Wilson C.F.,University of Oxford |
Chassefiere E.,University Paris - Sud |
Hinglais E.,French National Center for Space Studies |
Baines K.H.,NASA |
And 21 more authors.
Experimental Astronomy | Year: 2012
The European Venus Explorer (EVE) mission described in this paper was proposed in December 2010 to ESA as an 'M-class' mission under the Cosmic Vision programme. It consists of a single balloon platform floating in the middle of the main convective cloud layer of Venus at an altitude of 55 km, where temperatures and pressures are benign (~25°C and ~0. 5 bar). The balloon float lifetime would be at least 10 Earth days, long enough to guarantee at least one full circumnavigation of the planet. This offers an ideal platform for the two main science goals of the mission: study of the current climate through detailed characterization of cloud-level atmosphere, and investigation of the formation and evolution of Venus, through careful measurement of noble gas isotopic abundances. These investigations would provide key data for comparative planetology of terrestrial planets in our solar system and beyond. © 2011 Springer Science+Business Media B.V.
Ehrenfreund P.,Leiden Institute of Chemistry |
Ehrenfreund P.,Space Policy Institute |
Ulamec S.,German Aerospace Center |
Barucci M.A.,LESIA Observatoire de Paris |
And 9 more authors.
Proceedings of the International Astronautical Congress, IAC | Year: 2012
MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) selected in February 2011 for the Assessment Study Phase in the framework of ESA's Cosmic Vision 2 program. MarcoPolo-R is a European mission and takes advantage of three completed industrial studies. MarcoPolo-R will rendezvous with a unique kind of target, the primitive binary NEA (175706) 1996 FG3. The MarcoPolo mission will scientifically characterize the binary NEA system at multiple scales, and return a unique pristine sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. The binary target provides enhanced science return: precise measurements of the mutual orbit and rotation state of both components can be used to probe higher-level harmonics of the gravitational potential, and therefore the internal structure. The main goal of the MarcoPolo-R mission is to return unaltered NEA material for detailed analysis in ground-based laboratories which will allow scientists to study the most primitive materials available to investigate early Solar System formation processes. Copyright © (2012) by the International Astronautical Federation.
Amelia Trainer can recite the Seamus Heaney poem, “Scaffolding,” by memory. It starts: Masons, when they start upon a building, Are careful to test out the scaffolding; Make sure that planks won't slip at busy points, Secure all ladders, tighten bolted joints. Trainer, a sophomore majoring in physics and nuclear science and engineering, calls “Scaffolding” “probably the most true and meaningful love poem I’ve read.” But its metaphorical take on a relationship might also resonate for Trainer around her work with the Computational Reactor Physics Group (CRPG), where Trainer is deeply committed to learning about strengthening structures in a nuclear realm. Since early in her freshman year, Trainer has been part of a team helping refine OpenMC Monte Carlo, a powerful computational code for modeling neutron behavior inside nuclear reactors. Developed by the CRPG, with support from the U.S. Department of Energy, OpenMC offers the possibility of “simulations that recreate the world inside a reactor,” Trainer says. “This means we can make operating reactors safer, improve future designs, and avoid doing costly experiments. It’s the coolest thing ever.” Her engagement with this research has already earned recognition: She won an outstanding Undergraduate Research Opportunity Project (UROP) award, and presented a paper to the American Nuclear Society Student Conference in 2015, all based on work she performed in freshman year. In OpenMC simulations, scientists are interested in testing a variety of reactor parameters, including operating temperature. But it can be time-consuming to generate simulation data for a large number of nuclides at specific temperatures, and research suggested it might be possible to achieve comparably accurate results by instead interpolating between specific temperatures. Trainer’s research tested this hypothesis by comparing different interpolation models with actual experiments. “Instead of generating data for nuclear material at 293 kelvins, we could say the data roughly equals some material at 250 K and some at 300 K while preserving accuracy,” Trainer says. “We can save time with a shortcut like this, and make everyone’s life easier.” Trainer got a running start on this project. “I began pestering Jon Walsh [a PhD candidate working in the CRPG group under the direction of professors Kord Smith and Benoit Forget] with emails looking for a research project before freshman orientation,” she says. “I can’t emphasize how much I like this project and the research group as a whole.” Given her avid interest in this work, and her double major, it is somewhat surprising to learn that as late as the summer before senior year in high school Trainer was uncertain about attending college. In her Florida high school, some students didn’t bother, and Trainer, while a top scholar and math team member, was happy serving up ice cream at a beach shop. “I enjoyed food service,” she says. “I had a million things in my head to think about and I got paid for a job that left my mind free to wander all day.” But Trainer soon shifted course. She’d had a revelation in physics class: “The most excited I’d been in high school was when a teacher described how nuclear reactors worked, what E=mc2 is, and I thought I should learn more about this stuff.” She also won a scholarship to Embry-Riddle Aeronautical University to learn computer coding, and discovered she had a knack for programming. Then, after a friend in a fantasy basketball league suggested she was accomplished enough to attend college, Trainer decided to apply to MIT. Today, not even halfway through her undergraduate career, Trainer believes she has found her calling: “I’m very happy with what I’m working on now,” she says. “Why change a good thing?” Her software writing proficiency has proved essential: She interned at Los Alamos National Laboratory last summer as a code developer, one of only a few undergraduates in her division. Coding is also central to her current CRPG research, which involves processing giant data libraries generated by the national laboratories into compact versions whose parameters are used by CRPG codes for the purposes of performing reactor simulations. She is also comparing U.S. data libraries to those of other countries, which are based on different assumptions and experiments. At this point, Trainer says she would like nothing better than to pursue an academic career “just trying slowly to add to the bank of what people understand about nuclear energy, furthering computational tools.” She would be especially pleased to do this at MIT. “I have an opportunity to be at the forefront, studying under the most brilliant minds, and if I don’t take advantage of this, I’d be completely missing out,” Trainer says.
