APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
“If a silicon-based giraffe had walked by, its portrait would have been taken.” - Carl Sagangeckzilla wrote:What could it see that we can't already see from Earth? Unless there is some kind of nearby small object, which there is a very small chance of, there is nothing to look at. And how would we know what way to point the camera if we don't already know something is there? The light from our star is also very dim that far out. I agree with the camera being deactivated. All it would do is drain already limited power.saturno2 wrote:geckzilla
Thanks for your link, very interesting.
It says the cameras of Voyager 2 are unused.
Should activate a camera from time to time in case something unexpected appears
saturno2 wrote:Voyager 2 took photos of Saturn. Uranus and Neptune
This photos are high resolution and very interesting
I have not hand of Jupiter.
Well,but what "see " the Voyager 2, now?
Voyager 1 appears to have at long last left our solar system and entered interstellar space, says a University of Maryland-led team of researchers.
Voyager 1 appears to have at long last left our solar system and entered interstellar space, says a University of Maryland-led team of researchers. Photo source: NASA.gov Carrying Earthly greetings on a gold plated phonograph record and still-operational scientific instruments – including the Low Energy Charged Particle detector designed, built and overseen, in part, by UMD's Space Physics Group – NASA's Voyager 1 has traveled farther from Earth than any other human-made object. And now, these researchers say, it has begun the first exploration of our galaxy beyond the Sun's influence.
"It's a somewhat controversial view, but we think Voyager has finally left the Solar System, and is truly beginning its travels through the Milky Way," says UMD research scientist Marc Swisdak, lead author of a new paper published online this week in The Astrophysical Journal Letters. Swisdak and fellow plasma physicists James F. Drake, also of the University of Maryland, and Merav Opher of Boston University have constructed a model of the outer edge of the Solar System that fits recent observations, both expected and unexpected.
Their model indicates Voyager 1 actually entered interstellar space a little more than a year ago, a finding directly counter to recent papers by NASA and other scientists suggesting the spacecraft was still in a fuzzily-defined transition zone between the Sun's sphere of influence and the rest of the galaxy. ...
A newly published paper argues that NASA's Voyager 1 spacecraft has already entered interstellar space. The model described in the paper is new and different from other models used so far to explain the data the spacecraft has been sending back from more than 11 billion miles (18 billion kilometers) away from our sun.
NASA's Voyager project scientist, Ed Stone of the California Institute of Technology in Pasadena, explains:
"Details of a new model have just been published that lead the scientists who created the model to argue that NASA's Voyager 1 spacecraft data can be consistent with entering interstellar space in 2012. In describing on a fine scale how magnetic field lines from the sun and magnetic field lines from interstellar space can connect to each other, they conclude Voyager 1 has been detecting the interstellar magnetic field since July 27, 2012. Their model would mean that the interstellar magnetic field direction is the same as that which originates from our sun.
Other models envision the interstellar magnetic field draped around our solar bubble and predict that the direction of the interstellar magnetic field is different from the solar magnetic field inside. By that interpretation, Voyager 1 would still be inside our solar bubble.
The fine-scale magnetic connection model will become part of the discussion among scientists as they try to reconcile what may be happening on a fine scale with what happens on a larger scale.
The Voyager 1 spacecraft is exploring a region no spacecraft has ever been to before. We will continue to look for any further developments over the coming months and years as Voyager explores an uncharted frontier."
bystander wrote:
How Do We Know When Voyager Reaches Interstellar Space?
NASA | Solar System Exploration | 2013 Sep 12
http://solarsystem.nasa.gov/scitech/display.cfm?ST_ID=2610 wrote:
<<So, would the team say Voyager 1 has left the solar system? Not exactly - and that's part of the confusion. Since the 1960s, most scientists have defined our solar system as going out to the Oort Cloud, where the comets that swing by our sun on long timescales originate. That area is where the gravity of other stars begins to dominate that of the sun. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Informally, of course, "solar system" typically means the planetary neighborhood around our sun. Because of this ambiguity, the Voyager team has lately favored talking about interstellar space, which is specifically the space between each star's realm of plasma influence.
"What we can say is Voyager 1 is bathed in matter from other stars," Stone said. >>
Wouldn't a space based Ultra-Low Frequency receiver be able to observe radio echoes off of the Heliopausehttp://en.wikipedia.org/wiki/Plasma_oscillation wrote:<<Plasma oscillations, also known as "Langmuir waves", are rapid oscillations of the electron density in conducting media such as plasmas or metals. The oscillations can be described as an instability in the dielectric function of a free electron gas. The frequency only depends weakly on the wavelength. Langmuir waves were discovered by American physicists Irving Langmuir (31 January 1881 – 16 August 1957) and Lewi Tonks (1897-1971) in the 1920s. They are parallel in form to Jeans instability waves, which are caused by gravitational instabilities in a static medium.Click to play embedded YouTube video.
