MILWAUKEE — As Cactus League play drew to an end and the Giants prepared to travel north to round out their exhibition schedule, they hadn’t settled on a starting center fielder for 2018.Back in March, the Giants had practically penciled in their Opening Day center fielder for 2019, but the team’s top decision-makers struggled to determine whether Steven Duggar was ready to play in the major leagues right away.Days before the season began, Duggar learned he would open the year at Triple-A …
South Africa’s Sumbandila satellite undergoing vacuum chamber tests at Houwteq, the Denel Aerospace Division facility near Grabouw in the Western Cape. (Image: SunSpace) The SunSpace pioneers: CEO Bart Cilliers, executive chairperson Themba Vilakazi, and Ron Olivier. (Image: SunSpace) Small machine, big technology: the Sumbandila satellite. (Image: SunSpace)Jennifer SternAt the rate technology develops, the impossible becomes possible, the improbable happens daily, and things which were once the province of the technical elite become commonplace.Take satellites, for example. The Russians launched Sputnik, the first satellite, into earth orbit only 50 years ago, but now there are more than 25 000 satellites estimated to be circling the globe – some 16 000 of them inoperative space junk.And – here is the surprising part – not all of those were built by big government programmes with multibillion-dollar budgets. Three of those little specks of matter up there were made in a small laboratory outside Cape Town.It all started in 1992 when Garth Milne, Jan du Plessis, Sias Mostert and the late Arnold Schoonwinkel of Stellenbosch University’s Department of Electrical and Electronic Engineering initiated a postgraduate programme to build a satellite.Using a modular construction designed by Surrey Satellite Systems Technology (SSTL) and spending the modest sum of about R11-million (US$1.4-million) over seven years, the student group produced their first satellite in 1999. It was called Sunsat – a contraction of Stellenbosch University satellite.Off-the-shelf componentsWhereas most satellites are usually manufactured from specially designed and built components by companies well entrenched in the space programme, SSTL set out to prove that it was possible to build a satellite from commercially available off-the-shelf components. And Stellenbosch piggybacked on their findings.As with many great endeavours, the first thing most people ask is “Why?” In the case of Sunsat, the answer is not the usual “Because we can,” but the more accurate “To prove we can” – and to prove it without access to the specialised technology that is the preserve of the space programme elites. An equally important aim was to train students in satellite technology, because there’s no better way to learn than to do.Building it was the main objective, but it would always have had a cloud hanging over it (instead of the other way round) if it never got to fly. So the Sunsat group were delighted to get a payload from Nasa – flying a magnetometer and GPS testing programme. With the help of the Hermanus Magnetic Observatory about an hour east of Cape Town, the Sunsat team designed a magnetometer that could fit inside the tiny 600mm by 600mm by 900mm satellite.On 23 February 1999 the 64kg satellite was loaded aboard an American-designed Delta 7926 rocket launcher at Van den Bergh Air Force Base in the US, and blasted into a low level sun-synchronous orbit.Nasa worked out that they needed six months to collect sufficient data for their purposes, and estimated that Sunsat would keep going for about 11 months, so they figured they were safe. But they got more than they bargained for. Sunsat just missed being functional for its second birthday, being bashed out of its orbit by a rogue bit of rocket booster on 22 January 2000.Nasa got a bargain. And so did Sunsat, as launching satellites is not exactly cheap, at about $25 000 (R205 100) per kilogram. Luckily, Nasa picked up the tab on this one.So Sunsat was an unmitigated success. It flew, it did its job, and it lasted more than twice as long as predicted. More importantly, it contributed immensely to the development of high-tech expertise, its main purpose.Going commercialBut a good thing tends to generate an energy all of its own. After Sunsat’s successful launch, the team was approached in 2000 by a party who, for business and strategic reasons, remains nameless. The client was looking for a platform for “earth imaging remote sensing equipment” – satellite imagery, in English.This created a conflict, as the team was part of the university, set up to do research and teaching – not to fulfil commercial contracts for foreign customers. So they started a company called SunSpace, and moved off campus to Techno Park, a few kilometres down the road. This satellite was much bigger than Sunsat, weighing in at about 200kg.Construction was started in late 2000, and it was delivered in March 2003, but only launched in May 2007. It is still floating about up there, taking photographs of the earth. Even before this satellite was delivered, the client ordered another higher-spec one, which is already under construction. When completed, this will be the fourth satellite built by the group that is now SunSpace.The pathfinderIf you’ve been counting, you’ll notice there is a gap. The third satellite, which is called Sumbandila, was built for the South African government. The name is a Venda word that means “clear the way” or “pathfinder.”Ordered in December 2005, the completed satellite was delivered in December 2006, taking only 12 months to build. It was to be launched from a Russian submarine in the Bering Sea in