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By Guest Blogger, Nathan Edge This month Nathan Edge discusses the nature and operation of nuclear devices being used in unmanned space operations. As an aside, I can't believe I wasn't the first person to type into Google, "nuclear engine...USS Enterprise"?! Nathan provides links to sites for more information throughout the piece. Anyway, on with the article!-------------------------------------------------Nuclear power isn’t just applicable to terrestrial electricity generation; it has also been used in space travel since 1961 – whereby it is still a tremendous source of potential for propulsion mechanisms. Many well known space vehicles such as the deep space probes Voyagers 1 & 2 – which are over 18,000,000,000 and 15,000,000,000 km from Earth respectively – rely on nuclear power. It is even being used on NASA’s Curiosity Rover, which made a spectacular touchdown on Mars last year.Voyager 2. One of the most distant man-made objects in existence.The popularised spacecraft don’t actually use conventional nuclear reactors. Radioisotope thermoelectric generators (RTGs) - which harness Plutonium-238 as fuel - are the primary propulsion source. These so-called “nuclear batteries” exploit the principle that plutonium undergoes alpha-decay to produce heat. This is subsequently converted in to electricity using thermoelectric generators. Since they have no moving parts, RTGs are very reliable; the RTG on Voyager 2 has worked continuously since 1977, and is expected to continue working until 2025.A general RTG configurationThis is not to say, however, traditional nuclear reactors have not also been used in space operations in the past … albeit with some serious modifications. For example, the Soviet RORSAT satellites used 90% enriched uranium fuel as a power source. The safety implications of using such a system in earth orbit are obvious, and any fears of utilising such a technology are not exactly unfounded. The nuclear-powered Cosmos 954 satellite, for instance, fell into Canada in 1978 after a systems failure, distributing radioactive debris over 124,000 square kilometres. Due to events like these, it is likely that any future reactors will be confined to deep space like RTGs. However, this does not mean that they will only be used for unmanned exploration probes. NASA has its eyes on a manned Mars mission, but traditional chemical rockets would take six to seven months to reach Mars. A 1MW fission reactor powering 100-400 kW electric ion thrusters would take 3 months, thus limiting the health degradation astronauts face on long space journeys.Modern RTGs are designed to survive the possible accidents which could befall it during operation, including propellant fires during launch and land/water impacts. Reassuringly, RTGs cannot explode like nuclear weapons: the plutonium associated with weapons is Pu-239, not Pu-238. A similar safety feature which has been specified for nuclear reactor propulsion tech is that they are not activated until they are confirmed to have reached space successfully. Ultimately, this is to ensure fission fragments and other components of nuclear waste are not present if failure occurs during launch. Space: The future of waste disposal?Lastly, when using an RTG some additional thought must be applied to the disposal of the spacecraft when they come to the end of their working life. This is not just a nuclear issue: it’s important not to disturb any areas which potentially harbour extraterrestrial life. For example the RTG-powered Galileo spacecraft was sent into Jupiter’s atmosphere and destroyed to stop it crashing into a potential ocean under Europa’s crust. The disposal of RTGs and future nuclear reactors actually touch on one of the more outlandish proposals for dealing with nuclear waste: firing it out of the solar system.In short, the space and nuclear industry have a surprising legacy: nuclear power has already been used successfully for near-earth and deep space missions in the past, and its use has continued into the cutting edge-missions of today. Only time will tell whether or not it is the key to future exploration, both manned and unmanned, into our universe.DOCUMENT LINKS (IN ORDER OF APPEARANCE)NASA, 2013 Where are the Voyagers? [online]. Available at: http://voyager.jpl.nasa.gov/where/index.html[Accessed 02/02/2013]Atmos, J. 2012. Curiosity rover made near-perfect landing [online]. Available at: http://www.bbc.co.uk/news/science-environment-19219782[Accessed 02/02/2013]Snyder, G.J. Small Thermoelectric Generators [pdf]. Available at: http://www.electrochem.org/dl/interface/fal/fal08/fal08_p54-56.pdf[Accessed 02/02/2013]NASA, 2013. Voyager – Spacecraft Lifetime [online].Available at: http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html[Accessed 03/02/2013]Encyclopaedia of Science, 2013. RORSAT (Radar Ocean Reconnaissance Satellite [online]. Available at: http://www.daviddarling.info/encyclopedia/R/RORSAT.html[Accessed 03/02/2013]HackCanada, 2013. Cosmos 954 Satellite Crash [online]. Available at: http://www.hackcanada.com/canadian/other/cosmos954.html[Accessed 10/02/2013]King, L, 2012. Manned Mars mission still on track [online]. Available at: http://usatoday30.usatoday.com/tech/story/2012/09/12/manned-mars-mission-still-on-track/57767950/1[Accessed 11/02/2013]Rousseau, I.M. 2007. Analysis of a High Temperature Supercritical Brayton Cycle for Space Exploration [pdf]. Available at: http://web.mit.edu/rsi/www/pdfs/papers/2005/2005-ianr.pdf[Accessed 01/10/2012]Discovery, 2013. Known effects of long-term space flights on the human body [online]. Available at: http://www.racetomars.ca/mars/article_effects.jsp[Accessed 10/02/2013].US Department of Energy, 1982. Nuclear Safety Criteria and Specifications for Space Nuclear Reactors [pdf]. Available at: http://www.fas.org/nuke/space/osnp-1.pdf[Accessed 20/02/2013].NASA, 2013. Solar system exploration  -Galileo Legacy Site [online]. Available at: http://solarsystem.nasa.gov/galileo/[Accessed 21/02/2013].The Space Review, 2013. Nuclear waste in space? [online]. Available at: http://www.thespacereview.com/article/437/1[Accessed 22/02/2013]IMAGESSpace Today Online, 2011. Voyagers are leaving the Solar System [online]. Available at: http://www.spacetoday.org/SolSys/Voyagers20years.html[Accessed 02/02/2013].Wikipedia, Radioisotope thermoelectric generator [online]. Available at: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator[Accessed 02/02/2013]Gunter’s Space Page, 2013. US-A[online]. Available at: http://space.skyrocket.de/doc_sdat/us-a.htm[Accessed 05/02/2013]The Space Review, 2013. Nuclear waste in space? [online]. Available at: http://www.thespacereview.com/article/437/1[Accessed 22/02/2013]

