The orbits of Mars and Earth approach each other about every 2 years. During the most recent near passage, on Oct. 28, the planets came within 69 million kilometers of each other, the closest they’ll come until 2018. A Hubble Space Telescope image taken a day later shows equatorial dust clouds covering an area up to 1,500 km across. NASA scientists say that the likely cause of the clouds was a large dust storm.
Observations by other telescopes indicate that the storm has abated. That’s good news for the twin rovers Opportunity and Spirit, now roaming the Martian surface (SN: 5/28/05, p. 344: Roving on the Red Planet). “We were most concerned about the potential for heavy dust [from the storm] to blot out the sun and decrease the available solar power for the rovers, especially Opportunity, which was closest to the storm,” notes James Bell of Cornell University. “The power did drop a bit from day to day [on Opportunity], but overall, the effect was not dramatic and so we keep rolling on.”