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Posted: 22 Feb 2015 06:10 AM PST
In the movie 'Contact', astronomers receive a radio signal from the star Vega. Buried within the signal is a broadcast of Hitler’s speech for the opening of the 1936 Olympic games. The television signal had made the 25 light year journey to Vega, which let the aliens know we’re here. The idea that our television and radio signals are gradually reaching ever more distant stars is a popular one, but in reality things aren’t so simple. The opening ceremony of the 1936 Olympics was the first major television signal at a frequency high enough to penetrate Earth’s ionosphere. From there you could calculate that any star within about 80 light years of Earth could detect our presence. There’s even a website that shows which TV shows might be reaching potentially habitable worlds. But the problem with this idea is that it isn’t good enough for the signal to reach a distant star, it also needs to be powerful and clear enough to be detectable.
For example, the most distant human-made object is Voyager I, which has a transmission power of about 23 Watts, and is still detectable by radio telescopes 125 AU away. Proxima Centauri, the closest star to the Sun, is about 2,200 times more distant. Since the strength of a light signal decreases with distance following the inverse square relation, one would need a transmission power of more than 110 million Watts to transmit a signal to Proxima Centauri with the strength of Voyager to Earth. Current TV broadcasts (at least in the States) is limited to around 5 million Watts for UHF stations, and many stations aren’t nearly that powerful.
One might argue that an advanced alien civilization would surely have more advanced detectors than we currently have, so a weaker signal isn’t a huge problem. However the television signals we transmit aren’t targeted at space. Some of the signal does leak out into space, but they aren’t specifically aimed at a stellar target the way Voyager I’s signal is aimed at Earth. They also lack a clear mechanism for how transform the signal to an image. On Earth this works by implementing a specific standard, which any alien civilization would need to reverse engineer to really watch TV. On top of that, there is the problem of scattering and absorption of the signal by interstellar gas and dust. This can diminish the power and distort the signal. Even if aliens could detect our signals, they might still confuse it with background noise.
That doesn’t mean it’s impossible to communicate between stars. It just means that communication would require an intentional effort on both sides. If you really want to communicate with aliens, you need to make sure your signal is both clear and readable. To make it stand out among all the electromagnetic noise in the universe, you’d want to choose a wavelength were things are relatively quiet. One good region is known as the water hole, which spans a range from 18 to 21 cm. Hydrogen (H) emits at about 21 cm, and hydroxyl (HO) has a strong emission at about 18 cm. Together they can form water, hence the name for the quite gap in between. You also need to make your signal easy to recognize as an artificial signal. In Contact the aliens did this by transmitting a series of prime numbers.
In 1974 humanity made its most famous effort to send a signal to the stars. It was a radio transmission sent from the Arecibo observatory, and consisted of 1,679 binary digits, lasting three minutes. Since 1,679 is the product of the primes 23 and 73, the bits can be arranged into an image of those dimensions. There have been other efforts to send messages to the stars, but they haven’t been as powerful or as simple.
Beyond a few light years, our leaky TV broadcasts are likely undetectable. As we’ve switched to digital television and lower transmission powers they’ve become even harder to detect. Any aliens looking for us will have to rely on other bits of evidence, such as the indication of water in our atmosphere or chlorophyl on Earth’s surface, just as we will strive to detect such things on distant worlds. Either way, the first message received won’t be a complex text of information. It will simply be a recognition of life on another world.
Written by: Brian Koberlein
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Brian Koberlein is an astrophysicist and physics professor at Rochester Institute of Technology. Author of "Astrophysics Through Computation" with David Meisel. Creator of the science outreach project Prove Your World, developing a science television show for children."
Check out Brian's blog 'One Universe at a Time' at: briankoberlein.com
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Posted: 22 Feb 2015 04:43 AM PST
One of the India's leading scientists and former Indian Space Research Organisation (ISRO) chairman, G Madhavan Nair, on Saturday propounded the theory that some shlokas in the Vedas mention the presence of water on the moon, and that astronomy experts like Aryabhatta knew about gravitational force much before Issac Newton. The 71-year-old Padma Vibhushan awardee said the Indian Vedas and ancient scriptures also had information on metallurgy, algebra, astronomy, maths, architecture and astrology way before the western world knew about them. Speaking at an international conference on Vedas, he however, added that the information in vedas was in a "condensed format", which he said made it difficult for modern science to accept it.
"Some sholkas in one of the Vedas say that there is water on the moon but no one believed it. Through our Chandrayaan mission, we could establish that and we were the first ones to find that out," Nair said, adding that everything in the Vedas could not be understood as they were in chaste Sanskrit.
He also talked very highly about fifth century astronomer-mathematician Aryabhatta, saying, "We are really proud that Aryabhatta and Bhaskara have done extensive work on planetary work (sic) and exploration of outer planets. It was one of the challenging fields," said Nair.
"Even for Chandrayaan, the equation of Aryabhatta was used. Even the (knowledge of) gravitational field... Newton found it some 1500 years later... the knowledge existing (in our scriptures)," he added.
