27 September, 2014
For the first time, the American space agency has given control of one of its spacecraft to a team of citizen-scientists. The satellite was launched in 1978 and had not been active since 1997. But the citizen group has found a way to make it useful again.
Space agency scientists have a name for the satellite. It is known as the International Sun Earth Explorer 3, or ISEE-3. ISEE-3 studied space weather beginning in the late 1970s. It also gathered information about particles flowing from the sun. These particles, also known as solar wind, can damage satellites and electrical systems and block radio signals.
In the early 1980s, ISEE-3 was the first satellite to fly through the tail of a comet. A few years later it flew through a much more famous comet -- Halley's Comet. In 1997, the National Aeronautics and Space Administration officially retired ICEE-3; NASA scientists stopped following the satellite closely.
Keith Cowing did not, however. He is a former NASA engineer. And he is one of the leaders of a group called the Reboot Project. The group received permission from NASA to take control of ISEE-3. It got money for the effort from a crowd-sourcing website, a place on the internet where people can give money to projects they support. Mr. Cowing then organized a group of citizen-scientists to take control of the satellite and give it a new purpose.
"Every few years, somebody would, you know, listen to it just as an exercise to see how good their radio telescope was. So, we knew, based on what people were hearing -- ‘cause they were sorta listening as it was gonna come by the Earth -- we knew it was alive, cause if we could hear it, that meant that it had electricity, which meant its solar cells were working and it had two transmitters. So, that's kind of two of the most important things -- you have power and (you were able to) talk to the spacecraft."
But ISEE-3 is not equipped with a computer. So the Reboot Project looked through old records to find ways to communicate with it.
"We'd go through storage units to get documents that people had saved for 30 years. We found the commands and we found people who could write software to re-create the hardware that had been thrown out. And, it was sort of a, a mystery in, in reverse, going back in time and resurrecting (data). We call it techno-archeology."
Mr. Cowing and his team built a new transmitter -- a device that can send signals, or commands. They placed this transmitter on the world's largest radio telescope, at the Arecibo Observatory in Puerto Rico. Soon, they were talking to the satellite. And the satellite was talking to them.
"We had to send tones to the spacecraft to tell it to do things. And we did that on the 29th of May. And we said, in essence, "Respond back!" And it answered back. And OK, well, that's good. That was an accomplishment, ‘cause now we could tell it to do things. And we then sent some additional commands and we eventually started telling it to do things. Which, in essence we were in command of the spacecraft."
But the team had a bigger goal than just talking to the satellite. They wanted to tell ISEE-3 to enter a new orbit around the Earth. When NASA retired the satellite in the late 1990s, scientists told it to travel to the Moon.
"At first we actually got the engines to fire to spin the spacecraft up a little bit, which everybody thought was impossible, but eventually we reached a point where there was a problem with the fuel system that there just wasn't enough gas to, to build up, build up enough pressure to fire the engine. Everything else worked on the spacecraft. It flew by the Moon about 13-14,000 kilometers away. We didn't really change its course all that much. But the difference is it now is sending back science to us."
Years after it no longer had any fuel or battery power, solar cells on the satellite gave it life. Mr. Cowing says that is a lesson for space engineers.
"What we're seeing is, we've been in space for half a century. We've gone from being able to do things close to shore, shall we say, to Earth. Now we've had stuff (satellites) that's been out there for, for decades and that's a different mindset now. We have to start thinking, how can we send probes out there that can last for half a century? And we've got one example of how you can do it."
ISEE-3 worked for so long because its design was so simple.
Mr. Cowing says information from the satellite is free and can be seen online by anyone. ISEE-3 will not be this close to Earth again until 2029.
I'm Christopher Cruise.
This story was reported by VOA science correspondent Rosanne Skirble. It was written for Learning English by Christopher Cruise. It was edited by George Grow.
Words in This Story
satellite – n. a small object in space that moves around a larger object; an object placed in orbit around the earth
block – v. to stop something from being done; to prevent movement
leader/lead – v. to show the way; to command; to control; to go first
control – v. to direct; to have power over
goal – n. that toward which an effort is directed; that which is aimed at; the end of a trip or race
design – v. to plan or create plans for