TOKYO -- Japan's first privately developed rocket is set for liftoff, marking a major step toward seizing commercial opportunities in space.
Momo, as startup Interstellar Technologies calls its crowdfunded rocket, is scheduled to head skyward on Saturday between 3:45 p.m. and 5 p.m. local time. The launch site is in Taiki, a small town on the Pacific coast of Hokkaido.
In four minutes, Momo is expected to reach an altitude of 100km -- typically considered the boundary between Earth's atmosphere and outer space. After the flight, the rocket is to fall into the sea 50km from the launch area.
Though Momo will not carry a satellite into orbit this time, Interstellar hopes to launch small ones in the future.
The rocket is based on established, as opposed to cutting-edge, technologies. To keep costs in check, the startup relied on commercially available parts used in ordinary electronics. Likewise, the engine and fuel are not the most advanced types available today, but are nonetheless well-tested in the industry.
The launch was postponed from the spring, due to engine and other problems. "We struggled," said Takahiro Inagawa, Interstellar's CEO. "But in just one year after the first burn test, we managed to improve the engine to achieve the necessary capability."
The issues, Inagawa said, were solved "very quickly."
Flying on ethanol
For fuel, Momo uses a mix of ethanol and liquid oxygen. Ethanol has been used in rockets since the 1940s; Germany employed it in the V2 rocket developed during World War II. Engineers who designed that rocket moved to the U.S., where the technology was used in the Mercury-Redstone launch vehicles, which enabled the first manned space flight by the U.S.
Japan's H-IIA rocket, developed as a national project, uses liquid hydrogen, which burns more easily. But liquid hydrogen is hard to handle: It has to be kept at low temperatures, for example.
Storing ethanol is a lot easier. Its concentration is about the same as water, so that it can be kept in smaller tanks than the ones you need for liquid hydrogen. The concentration of the latter fuel is a fifth of water.
Ethanol is also easy to store because it can be kept at room temperature in liquid form. It easily dissolves in water and is decomposed by microorganisms, making it environment-friendly.
Tetsuo Hiraiwa, who studies liquid fuel at the Japan Aerospace Exploration Agency, says ethanol remains an option for rockets because of the safety and green factors, even though it does not work as well as liquid hydrogen.
Escaping the "valley"
Interstellar also opted for tried-and-true technologies for its engine. It used a structure called a pintle injector, which was adopted for the Apollo Program to smooth the landing of the spacecraft on the moon. The structure has coaxial cylinders; liquid oxygen coming out of the inner cylinder is mixed with ethanol flowing from the outer cylinder.
Hokkaido University professor Harunori Nagata, who has been helping out with commercial rocket development, said Momo's fuel and engine structure suggest the engineers wanted to "make use of outmoded technologies at low cost." But to carry a satellite into space, he said that "the rocket would have to have several engines bundled up and increase the number of stages."
Eventually, Interstellar hopes to go beyond sending small satellites into orbit: It wants to send up humans.
Before startups like Interstellar can think about such giant leaps, they need to make smaller steps -- such as proving that their technology actually works, securing financing and recruiting talent.
"Now the company is in the most difficult phase, which is often called the valley of death [among startups]," said well-known entrepreneur Takafumi Horie, who invested in the Momo project and sits on Interstellar's board.
"If it overcomes that, it will get closer to acquiring the technology needed to launch a satellite."