Mass Extinctions and Gamma Ray Bursts

satt fs
Reply Fri 16 Jan, 2004 07:48 pm
The artcle of the first link above continues..

"Without servicing missions, Hubble should continue operating until 2008..

"[T]he telescope - launched in 1990 - has revolutionised the study of astronomy.
"The images it has beamed back to earth have determined the age of the universe - over 13 billion years old - and discovered that a mysterious energy is causing all of objects in the universe to move apart ever quicker, our correspondent adds."

Researches are to be confined to more local region around the Earth, Moon, Mars..(?)
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satt fs
Reply Sat 17 Jan, 2004 11:56 pm
I hope the plan for the Mames Webb Space Telescope, or next generation space telescope, won't be affected. The current development schedule calls for launch in August 2011.

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satt fs
Reply Thu 22 Jan, 2004 05:36 pm
Help for Hubble


"Hubble Space Telescope operators plan to ask Russia for help in keeping the observatory alive and will even consider accepting private donations, which have already been offered."

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Reply Fri 23 Jan, 2004 03:55 pm
Some of you may find path loss confusing as I do. Try this example about a very long space antenna: Transmit one million watts with a perfect very narrow beam antenna. It illuminates one billion square meters at a distance of one light year. That is 1000 square Kilometers. At ten light years range it illuminates 100,000 square kilometers. At 1000 light years it illuminates one billion square kilometers, so your receiving antenna needs an effective receiving area of one square kilometer to receive one milliwatt = 0.001 watts. Modern receivers are much more sensitive than one milliwatt, and the noise level is much lower on most frequencies, so there is no problem sending data 1000 light years except it may be impossible to build a half perfect antenna that produces that narrow a beam even with super conductors and a trillion dollar budget. Let's assume that ET (exactly a thousand light years away) can build the antenna for a trillion dollars, don't mind spending the big bucks and knows on which side of the sun Earth will be in exactly 1000 years. He can send us the data and our one kilometer antenna can receive the data if it is pointing in the correct direction. That is a lot of ifs. The correct direction the receiving antenna points becomes less critical as the transmitting frequency get lower, assuming gil is correct, but the noise increases inversely as the receiving antenna gain.
The probability of building an extremely high gain transmitting antenna at low frequencies = 300,000 HZ = 0.3 megahertz is very low unless ET knows something we don't = likely.
In my hypothesis, extremely high gain transmitting antennas (at multiple light-year range) produce many fast moving hot spots, so several very wide spaced receiving antennas (one AU?) are needed to receive the signal sequentially for more than a second. The hot spots are due to extremely minute antenna jitter, uneven thermal expansion, and minute errors in the shape of the miles wide parabolic dish. Even a person walking softly on an antenna support will produce antenna jitter on the order of nano seconds of arc. Please comment, embellish and/or refute. Neil
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