William Sheehan - The Planet Mars: A History of Observation and Discovery

Twenty years after Viking we are finally going back, with no fewer than ten missions planned for the period between 1996 and 2003. In November 1996, the American Mars Pathfinder (APF) is scheduled for launch. If all goes well, it will land in July 1997 at the Ares--Tiu Valles outflow channels (19.5 N, 32.8 W) and will deploy a small robotic rover called Sojourner to explore the Ares Vallis floodplain---a site, incidentally, very close to that originally planned for the Viking 1 landing in 1976.

Mars Global Surveyor (MGS) an orbiter scheduled for launch at the same time, will arrive in Martian orbit in August 1997 and will begin mapping the planet in January 1998. A Russian mission consisting of an orbiter and two landers will at Mars in October 1997.

It is likely that human explorers will follow eventually---perhaps as soon as the middle of the twenty-first century. If and when they do, they will owe much to the Mars of romance, to Schiaparelli, Lowell, Wells, Burroughs, and the rest. We have only now begun to awaken from our dream of Mars, the fire opal we have so long sought through our telescopes, to see it as it really is. The warm hues of the Martian deserts prove to be as deceptive as the pure polar pink of an Arctic sunset, and belie the really terrible reality. Their apparent warmth is only that of our imaginations, which they have so long fired. Still, with its great volcanoes, canyons, and dry riverbeds, Mars remains a fascinating, even if a lifeless, world. And its exploration has only just begun.

The table below gives the opposition date, the planet's position in the sky in terms of its right ascension (RA; hour angle from the first point of Aries) and its declination north or south of the equator (the latter is particularly important because, for northern observatories, a far southerly declination interferes with observation of the planet, which must then be viewed through a longer path of the Earth's atmosphere); the apparent size of the disk in seconds of arc; and the distance of the planet in astronomical units (1 a.u. = Earth-Sun distance). Owing to the slight inclination of Mars's orbit to that of the Earth, the minimum separation between the two bodies can actually occur a few days before or after the opposition date.