Touchscreens have used a variety of techniques over the last two decades to detect the placement of a finger on a screen—ranging from mechanical, optical, and electrical sensing. Today’s capacitive electrical touchscreens have proven to be the most versatile and efficient way to sense human touch.
A capacitor is an electrical circuit that, in its simplest form, is composed of two conductive electrodes separated by an insulating gap. A direct current (DC) of electricity can’t straddle this gap, but an alternating current (AC) can induce a charge to flow from one side to the other. The surface of a touchscreen is blanketed with a grid of electrodes. Wherever our finger comes to rest, a capacitive contact is formed and the AC current generated within the device induces a corresponding current within our body—which helps span the gap and complete the circuit.
Human beings are good conductors, so using our fingers to close an electrical circuit makes it very easy to detect human touch with high fidelity. If a grid location on the touchscreen is to sense the AC current, there has to be a return [electrical] path. For a touchscreen on a handheld device such as a smartphone, you’re holding it with the other hand, and this completes the electrical loop to the backside of the device, which is electrically grounded. If the touchscreen is part of an installation, such as an ATM, some part of our body is most likely in contact with an electrical ground. It’s very hard (for our bodies) to avoid making a ground contact, which virtually guarantees that humans (or their fingers) can close an electrical loop for capacitive screens.
If it sounds alarming to have electricity passing through your body, worry not. The AC currents in touchscreens are within levels for natural charge conduction in our bodies—and the true revolution and utility of modern touchscreens lies in the rapidity of their responses. The unsung hero is the microcontroller. Behind every electrode on a touchscreen grid lies an embedded microcontroller that has a clockspeed of nanoseconds. It is this fast response time that enables modern smartphones to have such smooth interaction with human touch, and it is this progress that has driven the growing appeal of touchscreens in recent years.
Capacitive sensing has led to unexpected new innovations, such as the leading sensor used in auto safety systems for cars to detect the location of their occupants, and based on a kind of imaging that uses electric fields. With a little cooperation between man and machine, touch-sensitive screens have opened the doors to a host of new interactive technologies.
The positions of the planets next month will mean diminished communications between Earth and NASA’s spacecraft at Mars.
Mars will be passing almost directly behind the sun, from Earth’s perspective. The sun can easily disrupt radio transmissions between the two planets during that near-alignment. To prevent an impaired command from reaching an orbiter or rover, mission controllers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., are preparing to suspend sending any commands to spacecraft at Mars for weeks in April. Transmissions from Mars to Earth will also be reduced.
The travels of Earth and Mars around the sun set up this arrangement, called a Mars solar conjunction, about once every 26 months.
“This is our sixth conjunction for Odyssey,” said Chris Potts of JPL, mission manager for NASA’s Mars Odyssey, which has been orbiting Mars since 2001. “We have plenty of useful experience dealing with them, though each conjunction is a little different.”
The Mars solar conjunctions that occur once about every 26 months are not identical to each other. They can differ in exactly how close to directly behind the sun Mars gets, and they can differ in how active the sun is. The sun’s activity, in terms of sunspots and solar flares, varies on a 22-year cycle.
This year, the apparent angle between Mars and the sun (if you could see Mars against the glare of the sun–but don’t try, because it’s dangerous to the eyes) will slim to 0.4 degree on April 17. The sun is in a more active period of solar flares for its current cycle, compared to the 2011 conjunction, but this cycle has been relatively mild.
“The biggest difference for this 2013 conjunction is having Curiosity on Mars,” Potts said. Odyssey and the Mars Reconnaissance Orbiter relay almost all data coming from Curiosity and the Mars Exploration Rover Opportunity, as well as conducting the orbiters’ own science observations.
Transmissions from Earth to the orbiters will be suspended while Mars and the sun are two degrees or less apart in the sky, from April 9 to 26, with restricted commanding during additional days before and after. Both orbiters will continue science observations on a reduced basis compared to usual operations. Both will receive and record data from the rovers. Odyssey will continue transmissions Earthward throughout April, although engineers anticipate some data dropouts, and the recorded data will be retransmitted later.
The Mars Reconnaissance Orbiter will go into a record-only mode on April 4. “For the entire conjunction period, we’ll just be storing data on board,” said Deputy Mission Manager Reid Thomas of JPL. He anticipates that the orbiter could have about 40 gigabits of data from its own science instruments and about 12 gigabits of data from Curiosity accumulated for sending to Earth around May 1.
NASA’s Mars Exploration Rover Opportunity is approaching its fifth solar conjunction. Its team will send no commands between April 9 and April 26. The rover will continue science activities using a long-term set of commands to be sent beforehand.
“We are doing extra science planning work this month to develop almost three weeks of activity sequences for Opportunity to execute throughout conjunction,” said Opportunity Mission Manager Alfonso Herrera of JPL. The activities during the conjunction period will not include any driving.
