HOUSTON — The test flight of a potentially revolutionary transportation system for future space missions has been delayed several months for more preflight testing, project officials announced Tuesday. Originally planned for the second half of December, the flight of the Demonstrator-3 inflatable space vehicle will now occur sometime in the spring of 2005.
If the technology proves out, it could fill a crucial gap in future space transportation by allowing objects to be more easily returned from space, surviving the fiery fall through Earth’s atmosphere. Small packets could carry scientific results from the international space station. And when the space shuttle is retired, sometime after 2010, bigger versions could still provide a safe return for large space modules, rocket boosters and other containers.
Russian space engineers funded by the European Space Agency had been quietly preparing a new test of the vehicle. In large part because previous test flights have ended ignominiously, preparations for the latest test were proceeding without any official advance notice, although program officials have privately briefed MSNBC.com on its progress.
Sometimes referred to as a “ballute,” or “balloon parachute,” the technology has for decades been recognized as a potential breakthrough, but sufficiently strong materials had never been available. Also, many top space program managers long felt that the idea of using a balloon instead of a heavy ceramic or metal shell as a heat shield was utter nonsense.
“Technically, inflatables are feasible,” said retired NASA futurist Joe Loftus, who once headed the advanced planning office at Johnson Space Center in Houston. “The question is: What is it that will make them desirable?”
In February 2000, a flight test of what Russian space engineers call the “space parachute” came close to success. The garbage-can-sized hardware flew as a free piggyback payload on the first orbital test of the Fregat, a new upper stage for Russia’s Soyuz rocket. After reaching orbit, the Fregat stage then dove back into the atmosphere.
The Demonstrator-1 payload separated from the upper stage and inflated its ring of balloons. Tracked by Russian air defense radars, the vehicle descended as planned, surviving the extreme temperatures and enduring a maximum force of 15 G’s. It landed near Orenburg in the southern Urals, about 30 miles (50 kilometers) past the aim point. A secondary balloon failure left it somewhat scorched, but intact.
As a last-minute add-on test, engineers also strapped a larger inflatable shield around the base of the Volkswagen-sized Fregat stage itself. This second unofficial test also worked, up to a point. The balloon-shielded vehicle safely passed through the atmosphere, as tracked on Russian radars, but landed far off course in a snowstorm. Months later, searchers found the crash site, but scrap metal scavengers had apparently loaded the rocket on a truck and hauled it off, leaving behind the deflated heat shield.
Looking for other bargain basement space boosters, the project then switched to the Volna missiles being launched from submarines in the Barents Sea. One launch in August 2001 failed when the booster hardware did not release the payload, which was never even given a name. A second flight, on July 12, 2002, had the opposite problem — the Demonstrator-2 payload fell off the second stage while it was still firing, and fell to Earth far off course.
Latest plans delayed
Lidia Avdeyeva, the press secretary of Moscow's Lavochkin production and science association, disclosed the delay of the latest test on Tuesday.
"The participants in the projects — the Lavochkin association, the European Space Agency and the European aerospace concern EADS-ST — have decided to postpone until the spring of the next year the launch of the pneumatic braking device that was planned for December," she told journalists. "It has became clear during the preparation of the device for the launch that additional tests of it are necessary for increasing the reliability of the launch."
As with the two previous tests, this mission is to be sent up on a converted Soviet-era missile launched from a submarine cruising in the Barents Sea, north of Arkhangelsk. If all goes as planned, it will land safely in a test range on Kamchatka Peninsula in the Russian Far East, half an hour later.
Before it enters the atmosphere, the balloon is to be inflated by nitrogen, taking on the appearance of a badminton shuttlecock. Special heat insulation would protect the cargo from a temperature of up to 10,000 degrees Fahrenheit (6,000 degrees Celsius).
If it works…
The European Space Agency is funding the tests in hopes of developing an independent means of getting scientific payloads back from space without having to rent cargo space on NASA's space shuttles. Such a capability also could have been used during the current grounding of the shuttle fleet, as well as in the future when the shuttle are retired.
Even bigger variants could be built, to support the return of payloads weighing "tens of tons," Avdeyeva said. The device could be used not only for cargo recovery but also for the emergency evacuation of space station crews, she added.
Stephan Walther, a project scientist in Bremen, Germany, hopes that a string of successes will eventually persuade ESA to pay for a full-up cargo system and even consider inflatable lifeboats.
American space engineer Robert Kendell Jr. told MSNBC.com that his company, Aerospace Recovery Systems, has patented several designs for inflatable air-drop systems. His father worked on inflatable space bailout designs in the 1960s, and the two men continued to publish scientific papers advocating the use of inflatables for orbital re-entry.
The elder Kendell said the company sent a proposal to the Air Force for test flights, but “no one was interested enough to fund it.”
NASA's plan to retire the shuttles has provided a new opportunity to consider the use of inflatable recovery systems. In an email to MSNBC.com, the younger Kendell said his company's system could handle the re-entry of a 17,000-pound (7,700-kilogram) payload from the space station, measuring 15 feet in diameter and 20 feet in length (4.5 by 6 meters). He said bringing such a cargo back to Earth would require a paper-airplane-shaped inflatable glider, 18 feet (5.5 meters) wide in front and 72 feet (22 meters) wide at the tail.
“Maximum temperature would be about 1,800 degrees F,” he wrote, with a maximum force of 10 G's. Kendell said it would be a somewhat rougher ride home than in a shuttle payload bay — but it would be a reliable ride.