Five years late, low on fuel and with its heating system on the blink, Japan’s first Mars-bound probe, the $88 million Nozomi, or “Hope,” appears to be in serious trouble. Mission controllers trying to keep the mission alive face a major test Thursday, when Nozomi is scheduled to make its second swingby of Earth. The maneuver is intended to use the Earth’s gravity as a slingshot to send the probe on its final trajectory to Mars. Experts admit the probe is limping.