Curiosity, the newest asset on Mars, can also continue making science observations from the location where it will spend the conjunction period. Curiosity’s controllers plan to suspend commanding from April 4 to May 1.
“We will maintain visibility of rover status two ways,” said Torsten Zorn of JPL, conjunction planning leader for the mission’s engineering operations team. “First, Curiosity will be sending daily beeps directly to Earth. Our second line of visibility is in the Odyssey relays.”
JPL, a division of the California Institute of Technology, manages the projects operating both NASA Mars orbiters and both Mars rovers for NASA’s Science Mission Directorate, Washington.
NASA and the Department of the Interior’s U.S. Geological Survey (USGS) have released the first images from the Landsat Data Continuity Mission (LDCM) satellite, which was launched Feb. 11.
The natural-color images show the intersection of the United States Great Plains and the Front Range of the Rocky Mountains in Wyoming and Colorado. In the images, green coniferous forests in the mountains stretch down to the brown plains with Denver and other cities strung south to north.
LDCM acquired the images at about 1:40 p.m. EDT March 18. The satellite’s Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments observed the scene simultaneously. The USGS Earth Resources Observation and Science Center in Sioux Falls, S.D., processed the data.
“We are very excited about this first collection of simultaneous imagery,” said Jim Irons, LDCM project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “These images confirm we have two healthy, functioning sensors that survived the rigors of launch and insertion into Earth orbit.”
Since launch, LDCM has been going through on-orbit testing. The mission operations team has completed its review of all major spacecraft and instrument subsystems, and performed multiple spacecraft attitude maneuvers to verify the ability to accurately point the instruments.
The two LDCM sensors collect data simultaneously over the same ground path. OLI collects light reflected off the surface of Earth in nine different regions of the electromagnetic spectrum, including bands of visible light and near-infrared and short-wave-infrared bands, which are beyond human vision. TIRS collects data at two longer wavelength thermal infrared bands that measure heat emitted from the surface.
By looking at different band combinations, scientists can distinguish features on the land surface. These features include forests and how they respond to natural and human-caused disturbances, and the health of agricultural crops and how much water they use. Data from LDCM will extend a continuous, 40-year-long data record of Earth’s surface from previous Landsat satellites, an unmatched, impartial perspective that allows scientists to study how landscapes all across the world change through time.
“These first scenes from the new Landsat satellite continue the remarkable output from the Landsat program with better, more useful imagery and information,” said Matthew C. Larsen, associate director for climate and land use change at the U.S. Geological Survey in Reston, Va. “We are gratified that this productive partnership between USGS and NASA has maintained the continuity and utility of this essential satellite tool, providing the foundation for land and water management around the globe.”
As planned, LDCM currently is flying in an orbit slightly lower than its operational orbit of 438 miles (705 kilometers) above Earth’s surface. As the spacecraft’s thrusters raise its orbit, the NASA-USGS team will take the opportunity to collect imagery while LDCM is flying under Landsat 7, also operating in orbit. Measurements collected simultaneously from both satellites will allow the team to cross-calibrate the LDCM sensors with Landsat 7’s Enhanced Thematic Mapper-Plus instrument.
“So far, our checkout activities have gone extremely well,” said Ken Schwer, LDCM project manager at Goddard. “The mission operations team has done a tremendous job getting us to the point of imaging Earth.” During the next few weeks, this team will calibrate the instruments and verify they meet performance specifications.
After its checkout and commissioning phase is complete, LDCM will begin its normal operations in May. At that time, NASA will hand over control of the satellite to the USGS, which will operate it throughout its planned five-year mission life. The satellite will be renamed Landsat 8. USGS will process data from OLI and TIRS and add it to the Landsat Data Archive at the USGS Earth Resources Observation and Science Center, where it will be distributed for free via the Internet.
For more information on these first LDCM images, visit: http://go.nasa.gov/13cHhFJ
For more information on the LDCM mission, visit: http://www.nasa.gov/landsat
NASA’s Operation IceBridge scientists have begun another season of research activity over Arctic ice sheets and sea ice with the first of a series of science flights from Greenland.
A specially equipped P-3B research aircraft from NASA’s Wallops Flight Facility in Wallops Island, Va., is operating out of airfields in Thule and Kangerlussuaq, Greenland, and Fairbanks, Alaska. The flights will carry out survey flights over land and sea ice in and around Greenland and the Arctic Ocean through early May.
NASA began the Operation IceBridge airborne campaign in 2009 as a way to continue the record of polar ice measurements made by NASA’s Ice, Cloud and Land Elevation Satellite’s (ICESat) after the satellite stopped gathering data. By flying campaigns in the Arctic and Antarctic each year, IceBridge is maintaining a continuous record of change until the launch of ICESat-2 in 2016.
