From the Tomar Re page on Wikipedia:

Tomar's most famous mission while serving in the Corps dealt with the planet Krypton. Krypton, a planet in sector 2813, was growing increasingly unstable. It was due to explode, caused by internal pressures deep inside the planet's core. Tomar-Re sought to use a rare compound called stellarium to absorb some of the tectonic pressure, thus saving the Kryptonians. He gathered the compound, and was en route to Krypton when a yellow solar flare blinded him, and forced him to drop the stellarium. He quickly recovered, but discovered he was blind. He gathered what little stellarium he could without his sight, and proceeded towards Krypton. He was closing in when his vision started to clear. The first thing he saw upon his sight returning was Krypton exploding. The Guardians recovered Tomar and brought him back to Oa, where he healed and rested.

It seems they tried.

@The_Tree: Right on sir, I never saw that.

@DoctorTrips: No problem. I always thought the story of Tomar Re and Krypton was a very interesting one, especially seeing how they link the Green Lantern Corps to Superman's corner of the DCU. Nice Green Arrow avatar too, by the way.

Thanks, I dig the Robot avatar. I never expected it was Tomar who was Krypton's designated Lantern; I was thought it would be like Abin Sur or Sinestro, Tomar never even came to mind.

Dunno if the Tomar Re thing is still in continutity, nothing much was said about it for ages even before Flashpoint or even Infinite Crisis and ive never heard Superman address or acknowledge this story.

@azza04: Eh, I don't see what the point would be in taking it out of continuity, it doesn't really effect much. But, DC has done more stupid things in the past.

@The_Tree: I agree, as far as the story goes it's a bit weak though. If a huge planet is about to blow up why only send one Lantern? where they short staffed that day? I feel that the hole saga of Krypton and Kal-El coming to Earth could have been rewritten to be alot more epicness more intruige and behind the scenes stuff.

@azza04: Yeah, it seems Morrison's been adding a little bit more history to Krypton's destruction. I think it'd be cool if he tackled the Tomar Re story in his usual epic fashion in the pages of Action Comics.

@azza04: Jurisdiction by sector, the gaurdians might not have cared enough to call in the extra muscle, plus Tomar Re's plan seemed pretty fool proof if not for the yellow sun flare

I just done reading a issue of Tales of the Green Lantern Corp annual from 1987 and in there an other planet is experiencing the same thing that happened to Krypton and three other Lantern help the lantern of that sector defuse the destruction. So they can do it it just takes extra muscle, something they learned from Tomar Re