Student-Built Space Tether Redeemed as Most Successful Yet

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  Space News Business

Student-Built Space Tether Redeemed as Most Successful Yet

By JEREMY HSU
Space News Staff Writer
posted: 31 December 2007
10:28 am ET





New York





A student-built satellite experiment earlier this year shattered records by deploying the longest space tether ever flown in space, but months later the missing return capsule remains a mystery still to be unraveled.







Hundreds of students worldwide watched remotely Sept. 25 as a Russian-built Foton-M3 spacecraft began unwinding a 31.7 kilometer-long




, super-strong space tether that was no thicker than a string. As planned, the experiment’s small Fotino capsule dropped from the Foton-M3




toward Earth, preparing to release at the right moment for re-entry into the atmosphere.

The goal of the experiment was to demonstrate a so-called “space mail” system that would deliver




packages to Earth using just a tether.

But the experiment hit a snag when critical telemetry sensors on the tether deployment mechanism shut down. That left the onboard computer unable to control how quickly the space tether unwound from its spool. Early data suggested the tether reached a length of just




8.5 kilometers




before cutting the Fotino capsule loose.

“We were kind of disappointed by the fact,” said Marco Stelzer, a mission analyst and ground support engineer with the European Space Agency (ESA).

Steizer
joined the Young Engineers Satellite (YES2) experiment, which was




sponsored by the ESA Education Office,




as a university student after seeing




the tether idea promoted by Delta Utec SRC, a private space consultancy




that contracted with ESA. Almost 500 students from Europe, the United States, Russia, Japan




and Australia worked on YES2.





New telemetry data from the Foton spacecraft saved students from a mission cliffhanger, revealing that the space tether deployment had




not slowed




down, as first thought, but actually accelerated.

“Later on, we found out that the tether deployed to its full length, even more than originally planned,” Stelzer said.



Additional data from the U.S. Space Surveillance Network showed that the Foton spacecraft moved close to 1.6 kilometers




higher in orbit when the capsule was cut free. That was to be




expected as the 31.7-kilometer




-long tether’s swinging momentum transferred




to the much heavier spacecraft.





Having smashed the world record for the longest man-made object flown in space, the YES2 team turned its attention to what happened with the Fotino capsule. The onboard beacon had failed to activate and signal the capsule’s final location.



“We have some confidence that the capsule actually came down,” said Stelzer, pointing out that a full-length tether deployment would have released the capsule back into Earth’s atmosphere. A U.S. ground station in Alaska did not detect Fotino flying overhead after the tether release,




suggesting the capsule re-entered the atmosphere instead of continuing along in




low




Earth




orbit with the Foton spacecraft.

“It may have burnt up on re-entry, it may have crash-landed, it may have touched down in difficult terrain somewhere in Turkmenistan, Kazakhstan or Siberia, or its radio beacon did not transmit,”




Roger Walker, YES2 project manager for ESA’s Education Office, said in a public statement. More information will come in the next several weeks from other experiments and sensors onboard Foton.



Whatever Fotino’s fate, the YES2 team cheered the test of the “space mail” delivery system using the space tether – even if the package was lost along the way.



“We proved that tether technology actually works,” Stelzer said.

Future space tethers might not only deliver parcels to Earth, but also swing spacecraft or satellites into different orbits or toward other planets.

The ESA Education Office has additional satellite projects in development, including the European Student Earth Orbiter




planned for 2010 and the European Student Moon Orbiter




planned for 2011.