The frenetic dance of neutrons inside a nuclear reactor generates heat and produces electricity. Reactor physicist Lulu Li wants to make sense of this kinetic choreography, with the ultimate goal, she says, of “making nuclear reactors safer, more reliable, and economical to operate.” A fourth-year doctoral student and member of the Computational Reactor Physics Group (CRPG) in MIT's Department of Nuclear Science and Engineering (NSE), Li is developing precise and detailed simulations of neutron behavior that could have a major impact on current and future generations of nuclear reactors. Under the direction of NSE professors and faculty advisors Kord Smith and Benoit Forget, Li has created a new method for accelerating the solution of neutron-transport equations — mathematical characterizations of the movements made by neutrons in time and space from the moment the first atom of nuclear fuel undergoes fission. “We want to know how many neutrons there are, where they’re going, and with what energy and velocity,” says Li. Li and her colleagues’ mathematical simulations are intended to reduce uncertainties in nuclear plants, which must operate within strict safety limits. More accurate models of neutron behavior will give plant designers a better way of characterizing the safety limits of current and new designs, thus improving fuel efficiency and operations. “The better we understand things inside, the more economic value we can get out of a reactor,” says Li. While equations have long existed for modeling neutrons, recent advances in computing power now make possible much faster fine-grained mathematical simulations. “Supercomputers enable us to develop methods that were not previously possible to execute, and to accomplish them in a reasonable timeframe,” says Li. With two other graduate students, Li created a new modeling platform, called the open-source method of characteristics neutron-transport code (OpenMOC), which was published in the Annals of Nuclear Energy last June. She presented research related to this platform at the U.S. Department of Energy’s Consortium for Advanced Simulation of Light Wave Reactors, where she won the best poster award at its 2014 workshop. Li’s interest in devising algorithms for accelerating reactor simulations emerged after a summer internship in 2009 following her sophomore year at Rhodes College in Tennessee. A physics major, she applied for an internship with MIT’s Department of Nuclear Science and Engineering. “Back then, I confused nuclear engineering and nuclear physics, so I came here with the wrong assumption.” It turned out to be a happy mistake for Li. “People in the department here were extremely friendly, and taught me stuff from scratch,” she recounts. “I knew how to perform tasks on the computer, but nothing about theory, and over the summer they helped me catch up.” Li also met the research group she works with now, which led to a second internship the following summer. “They were amazing mentors, passionate and really patient with me. That’s what ultimately helped me decide what to do.” Li completed her undergraduate education in physics at the University of Illinois at Urbana-Champaign, where she found a calling in computational programming. “I tried the experimental stuff, but realized I was no good at it,” she says. “I was never a hands-on person.” During a childhood attempt to add physical memory to a computer, Li recalls smoke billowing from the machine. “I went into mathematical simulations because you don’t have anything to break, and with the computer, you can undo any previous versions of your work,” says Li. “It totally fits who I am.” For her dissertation, Li is harnessing supercomputers to model neutron behavior in full-scale nuclear reactors. Her algorithms are intended to predict with high fidelity the behavior of individual neutrons caroming off the tiny pellets of fissile fuel material that comprise nuclear-fuel assemblies. With novel reactor concepts under development and the rising costs of experimental facilities, Li’s algorithms aid the analysis and optimization of designs at a very fundamental level. After she receives her PhD, Li is aiming for a job with industry, where she hopes to put her computations to use with the current fleet of light-water reactors, and next-generation plants as well. “I’d like to inform people who develop new reactors,” she says. “Simulation is the first-stage test bed that opens up a design space.”
Srama R.,University of Stuttgart |
Srama R.,Max Planck Institute for Nuclear Physics |
Kruger H.,Max Planck Institute for Solar System Research |
Yamaguchi T.,Japan Aerospace Exploration Agency |
And 65 more authors.
Experimental Astronomy | Year: 2012
The Stardust mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this mission have changed our view and knowledge on the early solar nebula. The Rosetta mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for the first time in great detail the comet nucleus and its environment starting in 2014. Additional astronomy and planetary space missions will further contribute to our understanding of dust generation, evolution and destruction in interstellar and interplanetary space and provide constraints on solar system formation and processes that led to the origin of life on Earth. One of these missions, SARIM-PLUS, will provide a unique perspective by measuring interplanetary and interstellar dust with high accuracy and sensitivity in our inner solar system between 1 and 2 AU. SARIM-PLUS employs latest in-situ techniques for a full characterisation of individual micrometeoroids (flux, mass, charge, trajectory, composition) and collects and returns these samples to Earth for a detailed analysis. The opportunity to visit again the target comet of the Rosetta mission 67P/Churyumov-Gerasimeenternko, and to investigate its dusty environment six years after Rosetta with complementary methods is unique and strongly enhances and supports the scientific exploration of this target and the entire Rosetta mission. Launch opportunities are in 2020 with a backup window starting early 2026. The comet encounter occurs in September 2021 and the reentry takes place in early 2024. An encounter speed of 6 km/s ensures comparable results to the Stardust mission. © 2012 Springer Science+Business Media B.V.