Slashdot Mirror
New Images from Galileo
deglr6328 writes "New images of Jupiter's Moon Io, along with a false color image of the first isolated ammonia ice cloud discovered on Jupiter; were released yesterday on the Galileo Probe homepage. The probe is currently transmitting back (at it's maximum transmission rate of about 120 Bits per second!) data on previously recorded observations of Ganymede, Jupiter's main ring, Europa and the Jovian Aurorae. Magnetometer measurements that are now being taken in a 100 day survey of Jupiter's huge magnetosphere will be used in a joint investigation with the Cassini spacecraft, which will be making it's closest approach to Jupiter in about two months. After a broken antenna, 5 years in the Jovian environment, 2 extended missions and a total dosage of nearly 4 times the designed radiation exposure, Galileo is still doing spectacular science."
The reason for the low bitrate is the fact that they are not using the main antenna, which failed to open long ago. Instead the engineers ingeniously reprogrammed the craft to use a low-gain antenna to transmit scientific data. The high-gain antenna was meant to transmit 134,400 bits per second (about one imaging frame per minute). Many software tricks had to be applied, as well as the use of better receiving equipment on earth, for the mission to continue as planned. Prior to the software upgrades, the low-gain antenna had a bitrate of only 8-16 bits per second! See http://www.jpl.nasa.gov/galileo/hg a_f act.html.
http://minduploading.org
Alright, before I hear any more complaints about the data rate, keep in mind that Galileo is 50 light minutes from Earth. It's one thing to get 100Mbps over twisted pair copper between machines a kilometer apart, but quite another to do it by radio over about 900,000,000 times that distance (by some quick back of the envelope calculations) with a broken antenna.
Bottom line: don't mess with NASA -- chances are one of their engineers wrote your network driver.
Corgha