BY YASUHARU TANAKA AND RINTARO SAKURAI
THE ASAHI SHIMBUN
Excitement among academic teams and businesses over their expanded role in Japan's space program has already been tempered by the almost inevitable technical problems that afflict satellites in space.
On Jan. 23, an H-2A rocket launched six small piggyback payloads built by university researchers and businesses, together with a seventh created by the Japan Aerospace Exploration Agency. Of the first six, four have been beset by problems. Only two have passed tests by teams on the ground.
One is the Maido-1 satellite, developed by a group of small businesses in Higashi-Osaka, Osaka Prefecture, and used to observing lightning.
The Prism satellite, developed by a group at the University of Tokyo, also passed tests on its telephoto lens, which is capturing high-resolution images of the Earth.
There has been no contact with the Kagayaki satellite developed by Sorun Corp., a systems development company.
The SPRITE-SAT developed by Tohoku University was supposed to observe the sprite, a transient luminous event in the upper atmosphere induced by lightning. But on Feb. 4, after a rod was extended to measure electromagnetic waves, the satellite stopped responding to commands from Earth.
Kazuya Yoshida, a professor of aerospace engineering at Tohoku University, likened it to "a situation when a computer screen freezes. But since the satellite is in outer space, we can't simply press the reset button."
After determining the cause of the problem, researchers will attempt to restore the satellite by sending out commands in powerful radio waves.
The KKS-1 satellite developed by the Tokyo Metropolitan College of Industrial Technology has also failed to respond to commands from Earth.
Tomohiro Ishikawa, an associate professor of electrical engineering at the college, said, "The computer program isn't operating normally and the battery has stopped functioning because of lower-than-expected temperatures."
The STARS-1 satellite, developed by a team at Kagawa University, had planned an experiment to control a daughter satellite after separating it from the mother satellite to which it was tethered--but the tether has not extended as planned.
The failures are not an indication of technological ineptitude.
In fact, Shinichi Nakasuka, a professor of aeronautics and astronautics who is leading the Todai satellite project, said: "On a global level, Japanese institutions show a high level of technological prowess. About half of the small satellites developed by universities overseas fail to receive electric signals after launch."
Of the 15 satellites that have been developed by Japanese educational bodies and businesses, Kagayaki is the only one that did not receive a signal from the outset, excluding satellites payloaded on failed rocket launches.
The small size of the satellites makes it impossible to include backup CPUs and alternative power sources, and is one factor behind the difficulties.
Masahiro Nohmi, an associate professor at Kagawa University who is involved in the STARS-1 project, said, "Due to the small size, the configuration of the satellite has become more complicated and it has been more difficult to use all the functions."
The extreme conditions of outer space--the vacuum state, cosmic radiation and sudden changes in temperature, among other things--also take a toll.
The vacuum state can cause metals to stick together, and disable motors and valves. It can also make it more difficult for the satellite to release heat, causing electronic parts to overheat.
Saburo Matsunaga, an associate professor of mechanical and aerospace engineering at the Tokyo Institute of Technology, said cosmic radiation could trigger electric current surges or electric discharge that could, in worst-case scenarios, damage computer circuits.
Tokyo Tech teams have created three satellites. The second satellite developed problems with its CPU as a result of cosmic radiation and stopped responding to commands about a month after launch.
Based on that experience, the third satellite included a function that automatically shuts off the power source when a electrical surge is detected.
Matsunaga said, "You have to use your imagination to be able to cover whatever problems may arise in a state of limited conditions. Detailed consideration becomes especially important if you want to create successful small satellites."
Despite the setbacks, academic teams have not been deterred.
The most ambitious project under way is being put together by 20 educational teams from the University Space Engineering Consortium (UNISEC), which comprises more than 40 research teams from institutes of higher education: In the summer of 2010 they plan to launch the UNITEC-1 satellite, which will set out to take photos of the surface of Venus. It will be the first attempt by academics to make a satellite that can leave the gravitational pull of the Earth and moon.
To develop the satellite, UNISEC broke up into teams of two to four educational bodies. Each team set to work on a particular aspect of the satellite, such as operations, communications and computers.
Not only does that allow the various bodies to focus on their strengths, it also reduces the time and expense they have to expend.
They also compete against one another. An experiment scheduled for this summer will select five or six computers that can withstand heat and vibration tests.
Todai's Nakasuka, who heads UNISEC, said, "I want this to become a step to improving the work done at universities and other educational bodies so they can fulfill their role in Japan's space exploration efforts."(IHT/Asahi: March 31,2009)