Consider a neutral plasma, consisting of a gas of positively charged ions and negatively charged electrons. If one displaces by a tiny amount all of the electrons with respect to the ions, the Coulomb force pulls back, acting as a restoring force.
If the thermal motion of the electrons is ignored, it is possible to show that the charge density oscillates at the plasma frequency
whereis the number density of electrons, e is the electric charge, m* is the effective mass of the electron, and
is the permittivity of free space. Since the frequency is independent of the wavelength, these oscillations have an infinite phase velocity and zero group velocity.
Note that, if m* is electron mass, plasma frequency depends only on physical constants and concentration of electronswith number density
http://en.wikipedia.org/wiki/Ultra_low_frequency wrote:
<<Ultra-low frequency (ULF) is the frequency range of electromagnetic waves between 300 hertz and 3 kilohertz. Many types of waves in the ULF frequency band can be observed in the magnetosphere and on the ground. These waves represent important physical processes in the near-Earth plasma environment. The speed of the ULF waves is often associated with the Alfven velocity that depends on the ambient magnetic field and plasma mass density.
Some monitoring stations have reported that earthquakes are sometimes preceded by a spike in ULF activity. A remarkable example of this occurred before the 1989 Loma Prieta earthquake in California. On December 9, 2010, geoscientists announced that the DEMETER satellite observed a dramatic increase in ULF radio waves over Haiti in the month before the magnitude 7.0 Mw 2010 earthquake. Researchers are attempting to learn more about this correlation to find out whether this method can be used as part of an early warning system for earthquakes.
Earth Mode Communications
ULF has been used by the military for secure communications through the ground. NATO AGARD publications from the 1960s detailed many such systems. Communications through the ground using conduction fields is known as "Earth-Mode" communications and was first used in WWI. Radio amateurs and electronics hobbyists have used this mode for limited range communications using audio power amplifiers connected to widely spaced electrode pairs hammered into the soil. At the receiving end, the signal is detected as a weak electric current between a further pair of electrodes. Using weak signal reception methods with PC-based DSP filtering with extremely narrow bandwidths, it is possible to receive signals at a range of a few kilometers with a transmitting power of 10-100 W and electrode spacing of around 10-50 m.>>
It Hertz to be away from home.Beyond wrote:
So the more Voyager gets into interstellar space, the louder the screech
But only for a little while.neufer wrote:It Hertz to be away from home.Beyond wrote:
So the more Voyager gets into interstellar space, the louder the screech
http://www.slate.com/blogs/bad_astronom ... space.htmlsaturno2 wrote:I think it is necessary a definition of the diameter of the Solar System.
One universally accepted definition
Phil Plait wrote:I have two things to say here, and I want to be careful. First, this is an amazing event, and well worth celebrating. Second, a lot of people are saying Voyager 1 has left the solar system, and that’s not really accurate.
Never take personal Avis from the Internet.Beyond wrote:But only for a little while.neufer wrote:It Hertz to be away from home.Beyond wrote:
So the more Voyager gets into interstellar space, the louder the screech
According to Hertz.com,
"Joining the Hertz team opens doors to many exciting and challenging opportunities",
so you will forget about all the Hertz you had when you left.
That's good adviceneufer wrote:Never take personal Avis from the Internet.
Avis, tried until they hertz, to be #1, but could never get farther than #2. You might say they pooped themselves out trying. I guess they didn't know as much about the 7th planet back then. http://www.nytimes.com/2013/09/13/science/in-a-breathtaking-first-nasa-craft-exits-the-solar-system.html?pagewanted=all&_r=0 wrote:In a Breathtaking First, NASA’s Voyager 1 Exits the Solar System
By BROOKS BARNES, NY Times, September 12, 2013
PASADENA, Calif. — By today’s standards, the spacecraft’s technology is laughable: it carries an 8-track tape recorder and computers with one-240,000th the memory of a low-end iPhone. When it left Earth 36 years ago, it was designed as a four-year mission to Saturn, and everything after that was gravy. But Voyager 1 has become — thrillingly — the Little Spacecraft That Could. On Thursday, scientists declared that it had become the first probe to exit the solar system, a breathtaking achievement that NASA could only fantasize about back when Voyager was launched in 1977, the same year “Star Wars” was released.
