Ground tracks of 30 NAVSTAR GPS satellites.The time span covered by each ground track is five hours (time rate is 1000x real time).
This month, the first Block IIF GPS satellite will launch from Cape Canaveral. It will be the fist of 12 new ones, which U.S. Air Force ordered at Boeing and this campaign is a part of the GPS Modernization Program.
Boeing delivered also the 39 other SV's (Block I and Block II/IIA). The new GPS IIF features twice the navigational accuracy of the current satellites (advanced atomic clocks greatly improving performance and giving the control segment greater visibility into the health of the units) and should deliver more robust signals for aviation and SAR (probably also for Photogrammetry and Surveyors), meaning the new L5 signal. The new Block of SV's id designed for a 12 years life time period. Navstar GPS Block IIF will be the end of the current generation of GPS satellites. Actually, these new satellites each transmit three civilian GPS signals (we’ve typically been making do with just one for years) including a military-strength transmission that should enable autopilots to land with zero visibility. A three-signal world will mean always-on GPS that’s accurate to within 3 feet (even indoors and in concrete urban canyons).
An official military announcement also laid out the 24+3 (“Expandable 24”) consisting to move three existing GPS satellites to new orbit locations will have a profound effect on GPS capabilities for all civil, commercial, and military users worldwide.
In the future, the next-generation GPS system (Block IIIA) will introduce new capabilities to meet higher demands of military and civilian users. The system is looking ahead to its first launch in 2013. Note : Galileo is still coming up (2014) Block IIIA will offer the opportunity for a cross-linked command and control architecture, allowing the entire GPS constellation to be updated from a single ground station instead of waiting for each satellite to orbit into view of a ground antenna. Block IIIA will also support a new L1C civil signal, and a spot beam antenna that provides resistance to hostile jamming while improving its accuracy and integrity.
Sea levels are rising everywhere, but in some areas they are rising quicker than others, bringing increased dangers of flooding.
The altimetry project stretches back to 1992, and provides the global reference data for satellite-measured ocean surface topography. It is the Jason series and its predecessor, the Topex/Poseidon spacecraft, that have traced the recent 3mm per year rise in sea levels.
The surface height information has been invaluable to oceanographers, weather forecasters and climatologists.
On 2 February 2010 EUMETSAT announced that the Jason-3 ocean altimetry satellite Programme was approved by EUMETSAT Member States which will ensure a continuation for 2013-2014 of the series of measurements made by the Jason-2 satellite and its predecessors.
Jason-2 provides a vital contribution to the monitoring of climate change, ocean circulation and weather and already supplies the data continuity that is essential for measuring the sea level trend, one of the key indicators of climate change.
Jason-3 will continue the mission, ensuring thus the measurement of rising sea levels carried out by Jason-2, Jason-1 and TOPEX/Poseidon over the last 18 years.
Big wave surfing is the extreme frontier of a fairly extreme sport. Big waves, or waves over 20 feet in height, add a whole new element to surfing that requires special boards, skills and methods of dropping into the wave. The rewards of surfing big waves are as big as the waves themselves, but with those big waves and thrills comes serious risks.
Follow these steps to surf big waves : (from ehow.com)
Work up to big waves : when you're on the water, even a 10-foot wave seems like a giant. So getting to the point where you can (almost) fearlessly stare down a 20- or 30-foot wave takes lots of time on the water. Work your way up by surfing bigger and bigger breaks until you feel like you're ready to take the monsters of surfing.
Get the right board : surfing big waves requires special skills and, just as importantly, a special board. Big wave boards, known as guns or rhino chasers, are longer, faster and more stable than most other boards. You need to find a board that is made for your height and weight and can also handle the size and speed of the waves you plan to surf.
Tow in : towing in is a special technique for surfing big waves that involves high powered jet skis towing the surfers, on their boards, into the waves just before they start to break. Towing in is not a fun option but a physical necessity to surf big waves, so find someone who knows how to tow to train you how to get towed into a big wave.