This year’s IceBridge campaign will continue closely monitoring Arctic sea ice and key areas of the Greenland ice sheet, while expanding coverage in Antarctica.
“Our long term plan, beginning with the Arctic 2013 campaign, is to scale back the land ice portion of the campaign while maintaining the same coverage of sea ice as in previous campaigns,” said Michael Studinger, IceBridge project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Dramatic changes to Arctic sea ice, such as the record-breaking minimum levels reached in 2012, and the potential societal effects of ice loss in the region are driving the demand for sea ice measurements. The mission will survey areas of Arctic sea ice near Greenland with flights out of the U.S. airbase in Thule. IceBridge also will carry out a series of flights from Fairbanks to measure ice in the Beaufort and Chukchi seas north of Alaska. Researchers will gather critical data during their flights between Greenland and Alaska.
In addition to sea ice, IceBridge will survey the Greenland Ice Sheet in the interior of the country and in rapidly changing areas along the coast, such as the Jakobshavn Glacier.
“We’re starting to see how the whole ice sheet is changing,” Studinger said. “Thinning at the margins is now propagating to the interior.”
IceBridge scientists will collaborate with other groups doing research in the region, such as the U.S. Army Corps of Engineers Cold Regions Engineering Laboratory in Hanover, N.H., and the Naval Research Laboratory (NRL) in Washington. The laboratories are working together to collect snow depth measurements on Elson Lagoon near Barrow, Alaska, to help NRL evaluate a snow radar they are using.
Joining the IceBridge team are three teachers who will spend time working with the researchers to learn about polar science. High school science teachers from Libertyville, Illinois; Aalborg, Denmark; and Sisimiut, Greenland, will spend time aboard the P-3B during IceBridge survey flights.
IceBridge is providing these teachers with a research experience they can use to better teach science and inspire their students to study scientific fields. The teachers’ involvement is the result of a partnership with the U.S. State Department, the governments of Denmark and Greenland, and the National Science Foundation-funded Polar Teachers and Researchers Exploring and Collaborating program.
For more about Operation IceBridge and to follow this year’s campaign, visit: http://www.nasa.gov/icebridge
For more about PolarTREC and the IceBridge teacher research experience, visit: http://go.nasa.gov/13cycwM
Sorry for the lack of action on the blog in recent weeks. My illness has gotten the better of me which has meant the last thing I have wanted to do was sit in front of a PC.
To make up for it, watch this artist at work!
Paying tribute to a scientific genius
Professor Stephen Hawking is perhaps the world’s most famous living physicist. A specialist in cosmology and quantum gravity and a devotee of black holes, his work has probed the origins of the cosmos, the nature of time and the universe’s ultimate fate — earning him accolades including induction into the Order of the British Empire. To the public, he’s best known as an author of bestsellers such as The Universe in a Nutshell and A Brief History of Time, which have brought an appreciation of theoretical physics to millions.
Professor Stephen Hawking is without question one of the most brilliant theoretical physicists in history, and when he wrote the modern classic A Brief History of Time it not only brought the origins of life debate to people who perhaps had not previously considered science let alone physics, it also opened a new world to those without education in order to help non-scientists understand fundamental questions of physics and our existence. His accomplishments are world renowned and recognised by even recently opening the London 2012 Paralympic Games.
For me the man is an inspiration and one of the reasons I embarked on the exciting journey that is science. In 1963, Hawking contracted motor neurone disease and was given just two years to live. Yet despite this he went on to Cambridge to become a brilliant researcher and Professorial Fellow at Gonville and Caius College. Since 1979 he has held the post of Lucasian Professor at Cambridge, the chair held by Isaac Newton in 1663. Professor Hawking has over a dozen honorary degrees and was awarded the CBE in 1982. He is a fellow of the Royal Society and a Member of the US National Academy of Science. Prof. Stephen Hawking is quite rightly regarded as one of the most brilliant theoretical physicists since Einstein.
So, Happy 71st Birthday Professor Hawkings, from a fan, and admirer of your scientific accomplishments!
Question: Why do Stars Twinkle?
Stars twinkle because their light must pass through pockets of Earth’s atmosphere that vary in temperature and density, and it’s all very turbulent. On rough nights, a star appears to shift position constantly as its light is refracted this way and that.
One could liken it to watching a coin appear to dance at the bottom of a pool, it gives the impression of movement when it is stationary.
To overcome the twinkling Astronomers use adaptive optics, in which many small mirrors on the scope adjust constantly to allow for the atmospheric disturbances. They can also use space-based telescopes to make observations. Of course, telescopes orbiting Earth above the atmosphere avoid the problems caused by turbulence.
Meet Laika, the dog who—quite literally—went where no man had gone before (or woman, for that matter).