“I don’t know if it’s in the same league as landing on the moon, but it’s right up there — ‘Star Trek’ stuff, for sure,” said Donald A. Gurnett, a physics professor at the University of Iowa and the co-author of a paper published Thursday in the journal Science about Voyager’s feat. “I mean, consider the distance. It’s hard even for scientists to comprehend.” Even among planetary scientists, who tend to dream large, the idea that something they built could travel beyond the Sun’s empire and keep grinding away is impressive. Plenty of telescopes gaze at the far parts of the Milky Way, but Voyager 1 can now touch and feel the cold, unexplored region in between the stars and send back detailed dispatches about conditions there. It takes 17 hours and 22 minutes for Voyager’s signals to reach NASA’s Jet Propulsion Laboratory here. “This is historic stuff, a bit like the first exploration of Earth, and we had to look at the data very, very carefully,” said Edward C. Stone, 77, NASA’s top Voyager expert, who has been working on the project since 1972. He said he was excited about what comes next. “It’s now the start of a whole new mission,” he said.
The lonely probe, which is 11.7 billion miles from Earth and hurtling away at 38,000 miles per hour, has long been on the cusp, treading a boundary between the bubble of hot, energetic particles around the solar system and the dark region beyond. There, in interstellar space, the plasma, or ionized gas, is noticeably denser. Dr. Gurnett and his team have spent the past few months analyzing their data, trying to nail down whether what they were seeing was solar plasma or the plasma of interstellar space. Now they are certain it was the latter, and have even pinpointed a date for the crossing: Aug. 25, 2012.
At a news conference on Thursday, NASA scientists were a bit vague about what they hope to get from Voyager 1 from now on. The answer, to some extent, depends on what instruments continue to function as the power supply dwindles. Dr. Stone expects Voyager 1 to keep sending back data — with a 23-watt transmitter, about the equivalent of a refrigerator light bulb — until roughly 2025. One hope is that Voyager 1’s position will allow scientists to more accurately study galactic cosmic rays, which are high-energy particles that originate outside the solar system. They would use the information to make judgments about what interstellar space is like at even greater distances from Earth.
In its heyday, Voyager 1 pumped out never-before-seen images of Jupiter and Saturn. But it stopped sending home pictures in 1990, to conserve energy and because there was no longer much to see. A companion spacecraft, Voyager 2, also launched in 1977, has stopped sending back images as well. Voyager 2 is moving in a different direction but is also expected to exit the solar system. Eventually, NASA said, the Voyagers will pass other stars, coasting and drifting and being pulled by gravity. The next big encounter for Voyager 1, in around 40,000 years, is expected to be a dwarf star dispassionately known as AC+793888 in the constellation of Camelopardalis. But already, Voyager 1 has achieved what Dr. Gurnett called “the holy grail of heliosphere research.”
Voyager 1 left the solar system the same month that Curiosity, NASA’s state-of-the-art rover, landed on Mars and started sending home gorgeous snapshots. Curiosity’s exploration team, some 400 strong, promptly dazzled the world by driving the $2.5 billion robot across a patch of Martian terrain, a feat that turned the Red Bull-chugging engineers and scientists of Building 264 of the Jet Propulsion Laboratory campus into rock stars. By comparison, the Voyager mission looked like a Betamax in the era of Bluetooth.
The 12-person Voyager staff was long ago moved from the Jet Propulsion Laboratory campus to cramped quarters down the street, next to a McDonald’s. In an interview last month at Voyager’s offices, Suzanne R. Dodd, the Voyager project manager, said that when she attended meetings in Building 264, she kept a low profile in deference to the Mars team. “I try to stay out of the elevator and take the stairs,” Ms. Dodd said. “They’re doing important work there, and I’ll only slow them down.” At 52, Ms. Dodd is a relative newcomer to Voyager, first working on the mission in 1984. Now she and her team seem poised to return to the spotlight.
As the solar system’s edge grew tantalizingly close, NASA asked the Voyager scientists to increase the amount of data collection. The problem: the 8-track data recorders from 1977 were not exactly bursting with extra space. Could Ms. Dodd even find anyone who specialized in that piece of technology and could coax it to record more? “These younger engineers can write a lot of sloppy code, and it doesn’t matter, but here, with very limited capacity, you have to be extremely precise and have a real strategy,” she said. She was able to find her man: Lawrence J. Zottarelli, 77, a retired NASA engineer. He came up with a solution. But would it work? Mr. Zottarelli waited at Voyager mission control one afternoon last month to find out. The first of the newly programmed data dumps was set to come down. Ms. Dodd, Dr. Stone and Mr. Zottarelli watched two old Sun Microsystems computers like children watching for a chick to peck through an egg. “Nine, eight, seven,” Dr. Stone counted down. “Everything’s fine,” said Mr. Zottarelli, flashing a thumbs up. “You’re on your own now.” The relief was written all over Ms. Dodd’s face. “It’s not easy flying an old spacecraft,” she said. Her eyes moved to Dr. Stone, who was peering at a computer through his trifocals. “There are lots of old missions,” he responded with a sly smile. “But not many are doing exciting new things.”>>