Nair, who was ISRO chairman from 2003 to 2009, also claimed geometry was used to make calculations for building cities during the Harappan civilisation and that the Pythagorean theorem also existed since the Vedic period.
Mr Nair's come against the backdrop of many BJP leaders talking about ancient Indian scriptures having scientific information, including on plastic surgery and aero-dynamics.
"The Vedas had a lot of information in the field of space and atomic energy. We were fine until 600 BC. Then came the time of invasions till Independence. Since then, we are growing. We deciphered the atoms for peaceful use," Nair said.
While serving in ISRO, Nair had made significant contributions to the development of multi-stage satellite launch vehicles.
"As a scientist, I would say that the computations evolved those days were really fantastic. The Vedanga Jyotisa (one of the earliest books on astronomy) is one of the texts, which is evolved in 1400 BC... this is all recorded," he said.
"These are the fundamental findings which the Western world did not have any knowledge of. The only drawback was this information was condensed to bullet form and the modern science does not accept this. And to read the Vedas, one must also know Sanskrit," Nair added.
Credit: ndtv.com
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Posted: 22 Feb 2015 03:56 AM PST
A Saudi cleric has appeared in a recent video rejecting the fact that the Earth revolves around the Sun and claiming the opposite holds true, prompting a wave of social media remarks. Answering a student question on whether the Earth is stationary or moving, Sheikh Bandar al-Khaibari replied: "stationary and does not move." He then attempted to support his argument by quoting some clerics and selected religious statements. But his most controversial method to debunk the rotation theory was a "logical" deduction in which he used a visual.
“First of all, where are we now? we go to Sharjah airport to travel to China by plane, clear?! focus with me, this is Earth;” he said, holding a sealed water cup.
He argued that if a plane stops still in air “China would be coming towards it” in case the Earth rotates on one direction. It the Earth rotates on opposite direction, the plane would never reach China, because “China is also rotating.”
In separate statements Sheikh al-Khaibari said man never went to the moon, rejecting NASA’s lunar excursion video as Hollywood fabrication.
The video of the sheikh triggered a wave of controversial remarks on social media, especially on Twitter, where a special hashtag is being widely circulated. The hashtag translates as: "#cleric_rejects_rotation_of_
In an interesting remark, one user tweeted: "What a coincidence that this would occur on Galileo's birthday!"
Italian astronomer Galileo Galilei was born on Feb. 15, 1564. He was accused twice of heresy by the church for his beliefs, including his support for the Copernican theory that the earth and planets revolved around the sun.
Meanwhile, some twitter users ridiculed the preacher others said the now popular hashtag should be used to promote and share knowledge of the universe.
Credit: alarabiya.net
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Posted: 21 Feb 2015 02:24 PM PST
NASA astronauts Barry "Butch" Wilmore and Terry Virts floated outside the International Space Station (ISS) Saturday and installed wiring needed for two new docking mechanisms that will be attached later this year for use by new Boeing and SpaceX commercial crew vehicles. The 6-hour, 41-minute spacewalk began this morning at 7:45 a.m. EST. The astronauts completed all the scheduled tasks for today and one get ahead task. They rigged a series of power and data cables at the forward end of the Harmony module and Pressurized Mating Adapter-2 and routed 340 of 360 feet of cable. The cable routing work is part of a reconfiguration of station systems and modules to accommodate the delivery of new docking adapters that commercial crew capsules will use later this decade to deliver astronauts to the orbital laboratory.
Floating in the station's Quest airlock module, Wilmore and Virts switched their spacesuits to battery power to officially begin EVA-29, the 185th spacewalk devoted to station assembly and maintenance since construction began in 1998.
This was the first of three spacewalks by Wilmore and Virts to install more than 760 feet of cabling and to attach new antennas to prepare the space station for eventual dockings by commercial crew capsules. The two additional spacewalks are planned for Wednesday and March 1.
“The challenge for the ISS is going to be continuing maturity over multiple decades of the station and what it will do for crew on the path to commercialization,” said Kenny Todd, International Space Station Operations Integration manager. “It’s fun, it’s exciting and we’re looking forward to transforming the station.”
During Saturday's excursion, the spacewalkers spent most of their time working at the front of the station at the forward end of the Harmony module where a docking port extension known as Pressurized Mating Adapter No. 2 is attached. PMA-2 is where visiting space shuttles once docked and where one of the new IDAs will be attached later this year.
With all of their primary objectives completed, Wilmore and Virts returned to the airlock, ending the spacewalk at 2:26 p.m.
"Really, really nice work today," astronaut Douglas Wheelock called from mission control in Houston.
Saturday's spacewalk was originally planned for Friday, but mission managers delayed it one day in the wake of extensive troubleshooting to verify the health of critical spacesuit components known as fan/pump/separators.
The modules in question use a common motor and drive shaft to power three different components: a fan to circulate oxygen, a pump to circulate cooling water and a system to remove, or separate, condensation from the air supply and return it to the cooling water loop.
Failure of a fan/pump/separator during a spacewalk would stop the flow of oxygen to the astronaut, but an emergency backup system would give the crew member time to return to the station's airlock.