late December 2006 or early January 2007. But that didn’t happen, and Sumbandila remains sadly earthbound – a depressing state of affairs for an ambitious satellite. And ambitious this project is. It was designed to carry a payload of sophisticated remote sensing equipment that would be dedicated to imaging southern Africa.There’s an interesting aside to this technology. Communications satellites are in a geostationary orbit, with thrusters constantly keeping them in the same position above the earth. Earth orbit satellites like Sunsat and Sumbandila, on the other hand, actually orbit the earth, with the force of gravity maintaining their positions. They only need to use their thrusters (if they have any) to make small adjustments.These orbits are determined by the job the satellites have to do. Sumbandila is intended to take satellite images of southern Africa. When it is finally launched, it will be put into an orbit that takes it over that part of the world at a convenient 10am, about the best time for high-level imaging.So of the three satellites SunSpace has so far built, one is still on earth, waiting for its chance to shine, one is busy sending earth images to its anonymous owner, and one is still up there, but not operational. It’s what some people might call space debris but let’s rather think of it as a permanent orbiting monument to African ingenuity and technological progress.In the words of Ron Olivier, business manager of SunSpace, “I look forward to the day an African astronaut is launched on board an African spacecraft launched on an African rocket from the African continent.’ Big dreams, but 20 years ago, who would have thought there’d be a South African-designed satellite orbiting above our heads?Do you have queries or comments about this article? Email Mary Alexander at [email protected] articlesGoogle to put Africa onlineSouth Africa’s aerospace industry takes offAfrican eyes on the universeUseful linksSunSpaceUniversity of Stellenbosch Hermanus Magnetic ObservatorySouth African Space Portal
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The building-science-and-beer group that meets every month in Portland, Maine, recently launched a discussion of suggested specifications for a “pretty good house” — a house that seeks to balance construction cost and energy performance without being constrained by the dictates of existing green building programs or rating systems. Michael Maines’s blog on that topic has generated dozens of comments, and GBA has received several e-mails from readers with suggestions for regional variations on the “pretty good house” concept.So, without further ado, we present the Pretty Good Ontario House, the Pretty Good New Mexico House, the Pretty Good Sacramento House, the Pretty Good Florida House, and the Pretty Good North Carolina House.Lucas Durand: Northwest OntarioSince I was not particularly interested in any type of “official” certification for my new house in northwest Ontario, I began to pick and choose criteria that seemed reasonable from both a cost and performance standpoint. RELATED ARTICLES The Pretty Good HouseThe Pretty Good House, Part 2Martin’s Pretty Good House ManifestoThe Pretty Good House: A Better Building Standard?Is the Pretty Good House the Next Big Thing?Is the Pretty Good House the Next Big Thing? Part 2 Mike Keesee: Sacramento, CaliforniaAt SMUD (the Sacramento Municipal Utility District), we’re big fans of pretty good house. We call our version of the pretty good house the “SolarSmart Home.” SolarSmart Homes included following measures:R-38 attic insulationAttic radiant barrierR-13 wall insulation plus R-4 rigid foamEnergy Star windowsMinimum furnace efficiency: 90 AFUEAC specs: minimum 14 SEER and 12 EERCFL lighting1 kW to 2 kW PV systemLimited bill analysis shows that SolarSmart homeowners are using 50% less energy and saving about 54% on their electric bills vs. a control group. (We attribute the smaller savings to increased plug loads).Although we’re thrilled with the results, we knew we had to do better. To that end, we developed a HOme of the Future (HOF) R&D program. The goal of the R&D was to develop a package of energy efficiency measures combined with PV and solar thermal to reduce total annual source energy use by 80%:R-50 ceiling insulationR-30 wall insulationConditioned crawl space with R-10 wall insulationWindows rated at U-0.30 and 0.26 SHGCMinimum furnace efficiency 92 AFUEAC specs: minimum 18 SEER and 12 EERHVAC system designed according to ACCA specsDucts located inside conditioned spaceMechanical ventilation systemDomestic hot water: solar thermal system plus tankless gas heaterHVAC system commissioning includes verification of refrigerant charge and airflow over coilAir leakage rate: 4 ach50CFL lighting3.5 kW to 4 kW PV systemIn brief, we’re convinced that a “packaged” approach provides consistent results and a “pretty good house.”Don’t get me wrong. I like Passivhaus, LEED, Greenbuilt, and the other green home programs. They push the envelope and set upper standards, but we need to recognize that these programs are not applicable for the huge majority of cases and will never achieve the market penetration we need if we want to achieve the energy savings we need to in new and existing homes. As laudable as these programs are, they are overly complicated, expensive, and in certain cases dogmatically rigid. Home buyers and owners, builders and contractors need easy to understand and implement and affordable solutions. Our experience at SMUD tell us that if we can deliver easy-to-understand, easy-to-implement affordable programs, our customers will respond. Neil Porter: FloridaI live in Fort