The supermassive star, Eta Carinae, has attracted people\\/s attention with its <br /><br />
picturesque bipolar nebula structure seen in Hubble space telescope images. The <br /><br />
bipolar nebula was produced through an enormous outburst in 1840\\/s when Eta <br /><br />
Carinae became the 2nd brightest star in the sky. This event, which ejected more <br /><br />
than <br /><br />
~10 Msolar, was a signature of large-scale, unstable mass loss episodes at the <br /><br />
end of a massive star\\/s life. <br /><br />
With the advent of space telescopes, Eta Carinae has been observed in great <br /><br />
detail. However, direct emission from the central star has never been detected, <br /><br />
because it is heavily shrouded by the bipolar nebula. Emission from the central <br /><br />
region indicates that Eta Carinae houses a binary system with a highly eccentric <br /><br />
5.5 year orbit, which perhaps comprises an evolved star with ~90 Msolar and a <br /><br />
(possibly) a near-main-sequence O star with ~30 Msolar. Among multi-wavelength <br /><br />
observations, X-ray emission varied dramatically with the orbital period, <br /><br />
showing a flux increase around the periastron passage followed by a strong flux <br /><br />
drop by a factor of 100 for three months thereafter. The flux variation is <br /><br />
basically explained by thin-thermal plasma emission produced by the collision of <br /><br />
winds from the two stars (wind-wind collision: WWC), but the cause of the flux <br /><br />
drop is controversial. The two leading hypotheses are an \\\"eclipse\\\" of X-ray <br /><br />
plasma by the thick <br /><br />
primary stellar wind or a collapse of the WWC plasma. Resolving this problem is <br /><br />
important for solving the process of mass loss from massive stars, and in <br /><br />
finding the property of the component stars. We present the latest view of this <br /><br />
enigmatic object, focusing on the X-ray observations around the last periastron <br /><br />
passage in 2003. We also introduce upcoming campaign observations of Eta Carinae <br /><br />
around the next periastron passage in early 2009. <br /><br />