth-facing port of the Harmony module. The command to automatically drive four bolts in the Common Berthing Mechanism connecting Dragon and Harmony was given at about 8:55 a.m. CDT (13:55 GMT). The stations computer rejected the command at first, but upon trying a second time, it accepted and the spacecraft was officially berthed to the ISS at 8:57 a.m. CDT (13:57 GMT)—some 40 feet (12 meters) from the OA-6 Cygnus cargo ship attached to the Unity module. This marks the first time two commercial vehicles were at the station at the same time. Dragon arrived just outside the station’s “Keep-out Sphere”—an area of about 656 feet (200 meters) around ISS—about 30 minutes later than originally planned. This was due to greater than expected atmospheric drag on the spacecraft’s solar panels resulting in correction burns by the vehicle’s Draco thrusters. The cargo ship reached the 820-foot (250-meter) hold point at about 5 a.m. CDT (10:00 GMT). This allowed for verification that the spacecraft had established a two-way UHF communications link with the space station. Flight controllers reduced the amount of time at this hold point, and a little over five minutes later, the spacecraft resumed its careful approach to the orbiting outpost. About 30 minutes later, Dragon was 98 feet (30 meters) from ISS. Ground teams in Houston and SpaceX headquarters in Hawthorne, California, were polled to verify everything was still “GO” for final approach and capture. Additionally, Williams could evaluate the ship to verify it was in the correction position and issue a hold, abort, or retreat in the event of a problem. However, everything was nominal and the approach continued until Dragon was just 33 feet (10 meters) below the Destiny lab. At 6:22 a.m. CDT (11:22 GMT) Peake manually controlled the arm to the grapple fixture on Dragon. A minute later, contact was made. The arrival of Dragon marked only the second time in the history of the space station program that six vehicles were docked or berthed to the outpost. The last time was in 2011 when Space Shuttle Discovery was docked with the complex on mission STS-133—that orbiter’s final flight. That was also the only time all of the originally planned government-owned vehicles (Space Shuttle, Soyuz, Progress, Japanese HTV, and the European Space Agency’s ATV) were at the station at the same time. This is the eighth Dragon to visit the space station—the first since the ill-fated CRS-7 mission. It is also the 84th uncrewed cargo ship and 170th overall mission to reach the orbiting laboratory. The hatch between the cargo ship and space station will be opened early Monday morning. In the next three weeks, Dragon’s 7,000 pounds (3,175 kilograms) of food, supplies, and experiments will be unloaded and dispersed throughout ISS. Additionally, the vessel will be reloaded with trash and unneeded equipment to be returned to Earth. On April 16, CRS-8’s most notable cargo, the Bigelow Expandable Activity Module (BEAM) will be robotically removed from the unpressurized trunk of the spacecraft and attached to the aft port of the Tranquility module. It will be expanded sometime in late May. Dragon is expected to remain attached to the space station until May 1 of this year (2016).
  • 快讯 Euclid to probe dark universe with Astrium science module

    来源专题:中国科学院紫金山天文台科技信息监测服务
    编译者:zhoubz
    发布时间:2016-04-12
    11 June 2013The module carrying the telescope and scientific instruments of ESA’s Euclid ‘dark Universe’ mission is now being developed by Astrium in Toulouse, France. Euclid will be launched in 2020 to explore dark energy and dark matter in order to understand the evolution of the Universe since the Big Bang and, in particular, its present accelerating expansion. Dark matter is invisible to our normal telescopes but acts through gravity to play a vital role in forming galaxies and slowing the expansion of the Universe. Dark energy, however, causes a force that is overcoming gravity and accelerating the expansion seen around us today. Together, these two components are thought to comprise 95% of the mass and energy of the Universe, with ‘normal’ matter, from which stars, planets and we humans are made, making up the remaining small fraction. Their nature remains a profound mystery. “Euclid will address the cosmology-themed questions of ESA’s Cosmic Vision 2015–25 programme with advanced payload technologies, enabling Europe to become a world leader in this field of research,” says Thomas Passvogel, Head of the Project Department in ESA’s Directorate of Science and Robotic Exploration. Astrium will deliver