In November of 1957, the Russians planned to launch Sputnik 2, their second Earth-orbiting satellite. After the success of Sputnik 1 (the first satellite to orbit the Earth), the Russians hoped that Sputnik 2 would provide invaluable information regarding the impact that spaceflight would have on living passengers. The main aim of the project was to determine whether humans would be able to tolerate weightlessness and survive being launched into orbit. Of course, it would be cruel to send humans into space without knowing whether or not they could survive the trip.
A two year old Husky mix, Laika was a stray that was found wondering the streets of Moscow. Since she was a stray, Laika was used to living under harsh conditions. Moreover, she had a calm and quiet temperament; couple this with her small size, and Laika was the ideal candidate for spaceflight.
For Laika, this was a death sentence.
Making provisions for Laika’s safe return would have taken time. Focused on beating the United States in the Space Race, time was one thing that the Russians did not want to spare. So Sputnik 2 was not designed to be retrievable. Laika was never meant to return to Earth. Several days prior to the launch, Dr. Vladimir Yazdovsky, one of the lead scientists working on the mission, took Laika home to play with his children. He later stated, “I wanted to do something nice for her; she had so little time left to live.”
Then, on November 3rd 1957, Laika made history by becoming Earth’s first space traveler. Originally, Laika was expected to live for roughly a week. However, shortly after entering orbit some of the thermal insulation tore loose, causing interior temperatures to reach 40C (104F). Due to the extreme temperature, and the extraordinary amount of stress on the little dog, Laika almost certainly died during the first day of flight, most believe she perished just a few hours after launch.
Sputnik 2 orbited a total of 2,570 times. On April 14, 1958, after nearly162 days in orbit, Laika’s craft reentered Earth’s atmosphere and burned.
In 1997, the Russians made a monument to honor fallen Soviet cosmonauts. Peering out from behind the statue, an image of the tiny canine.
Her name was Laika. She was the first Earthling to enter space. And she was the only living creature who was sent without a recovery system in place.
Sources and Further Research:
I have just seen a variation of the above on the Thinking Atheist’s Facebook page and to be quite honest it really fucking annoyed me.
So Mr/Mrs Religious Person, I want to deal with you and any like-minded fools right here on my blog.
I put it to you, that if your faith is so strong, you should never be a burden on the NHS or any other health service private or state. You should never visit a physician let alone a GP. For whatever happens to you is all part of ‘God’s’ plan isn’t it? or are you a blatant hypocrite?
- How is one form of medicine acceptable over another?
- How is one form of warfare (biblical) acceptable over another (any war since)?
- How is one form of rape (in the bible a rapist had to marry a woman he had raped – so who got punished there then? – and as long as the rapist did this all was ok) acceptable?
- How is pedophilia acceptable if the pervert says he’s sorry and therefore has admonished his sins in a closed ‘court of law’ and allowed to continue freely without the ‘congregation’ being any the wiser and the local law enforcement also kept in the dark?
Isn’t that why innocent women and children are murdered, raped, abused and tortured? Isn’t that why war continues even as you read this article? Isn’t every awful, unfair and evil thing that happens all part of his master plan, to get humans to find him and repent of their sins and follow meekly in his footsteps – what ever medieval religion or cult thousands of fools would have you follow?
Fuck you asshole! Religion and belief in a God is the main reason and cause of most pain occurring since time began. HOW DARE YOU ATTEMPT TO FORCE YOUR BELIEFS ON ME OR ANYONE ELSE – AND THEN DISRESPECT ME WHEN I POLITELY POINT OUT THAT SCIENCE IS ACTUALLY CORRECT, be it evolution or otherwise.
The person who posted their little Hallelujah on their Facebook status is a deluded disrespectful …. cancer survivor.
It was Medical Science that saved my son when at 9 weeks had a cerebral aneurysm the like physicians had never seen before (they took pictures of it for medical journals) in an adult let alone a tiny little boy, was removed successfully. He is now almost 7 and I thank the doctors and medical staff for their skill that he is.
Every year far too many parents rely on faith to heal their child and force their beliefs on their kid who is unable to make a choice, and then lament when the poor child dies unnecessarily. Religion and faith are responsible for far too many unnecessary deaths, be it in war, in the operating theatre or elsewhere.
A wise man once said “We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology” – Carl Sagan, and a medieval belief in a non-existent entity should’ve stopped when humanity no longer considered Thor, Zeus, Hercules and the gang real – the mentality that ‘god’ is real and has a plan for us mere mortals. No. It stops now.
I am sick and tired of these people forcing their misguided and outdated beliefs on people and then having the audacity to be dismissive of Medical Science, skilful scientists, biologists, doctors, physicians et al. And then tell me that I am forcing my non-believing ‘disrespectful’ ‘harmful’ ‘apostate’ etc views on them!
Stop being so damned small-minded and do some BASIC research, and maybe, just maybe we can talk. Try reading ‘Who Wrote the Bible’ by Richard Elliot Friedman.