Myers, Florida. Our highs in January and February have often been in the 70s-80s. Basically there are only a couple days a year when it would be good to have solar gain through the windows. Otherwise it is never needed and definitely not desired.No east or west windows. Good design for south Florida means no windows on the east and west walls because the low morning and afternoon sun heats up the home year-round and greatly increases the cost for air conditioning. North-facing windows are great because they only get early morning and late afternoon sun before and after June 21. With the sun at 85 degrees at noon on that date, it doesn’t take much of an overhang to shade south-facing windows.Put the lanai on the north side of the house. Ideally the front would face south. In our area virtually no porches have been built on the fronts of homes for decades. Most homes have a screened enclosure (called a lanai here) in the back. This is because six months of the year we have a lot of mosquitoes. Usually a double sliding glass door from the dining room and often from the master bedroom and sometimes from a second bedroom lead to the lanai. Having these large glass surfaces face north reduces a lot of solar gain. Having the lanai face north also keeps it much cooler because the house and roofed portion keep it shaded. A lanai that faces west, south or east is much less comfortable nine months of the year. The lanai should also jut out from the back of the home with screens on three sides to benefit from cooling breezes.Wide overhangs aren’t good in hurricane territory. When I first started researching green building in Florida, wide roof overhangs were recommended. But when hurricane resistance entered the picture, as it must in all of Florida, overhangs shrank to one foot. The exception is the covered portion of our lanais. These are called “under truss” because they are integrated into the home’s roof. The trusses are supported by a poured concrete tie beam which rest on concrete pillars.You don’t need thick insulation or expensive windows. To understand this, northern people need to keep our climate in mind. For the most part we design for efficient air conditioning at least six months of the year. There are exceptions but generally our hottest temperatures are about 95 degrees. Keeping the interior air conditioned to 76-78 degrees means that there is only a 17-19 degree difference in the summer afternoons. As a result, thick insulation on walls and expensive insulated windows is not a good use of available funds. Tight-fitting windows with reduced air infiltration, on the other hand, is a good thing because of our high humidity which is generally 80-100% every night year-round. This high humidity at night coupled with 80-85 degrees still at midnight means that we can’t open windows at night during our long summers. For most people the home is kept tightly closed for six months once the temperatures get too hot.Choose reflective roofing. A major part of our heat gain is through the roof, so having a highly reflective and emissive white metal roof should be one of the top priorities. Whereas a heat-absorbing shingle roof lasts about 20 years at best in this climate, a metal roof will last 40-50 years. Shingles then usually go to the dump. Metal, on the other hand, can be easily recycled. Metal roofing is also much more resistant to hurricane-force winds. The downside is that metal is about twice as expensive.Choose light-colored siding paint and plant vegetation. Since many homes here are built with uninsulated concrete blocks, using light-colored exterior paint or shading the walls with vegetation can help reduce energy costs.Install a solar hot water system. Get a solar water heater in every existing and new home and accomplish a reduction in energy use for a small investment and short-term payoff.Include an unvented conditioned attic. Insulating the underside of the roof sheathing with spray foam not only insulates an unvented attic keeping the humidity out but also greatly increases the uplift resistance to hurricane-force winds. Also, since air conditioner ducts are always installed in our attics and often the air handler, reducing the attic temperature in this way greatly reduces the heat transferred to the ducts.Install a programmable thermostat. For people that are regularly away from the home for several hours a programmable thermostat with an unoccupied temperature of 85 degrees can greatly reduce energy costs. Leigha Dickens: North CarolinaHere are the design principles I follow when advising customers who want to build a Pretty Darn Green home in my mountainous, mixed-humid climate:Passive design first of all! Do use south-facing windows, thermal mass, and super-insulation for passive solar heating. Yet don’t cut down those trees, if you have them: the provide many dollars worth of summer cooling, and deciduous trees which lose their leaves in winter will still allow in a great deal of sunlight. Avoid east and west facing windows, as low-angle sun in summer can add a lot of extra heat when it’s not wanted. Also, resist the urge to “oversize” your passive solar by building what amounts to an attached greenhouse on the south side of your home: work with a design professional to get the glass-to-thermal-mass ration right. I have seen so many homeowners regret that their large south-facing space becomes virtually unlivable in the swing seasons because they put in too much south-facing glass. A little goes a long way in this particular climate, especially as winters can have remarkably warm spells intermixed with the cold.Start with R 10-15-30-50 for superinsulation. Blown-in blankets