a fully integrated payload module incorporating a 1.2 m-diameter telescope feeding the mission’s two science instruments, which are being developed by the Euclid Consortium. The two state-of-the art, wide-field instruments – a visible-light camera and a near-infrared camera/spectrometer – will map the 3D distribution of up to two billion galaxies and the associated dark matter and dark energy, spread over more than a third of the whole sky. By surveying galaxies stretched across ten billion light-years, the mission will plot the evolution of the very fabric of the Universe and the structures within it over three-quarters of its history. In particular, Euclid will address one of the most important questions in modern cosmology: why is the Universe expanding at an accelerating rate today, rather than slowing down due to the gravitational attraction of all the matter in it? The discovery of this cosmic acceleration in 1998 was rewarded with the Nobel Prize for Physics in 2011 and yet there is no accepted explanation for it. By using Euclid to study its effects on the galaxies and clusters of galaxies across the Universe, astronomers hope to come much closer to understanding the true nature and influence of this mysterious dark energy. “We are excited that Euclid has reached this important milestone, allowing us to progress towards launch in 2020, and bringing us ever closer to uncovering some of the Universe’s darkest secrets,” says Giuseppe Racca, ESA’s Euclid Project Manager. Notes for Editors. Euclid is an ESA survey mission to investigate the nature of dark matter and dark energy. It was selected as the second Medium-class mission in ESA’s Cosmic Vision programme in October 2011 and formally adopted in June 2012. The mission will be launched in 2020 and will orbit around the Sun–Earth L2 point located 1.5 million km from Earth. Science and spacecraft operations will be conducted by ESA. More than 1000 scientists from over 100 institutes form the Euclid Consortium building the instruments and participating in the scientific harvest of the mission. The consortium comprises scientists from 13 European countries: Austria, Denmark, France, Finland, Germany, Italy, the Netherlands, Norway, Portugal, Romania, Spain, Switzerland and the UK. It also includes a number of US scientists, including 40 nominated by NASA.
  • 快讯 Heavyweight: ‘S.S. Rick Husband’ ferries Cygnus’ heaviest payload to date with OA-6

    来源专题:中国科学院紫金山天文台科技信息监测服务
    编译者:zhoubz
    发布时间:2016-04-12
    An Atlas V 401 rocket, carrying Orbital ATK’s S.S. Rick Husband Cygnus spacecraft, flies from Space Launch Complex 41at 11:05 p.m. EDT (03:05 GMT on Wednesday, March 23) with the OA-6 cargo resupply mission to the International Space Station. Photo Credit: Jacques van Oene / SpaceFlight Insider CAPE CANAVERAL, Fla. — A ULA Atlas V rocket, in the 401 configuration, caused windows to rattle and car alarms to go off for miles around the Space Coast as the booster and S.S. Rick Husband Cygnus spacecraft ferried an estimated 7,756 lbs (3,518 kg) of cargo on its way to the International Space Station – the largest payload the spacecraft has sent aloft so far. Orbital ATK and United Launch Alliance sent the fifth mission – under the $1.9 billion Commercial Resupply Services contract Orbital ATK has with NASA – on its way in spectacular fashion in the late evening hours of Tuesday, March 22. This was the second, and final, planned launch of the Cygnus spacecraft atop a ULA Atlas V 401 rocket from Cape Canaveral. Photo Credit: Jared Haworth / We Report Space The mission got underway promptly at 11:05 a.m. EDT (03:05 GMT), at the very opening of a 30-minute launch window. The weather conditions at the Cape simply could not have been more ideal. Mostly clear skies and a light breeze welcomed the Atlas V and its precious cargo as the rocket left the launch pad and slowly climbed into the moonlit skies above SLC-41. “Today’s successful launch continues our great progress and momentum under the CRS contract with NASA,” Frank Culbertson, President of Orbital ATK’s Space Systems Group said via a release issued by the company. “I applaud the numerous professionals at NASA, ULA and Orbital ATK for their hard work and dedication. While we are still early in this mission, everything is tracking well. We now eagerly await Cygnus’ berthing with the ISS and conducting scientific experiments onboard the spacecraft for the first time.” Forecasts had predicted a 90 percent chance of favorable launch conditions – by liftoff, it was clear that those conditions had reached 100 