The space shuttle Columbia was rolled out to the launch pad June 12 for the reflight of April's shortened microgravity science mission, but the replacement of thermal tiles on part of the orbiter may delay the mission from its scheduled July 1 launch.
      Technicians are replacing three dozen thermal tiles near the nose of the shuttle after tests of other tiles showed that they could crack while in orbit. Similar tiles on the other three orbiters will also be replaced.
     Shuttle managers estimate that the repairs will be done by June 28, just before the countdown is set to begin for the July 1 launch. "The schedule we have laid out says we can meet the July 1 launch date, but it's very tight," said NASA spokesman Joel Wells.
     The mission, STS-94, is a reflight of April's STS-83 microgravity science mission. That flight was cut short after comleting only four days of its sixteen-day mission when one of the shuttle's three fuel cells lost voltage and was shut down. NASA is using the same crew that flew in April and flying the same experiments.
     If Columbia launches on July 1, it will set a new record for the fastest turnaround of the shuttle in the post-Challenger era: 84 days.

An Ariane 4 booster launched two communications satellites into geostationary orbit on June 3 while the Chinese long March booster continued its comeback with the successful launch of a domestic weather satellite June 11.
     An Ariane 44L lifted off from Kourou, French Guiana at 7:20pm (2320 UT) on Tuesday, June 3. It successfully placed two communications satellites, Inmarsat-2F4 and Insat-2A, into geostationary orbit.
     Inmarsat will be used by the International Maritime Satellite Organization to provide mobile communications using laptop-sized terminals on ships, plans, and trucks in the "Atlantic Ocean" region.
     India will use the Insat-2A satellite to provide telecommunications within India and with neighboring countries. India elected to build its own satellite rather than purchase an American or European one because an outside satellite would have required them "to pay another 25 to 30 percent more," one Indian official reported.
     A Long March 3 launched the Fengyun weather satellite on June 11 from the Xichang launch center in southwest China. The launch was the second successful one for the Long March in as many months, and marks a comeback for the troubled booster, which suffered a series of launch explosions and other problems the last two years.

Four aerospace companies, including industry leaders and new startups, have been selected by NASA to receive awards to develop plans for low-cost methods for launching small payloads.
     NASA announced June 9 that Aerojet-General Corp., Pioneer Rocketplane, Summa Technology Inc., and Universal Space Lines Inc. have won study contracts to develop their business and technical plans for small launch vehicles.
     The awards are the first step of NASA's "Bantam" program. The goal of the program is to develop a launch vehicle capable of placing 180 kg (400 lbs.) into orbit for just $1.5 million, less than a quarter of current launch costs for such a payload.
     "This project is identifying and developing low-cost component technologies that can reduce costs and make space transportation affordable," said program manager Garry Lyles. "Now we're looking for ideas for actual launch systems that would incorporate these technologies."
     Over the next six months, the winning companies will develop business plans that will show how much interest there would be in commercial launches of small payloads and conduct technical studies of their proposed vehicle. The sum of the contracts awarded to the four companies is about $8 million.
     After those studies are complete, NASA will select up to two designs for $30 million contracts to build the launch system.
     Pioneer Rocketplane is expected to propose its planned Pathfinder reusable launch vehicle. The Pathfinder would take off like a jet, pick up a load of rocket propellant in a mid-air refueling, and then fly a suborbital trajectory, releasing a payload and rocket stage before flying back to Earth.
     A source with Pioneer Rocketplane said the other three proposals in the Bantam program appear to be expendable rockets. One of those those companies, Summa Technology, is closely tied to industry giant Lockheed Martin.

NASA has given Boeing and Lockheed Martin each $1 million contracts to study the possibility of replacing the shuttle's solid rocket boosters with liquid-fuel versions that would fly back to Earth under power for reuse.
     NASA hopes the Liquid Fly-Back Booster (LFBB) will increase safety, allow the shuttle to lift heavier payloads, and reduce time spent between missions preparing the boosters.
     "It's an idea whose time has come," said John McLuckey, executive vice president of Boeing Defense and Space Group.
     The proposed LFBB system would superficially resemble the current solid-fuel boosters. The boosters would detach from the shuttle nearly three minutes into the mission, about 40 seconds later than the SRBs. Instead of parachuting into the ocean for recovery, though, the LFBBs would glide for nine minutes before starting a set of jet engines for a powered landing on a runway.
     The combination of increased power and better reusability is expected to save up to $500 million a year under current launch rates, according to a Boeing estimate.
     The LFBB would also allow for increased launch rates. Kennedy Space Center Roy Bridges, speaking last month at the International Space Development Conference in Orlando, identified the LFBB as one key element in NASA's plans to eventually double the shuttle launch rate.
     NASA will make a decision on the preliminary design phase of the booster system in early 1998. The first shuttle launch using the new boosters could take place as early as 2002.