or cellulose, rather than batts which tend to be installed poorly, are a well-performing and cost-effective choice for walls, while cellulose or spray foam insulation are good for the ceiling or roof deck.Incorporate livable outdoor space like covered or screened porches, patios, and decks. There’s a good chunk of the year when it’s darn nice outside, and having outdoor space can make smaller indoor square footages feel more comfortable.Install a high-efficiency heat pump and AC and have a thorough mechanical design and commissioning to avoid oversizing. Keep the ductwork and air handler inside of the building envelope, or go ductless with mini-splits. The subject of air conditioning is as hot button among green types, and I’ll admit to being captivated by the romance of natural ventilation and the energy savings of AC-free living. However, in our occasionally-very-cold but mostly-mild winters, you can’t beat a heat pump for energy efficient heating, which means the ductwork and machinery is essentially already in place for air-conditioning, as well. And a large part of what an AC does (when not oversized) is dehumidify. Humidity can make even an otherwise pleasant temperature feel very uncomfortable, and we have a lot of it. It can also create an ideal environment for indoor mold and mildew growth, impacting occupant health and reducing the durability of interior finishes.Build a home with solid moisture-management techniques. Although that is important in any climate, it rains a lot here and is very often quite humid, so there is less margin for error. Sloping lots, deep overhangs, gutters, a behind-the-siding drainage plan, correct wall and roof flashing, capillary breaks. Building assembly components must be built to dry in both directions: so vapor barriers on any side of the enclosure should be avoided.Solar electric, wind, solar thermal, geothermal are the icing on the cake and should be considered only after you’ve built a passive, super-insulated, reasonably air-tight home and durable home with a modest footprint. Armando Cobo: New MexicoI’ll start a list for Southern design criteria:Passive solar design should be the first priorityInclude large overhangs and porchesInsulation levels can be lower that for cold-climate housesTriple glazing is not neededInstall reflective roofsSelect light-colored materials Resiliency was a priority, with most of the attention on making the house livable in the event of extended power outages and during times of drought.Simplicity of design. I found it best to keep everything as simple as possible. In terms of envelope design, simplicity had a lot to do with keeping everything buildable but also with minimizing complex geometry. In terms of resiliency, simplicity meant covering the basics by making decisions about what was needed and then not worrying about devising systems that would maintain what was wanted.A vented attic was selected for cost, ease of construction and also for durability reasons. The underlying flat ceiling also offers more buildability and better performance than a more dramatic cathedral ceiling.Wall trusses with airtight sheathing. The walls are a type of stick-framed truss wall with airtight sheathing. As with the vented attic, this wall system was selected for its buildability but also because of my desire to minimize the use of rigid foam insulation.5/10/20/40/60 insulation. For insulation, I followed the 5/10/20/40/60 guideline, but found it easy to add a little extra here and there (ie: sub-slab, sub-footing). It is my thinking that it is more important to focus on the quality of the insulation plan rather than the quantity. A complete thermal break around the entire envelope should be a priority; footings and slab should be fully insulated.0.6 ach50. Air-sealing details should aim for the tightest possible construction but should be relatively easy to accomplish. Committing ahead of time to a service cavity enabled the use of certain air-sealing details that make Thorsten Chlupp’s “0.6ACH50 made easy” achievable.“Outie” windows may not offer the maximum performance advantage but are much easier to install and detail. Because of the climate I live in, locating the windows on the “outie” plane increases the risk for condensation in winter, so I bought the best triple-glazed windows I could afford.A rainwater collection system. Regionally, Northwest Ontario has been drying out significantly in recent years. Given that I depend on a well for water, a cistern and rainwater collection system seem like more than just a good idea.A wood stove. The grid can be unreliable during stormy weather. If the grid is knocked out when the outdoor temperature is -20C and there is no source of heat that does not rely on electricity, it becomes possible that the occupants of a house may have to abandon ship. Firewood is plentiful on the property, and an airtight wood stove makes good horse sense.A solar thermal system. For renewable energy, I went with solar thermal for domestic hot water heating, and I plan to incorporate a small amount of PV as budget permits. Solar thermal is a relatively inexpensive way to get into renewable energy systems and, if combined with a small PV system and DC pumping, can increase household resiliency by providing hot running water in the event of grid outages. I avoided the idea of an elaborate PV system for reasons of cost but also for reasons of complexity.My “pretty good house” is still under construction, but I am confident that it will meet my expectations. Once complete I am looking forward to monitoring its performance year after year. Please feel free to follow along with my progress at my blog.