percent. Chilly temps had crept into the area yesterday, with highs only reaching the mid-60s during the day. That trend continued throughout today. As noted, Tuesday’s launch was watched over by a full Moon, the light from which was unfettered by a smattering of clouds. While concerns about cumulus clouds had been raised, the Launch Readiness Review cleared the Atlas V booster to be rolled from the adjacent Vertical Integration Facility (VIF) to SLC-41 on Monday, March 21, with the booster traversing the short distance between the two structures starting at 10 a.m. EDT (14:00 GMT). The cargo for this mission included an array of science experiments. Technology demonstrators such as Gecko Grippers to look into how artificial gecko setae (the hairs on the small reptiles’ feet) could aid robots sent on orbit or to distant planetary destinations. The Additive Manufacturing Facility or “AMF” is being launched on behalf of California-based Made in Space to serve as a permanent platform at the space station from which to print parts, experiments, and other needed items that would otherwise require a separate launch to get to orbit. Strata-1, meanwhile, will focus more on the physical locations that astronauts might be sent to such as an asteroid, the Moon, and Mars. Various regolith simulators will help researchers gain a better understanding of how actual regolith behaves in the microgravity environment. After about 55 days, with its cargo transferred to the ISS and it has been unberthed from the orbiting laboratory, Cygnus will spend an additional eight days on orbit. During this time, scientists will conduct the Saffire-1 experiment. Contained within its own compartment and away from the used experiments, waste, and trash that the Expedition 47 and 48 crews will have loaded the Cygnus spacecraft with, the experiment will ignite the largest purposely-set fire on orbit that has been lit today. It is hoped the experiment will provide a better understanding of flame propagation on orbit. The Atlas V booster is well-suited to handle sending Cygnus to orbit as the rocket is described as having the ability to send some to 21,600 lbs (9,800 kg) low-Earth orbit and 10,470 lbs (4,479 kg) to a geostationary transfer orbit. The rocket was launched for the first time on Aug. 31, 2002; the 401 configuration of the rocket has flown 31 times since then. The March 22 launch was greeted by a full Moon. Photo Credit: Michael Seeley / We Report Space Shortly after it left the pad, the Atlas V booster conducted a pitch, yaw, and roll maneuver so as to maintain the correct ascent profile as well as to minimize aerodynamic loads on the vehicle. One minute and twenty-three seconds into the flight Atlas was traveling Mach 1 – the speed of sound. Eleven seconds later and the vehicle entered the region of maximum dynamic pressure or “max-Q”. At this part of the flight, the rocket’s speed along with the density of the atmosphere conspired with one another to place the rocket and its precious cargo under the greatest amount of stress. At booster engine cutoff (BECO), the RD-180 was burning its fuel of RP-1 (a highly refined form of kerosene) and liquid oxygen at the impressive rate of about 1,350 lbs per second – and moving at a speed of 10,000 miles (16,093 kilometers) per hour. At this point in the flight, the rocket and payload were some 80 miles in altitude (Atlas was about 170 miles down range). Four-and-a-quarter minutes after it had left the pad at SLC-41, Booster Engine Cutoff took place, with separation between the first stage and the Centaur upper stage taking place about six seconds after that. A little more than four-and-a-half minutes into the flight, the first burn of the Centaur upper stage (MES-1) took place. The burn lasted approximately 37 seconds, ending at 18 minutes and nine seconds after liftoff. Having completed its primary mission of shielding Cygnus through Earth’s atmosphere, the Payload Fairing or “PLF” was jettisoned some eight seconds later. About a second-and-a-half under 21 minutes after it had left the pad far below, the S.S. Rick Husband separated from Centaur, unfurled its two solar arrays and began the final leg of its journey to the ISS. “This was our second mission on an Atlas V rocket after our very successful OA-4 mission which we launched last December,” Orbital ATK’s Vice President of Advanced Programs in the Space Systems Group at Orbital ATK, Frank DeMauro told SpaceFlight Insider. “The Cygnus team has been very busy with both tonight’s mission, as well as the return-to-flight on Antares for this summer, 2016.”