Japan's space program had remarkably modest beginnings. In a fifteen year time span, they went from rockets that were less than a foot tall and just slightly more powerful than the average model rocket to launching much larger rockets into space and into orbit. The journey to that goal was not that easy, though, as there were many stumbles along the way. That's the history of technology, however; you try, and if you fail, you try again.
It was with ISAS' first orbital rocket that the stumbles really come into play. That rocket was the Lambda 4S series.
The Lambda was the fourth major solid fuel rocket design to come from the ISAS under Professor Hideo Itokawa. It built upon the successes of the earlier Kappa, which was proving to be quite a successful sounding rocket. Like its earlier siblings, the Lambda was a solid fuel rocket, though quite a bit larger. An even larger rocket was being designed to follow the Lambda, the Mu series, which were planned from the outset with satellite launching in mind.
These would be put on hold when it was discovered that with some simple modifications, the Lambda might be able to loft a satellite into orbit. The caveat was that the satellite couldn't be that big. By this point, earlier iterations of the Lambda rocket were being launched. As initially conceived, the Lambda series were designed to probe deep into space, with altitudes of over 1000 miles (1600 kilometers). This is different than an orbital launch, of course, but the potential was there. Professor Hideo Itokawa's team saw this as a means to an end. For them, this was about having the honor of launching the first satellite for Japan.
Indeed, they weren't alone. There were other groups within Japan that sought the same, but Itokawa wanted his team from the University of Tokyo and ISAS to be first. Development of the Mu series was slowed down so that efforts to convert the Lambda into a satellite could commence.
The resulting design was the L-4S.
This was a four stage design, hence the "4" in its designation (the "S" for satellite). To achieve the necessary first stage velocity, the rocket would use two slender solid fuel strap on boosters on the first stage. The complete solid fuel rocket stood just over 54 feet (16.5 meters), making it the smallest and lightest land based satellite launcher ever built. The satellite would physically attached to the fourth stage, a small spherical solid fuel rocket.
But no guidance system would be used for the rocket. This rail launched rocket would use a combination of aerodynamics, gravity, and timing to carry its payload into orbit. The engineer's reasoning had to do with Japan's new constitution, as it was felt that a guidance system could be easily used for military, and potentially offensive, purposes. Rather than take that chance, they chose this simpler approach.
The problem was that while the Lambda sounding rockets were fairly capable, the L-4S was proving not to be. The first attempt to loft a satellite, in September of 1966, failed. So did the next two launches, in December of '66 and April of '67.
The failure of the ISAS team to launch a satellite was proving to be something of crisis for Prof. Itokawa. In addition to the failures, the much more promising Mu rocket was delayed, one that it was hoped could launch a satellite into orbit in 1968. There were also accounting abnormalities at the institute, and the media attention painted the institute in a negative light. Professor Hideo Itokawa resigned as a result.
Before the ISAS could regroup, another problem surfaced, and it wasn't technical in nature. Fisherman expressed concern about the launches being done from Kagoshima. For seventeen months, there would be no rocket launches from the pads at Uchinoura.
Once they resumed, a test launch, L-4T-1, was conducted, and while not perfect, pointed to where the problems existed and what steps needed to be taken.
The fourth Lambda, L-4S-4, was launched in September 1969 to great expectations. Sadly, like the previous L-4S rockets, it, too, failed, the result of a collision between upper stages during separation.
One more attempt would be made.
On February 11th, 1970, the L-4S-5 would launch Japan's first satellite, Ōsumi, would be successfully orbited. It would have a fairly elliptical orbit, with a perigee of 220 miles (350 km) and an apogee of 3,190 miles (5140 km). While it functioned for less than a day (it is speculated that the temperature variations were greater than expected, thus leading to battery failure), this almost 53 pound (24 kg) satellite gave Japan the honor of being the fourth nation to launch a satellite on an indigenous booster, behind Russia, the United States, and France.
In comparison, the delayed Mu series proved to be far more successful, leading to the MV series that would fly until 2006.
When we look back at the history of the the Lambda series and the events leading to Japan's first satellite, one thing becomes readily apparent, and that is that it really is a human story. The rush for the honor of launching Japan's first satellite actually interfered with work on the more capable rocket design. However, it was just enough to give Japan the lead over the next spacefaring country, China, which would launch its Dong Fang Hong I satellite on April 24th, 1970. A Mu series rocket would finally orbit a satellite on February 16th, 1971, a full year after Ōsumi. One more delay would have placed Japan behind China.
More than anything else, however, the Lambda satellite attempts proved that a small, simple launcher could carry a small enough satellite into orbit. With today's technology, such a small payload could be made to do amazing work.
As for Ōsumi, a combination of gravity and atmospheric drag would eventually bring the long dead satellite down on August 2nd, 2003, more than thirty two years after it placed Japan's space program firmly in history.
|Image courtesy Wikipedia/Rlandman|
(I would like to thank Ed LeBouthiller for technical information, as well as the L-4S drawing. If you would like to read more on the technical aspects of the Lambda satellite launchers, I highly recommend his page on the subject - RL)