Japan's Akatsuki seems to have missed its rendevouoz with Venus. Credit: Akihiro Ikeshita

It was meant to be a new dawn for Japanese planetary missions, but the disappointing reports from the country's Venus probe Akatsuki are all too familiar.

The Japan Aerospace Exploration Agency (JAXA) reported today that Akatsuki (Japanese for 'dawn') failed to enter the orbit of the searingly hot, rocky planet. Now orbiting the Sun, the probe will have to wait another six years before it has another chance. JAXA has already set up a committee to determine the cause of the failure and examine whether it is worth trying again.

Akatsuki was JAXA's bid to vindicate itself following the failure of its first planetary mission, the Mars probe Nozomi, launched in 1998 to enter the red planet's orbit the following year. That failure was blamed on a faulty valve. Nozomi's next shot at Mars, four years later, also fizzled out (see 'Astronomers try to save Mars probe' and News in Brief item here).

Everything started well for the Akatsuki mission. An H-IIA rocket lifted off on 21 May carrying the probe and the Ikaros solar sail (see 'Japan prepares for Venus countdown'). The latter payload successfully separated, unfurled itself, and has been exciting space scientists since.

Lost in space

On Akatsuki's way to Venus, tests of its various cameras showed everything was in order. In June, JAXA scientists successfully tried out the reverse thrust engines that would try to slow Akatsuki from 37 kilometres per second to the 35 kilometres per second speed it would need to drop into Venus's orbit.

JAXA confirmed that those engines began firing as pre-programmed when Akatsuki drew within 550 kilometres of Venus on 7 June at 08:49 Japan Stanard Time. Plans were for the engines to fire for 12 minutes, during which time the craft was expected to pass behind Venus and temporarily lose contact. Communication was expected to be restored at 09:15. But that didn't happen until 10:29, by which time the craft had entered "safe hold mode", indicating there had been a problem. With tension building in the Sagamihara control centre, the NASA Deep Space Network (DSN), an international network of antennas, began tracking Akatsuki. By 05:00 on 8 December, the DSN had determined that Akatsuki was off course from Venus.

With its five cameras each measuring different wavelengths, Akatsuki was meant to study Venus' surface, clouds and lightning. Complementing the European Space Agency's Venus Express, which has been orbiting Venus since April 2006, Akatsuki promised clues to understanding some of the planet's mysterious features, such as the 'super-rotation' of its atmosphere, which spins at speeds up to 60 times that of the planet itself.

JAXA still doesn't know what went wrong with the ¥25-billion (US$300-million) craft, but it is looking on the bright side. One possibility for Akatsuki's failure to enter orbit is that the engines didn't fire for long enough, and this could mean that it has enough fuel for operations next time around, says Eijiro Namura of JAXA's public affairs office. Namura also says that continuous exposure of the craft's solar panels to the Sun should keep the battery, a major source of concern, in good shape. But he admits that the craft, designed for a two-year mission around Venus, could face various other, as yet unknown, problems.