The duo will venture outside the space station again on Feb. 25, to deploy two more cables and lubricate the end of the space station’s robotic arm. NASA TV coverage will begin at 6 a.m. Wednesday ahead of a planned 7:10 a.m. start time for the spacewalk.
Boeing and SpaceX were recently awarded Commercial Crew Transportation Capability contracts with NASA to develop solutions for U.S. astronaut transportation to and from the space station. After NASA crews begin fly with these contractors, it is expected to double the amount of time devoted to science in space from 40 hours to 80 hours per week. U.S. commercial crew capabilities also could provide a faster turnaround to bring completed experiments from the orbiting laboratory back to Earth.
Credit: NASA, cbsnews.com
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Posted: 21 Feb 2015 10:27 AM PST
On Feb. 11, ESA’s Intermediate eXperimental Vehicle (IXV), atmospheric reentry demonstrator, successfully completed its first test flight, ending with a splashdown into the Pacific Ocean and one aerospace company is bursting with pride over the flawless test. “The success of this mission is a source of great pride for us. Thanks to the data collected during the flight, we are paving the way for the development of new-generation reentry vehicles in Europe,” Sandrine Bielecki, Thales Alenia Space spokesperson told astrowatch.net.
Made in Europe
Thales Alenia Space (TAS), a French-Italian joint venture is the prime contractor for IXV, heading a consortium of partners from European industry, research centers and universities. Italy’s significant participation in the project is strongly supported by the Italian Space Agency (ASI).
“Thales Alenia Space took the leadership of the project in December 2009. The IXV was then delivered to ESA in September 2014. Several hundreds of engineers and technicians spread all across Europe worked to the project. Among those, about 120 TAS people were involved,” Bielecki revealed. “The industrial organization of IXV was quite complex. Thales Alenia Space managed a team of about 40 entities - industries, universities, research centers - of 10 countries: Italy, France, Switzerland, Spain, Belgium, Ireland, Portugal, Germany, the Netherlands, and USA. Italy is providing the largest share of funding.”
"With this mission, France and Europe confirm their excellence in space exploration, one of the major challenges facing us in the years ahead," said Geneviève Fioraso, French Minister of Higher Education and Research.
The company is Europe's largest satellite manufacturer and one of the main suppliers to the International Space Station. TAS built the Multi-Purpose Logistics Modules, which was used to transport cargo inside the Space Shuttle orbiters. They also built several modules for the ISS.
Flawless run
IXV lifted off at 13:40 GMT, from Europe’s Spaceport in Kourou, French Guiana atop a Vega rocket. It separated from Vega at an altitude of 340 km and continued up to 412 km. Then, it then began the reentry phase, during which experimental data was acquired via the instruments on the vehicle. The IXV reached a speed during its atmospheric reentry of approximately 7.5 km/sec at an altitude of 120 km, typical of a reentry from low Earth orbit, similar of those of the International Space Station.
“During Flight Phase, the IXV worked perfectly, as the ground segment did, implementing the whole flight program in line with the commanded maneuvers and trajectory prediction,” Bielecki said.
As it descended, the five-meter-long, two-ton craft maneuvered to decelerate from hypersonic to supersonic speed. The entry speed of 7.5 km/s at an altitude of 120 km created the same conditions as those for a vehicle returning from low Earth orbit.
IXV glided through the atmosphere before parachutes deployed to slow the descent further for a safe splashdown in the Pacific Ocean.
At the Advanced Logistics Technology Engineering Center (ALTEC) Mission Control Center in Turin, Italy, specialized technicians followed the mission in real time, coordinating the ground stations during IXV's flight and the naval recovery operations after splashdown.
Bielecki underlines the importance of the test flight and its uniqueness for Europe. “A huge effort was made and our company is now the European benchmark in this sector. It must be noted that a lifting body shape, like the one IXV features, was never flown by Europe,” she said. “Thales Alenia Space plans to further develop its expertise via the European program PRIDE, approved at the Ministerial Conference in December 2014, marking another significant step forward in the understanding the atmospheric re-entry phenomena and in developing critical technologies for reentry systems.“
Destination deep space
Thales Alenia Space is also engaged in developing numerous probes that study other planets in our solar system. The most significant is the next Martian spacecraft made in Europe. ExoMars mission, being built in partnership with Russia is a major challenge for the French-Italian company.
“The ExoMars program is a great scientific challenge and Thales Alenia Space, with a synergistic role between the Turin and Cannes plants, is prime contractor of the Program, looking after the entire design of the two missions (2016 – 2018),” Bielecki noted. “A this time, in Thales Alenia Space Plant in Turin, highly specialized technicians and engineers are integrating the EDM (Entry Descent Module) which, together with the TGO (Trace Gas Orbiter) orbiting module, currently undergoing integration at the Thales Alenia Space plant in Cannes, will make up the vehicle that will land on Mars during the 2016 mission.”
The company is participating in other ESA projects like Euclid, for dark energy and dark matter exploration, Bepi Colombo to explore Mercury, the Service Module of the Orion Crew Transportation System, and even the ISS Exploitation Programme.
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2015년 2월 22일 일요일
Astro Watch
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