Florida’s Native and Non-Native Sword Fernsby: Lara Miller, Natural Resource AgentJennifer Jones, Brooker Creek Preserve InternFlorida is home to many native fern species, including the Boston fern (Nephrolepis exalta) and giant sword fern (Nephrolepis biserrata), which can be difficult to distinguish from non-native ferns that grow in the same environments, such as Tuberous sword fern (Nephrolepis cordifolia) and the Asian sword fern (Nephrolepis multiflora). Each of these are often still sold in the nursery and landscape trade, and often confused or misidentified as the native species of fern. The NativesThe native Boston fern (Figure 1) has erect fronds that can reach up to 3 feet long and 6 inches wide. The round sori (clusters of spore-bearing organs) are in two rows near the underside of the pinnae (leaflet). It is commonly found in humid forests and swamps of Florida, although is native to other regions such as South and Central America. It is grown outdoors as well as indoors for ornamental value; their high humidity tolerance makes them a good candidate for both indoor and outdoor use. Figure 1. Native Boston FernThe native giant sword fern (Figure 2) has fronds that extend several feet and can be found in moist to wet soil. The species name comes from tiny teeth that alternate with larger teeth along the edge of each lance-like pinna. Underneath each pinna, round sori occur evenly around the entire edge. The petioles (stalk) are sparse to moderate with reddish to light brown hair-like scales. Tubers are never present in this species.Figure 2. Native Giant Sword FernThe Non-NativesSince the non-native ferns can be invasive and disruptive to native plant communities, it is very beneficial to be able to recognize the differences between them. The Asian sword fern and Tuberous sword fern are sold under various names, often ones of native origin. Tuberous sword fern (Figure 3) sometimes produces tubers, and it is the only one of the four ferns mentioned that is capable of doing so. The presence of these tubers alone is a distinct way to identify the species. The presence of scales on the upper side of the rachis (stem) that is distinctively darker at the point of attachment is another way to distinguish the tuberous sword fern from the other three species. Native sword fern has scales on the upper side and are homogenously colored. Figure 3. Non-Native Tuberous Sword FernTuberous sword fern can be distinguished from Asian sword fern (Figure 4) by its glabrous central vein of the pinnae contrasted by the presence of short stiff hairs that occur on the central vein of the pinnae of Asian and giant sword fern. The most distinguishing characteristic for Asian sword fern is a dense covering of dark brown, pressed scales with pale margins on mature petioles. Petiole scales of tuberous sword fern are dense, spreading, and pale brown, while those of native sword fern are sparse to moderate, reddish-brown, of a single color or slightly darkened at the point of attachment and have expanded bases with small hairs. Figure 4. Non-Native Asian Sword FernResources:http://www.floridata.com/ref/n/neph_exa.cfmhttp://edis.ifas.ufl.edu/uw217http://edis.ifas.ufl.edu/pdffiles/AG/AG12000.pdf

Join us this week as we walk through the book of Galatians exploring our freedom in Christ. 30:34 minutes (14 MB)

Click Here to ListenShow Notes: http://www.alumnipodcast.com/In this episode I talk with John Hill of the Michigan State Alumni Association. John is responsible for directing the Alumni Career Services office at MSU and is a leader in the field.We talk about how John and his team took a passive, you-come-to-us type program and turned it into program delivery machine. In addition, he explains the Life stage model to Alumni Career Services and how that is a generator of alumni giving. Finally he talks about how LinkedIn and Twitter are integral components to their strategy.Resources:· http://msualum.com/careers/· Find John on Twitter at @msuaajohn· Send him email at hilljohn@msu.eduSend me feedback to paul.clifford@alumnipodcast.com or feedback@alumnipodcast.com. Please leave comments below or on the iTunes Music store.

From shorts to features, fiction films to documentaries, directing to acting, Werner Herzog (Fitzcarraldo, Aguirre, The Wrath of God, Grizzly Man, Rescue Dawn) has completely immersed himself in film. His newest is his take on Bad Lieutenant. He talks about his own approach to film and life.