Learn to wipe out : there are many ways to fall off a big wave. When you're surfing down the face of a wave at 50 MPH you need to know the correct and incorrect way to fall. Knowing how to hit the water, hold your breath and get tossed by the wave are not just important but essential skills in surfing big waves since, as any big wave surfer will tell you, the one thing you can't avoid in big wave surfing is the occasional wipeout...
Water ferns have tiny hairs that are super hydrophobic. Their properties, if applied in real life conditions to a sail boat, for example, could lead to a reduction of up to 10 percent of the boat’s fuel consumption by reducing friction. Until now, the researchers didn’t quite understand how aquatic ferns work, but some scientists from the University of Bonn, Rostock and Karlsruhe showed the exact process in the journal Advanced Materials. The scientists used the water fern salvinia molesta, which is extremely hydrophobic. Using such properties in swimsuits, for example, could make them quick-drying and ships would be very efficient. The salvinia molesta surrounds itself by a skirt of air, preventing the plant from coming into contact with the liquid. And the effect lasts a few weeks.
Hydrophobic materials had been discovered, but their properties don’t last that long – not to mention as long as to be put on ships who cruise for weeks/months. The best such material only has a few hours of stability, after which it vanishes. The challenge is to make hydrophobic materials that last at least as water ferns do. The water fern has been found out to use its tiny hydrophobic whisk-like hairs on the surface of its leaves to repel water and keep it at distance. And that’s not all: “We were able to show that the outermost tips of these whisks are hydrophilic, i.e. they love water,” Professor Wilhelm Barthlott from the University of Bonn explains. “They plunge into the surrounding liquid and basically staple the water to the plant at regular intervals. The air layer situated beneath it can therefore not escape so easily.” The professor also estimates that, by being huge fuel-guzzlers, ships could make a difference in the worldwide fuel savings if they’re “tuned” to be more efficient – “probably one percent of the fuel consumption worldwide could be saved this way,” he says.
Today, some antifouling coating method (but not bio) increases the ship's efficiency by reducing drag while also protecting the ocean from biocides that may leak. Instead of biocides, used by much of the industry to keep barnacles off of the hull, a special silicone-based paint is used. The silicone paint covering the part of the hull below the waterline is credited for lowering the water drag enough to save 1200 tons of fuel per year for the 'Emma Mærsk' ship.
Australian Navy has approved the use of an Adelaide designed electronic shark deterrent following an attack on one of its divers last year.
The Adelaide-based Shark Shield company said the Navy accreditation and clearance followed seven months of testing after able seaman Paul de Gelder was attacked by a shark during a training exercise in Sydney Harbour in February, 2009 and lost his right hand and right leg in the attack.
The basic Shark Shield device weighs about 380 grams and is small enough to fit into a person's hand. Another version has been designed to be fitted to surfboards.
The Australian Navy approval should spark an increase in international and local orders for the Shark Shield technology, the company said.
Chairman Grant Price said the device emits electric impulses that cause great discomfort to sharks. Sharks have hundreds of electro-receptors in their snouts, which pick up the minute electrical impulses emitted by living creatures in the water. A Shark Shield emits impulses of greater intensity which cause sharks discomfort at a range of up to 8m.
If the shark moves further into the field they experience muscle spasms that are enough to deter an attack.
Mr Price said the Navy had chosen the Shark Shield as the most effective technology available.
"The Navy tested our product under a variety of conditions for seven months and has found it meets all criteria to improve the safety of its divers," he said.
"We are receiving enormous international interest in our device and expect general inquiries to translate to firm agreements as it becomes known that the Australian Navy relies on our technology.
"We are also hoping to extend the relationship with the Navy to supply Shark Shield to other military personnel."
Mr Price said Australia was known to have some of the most shark-populated waters on the planet, so what was seen to work in Australia had international credibility.
The device could also be used for swimmers, kayakers and fishers.
