After landing on July 4, 1997, Mars Pathfinder returned the first surface pictures of Mars since the Viking mission 21 years earlier. In 30 days of operation, it obtained 9,669 images as well as atmospheric data. The high citation rates stem from the huge excitement created by the landing, with half a billion web hits during the mission.

   Paper #2, from a team led by Peter Smith of the University of Arizona, is a stunning visual feast: Science included a special fold-out section of the best panoramas, and with the use of red/blue glasses the 3D topography (created by Larry Sodorblom of the U.S. Geological Survey) snaps vividly in place. In #2 you’re looking at a landscape 2 billion years old where ridges and troughs are silent witness to catastrophic floods that once swept this area. The stereo view is of shallow gullies about 5m deep, spaced 25m or so apart.

   In paper #5, mission scientists present the overview of the site selection, landing, deployment of the Rover, and the initial findings. The surface is a depositional plain with 16% of the area covered by rounded pebbles, cobbles, and boulders. Large rocks appear perched on the surface as if stranded by flood. The varied rock compositions include high silica content (which would require crustal differentiation), lower silica examples that appear rich in sulfur, and vesiculated fragments that may be volcanic. On the lander itself, red magnetic dust was deposited over time, suggesting that iron was dissolved out of its materials by an active hydrological cycle on Mars.

   As Peter Smith tells Science Watch, "the Pathfinder vision of the surface was not unexpected, and little seen at the site conflicted with the previous understanding that we gleaned from the Viking landers. For instance, the atmospheric properties were essentially the same, and so was the true color. Paper #5 points out remote sensing predicted most of the ground observations: percentage rock coverage, rock sizes, dust coverage, and average slopes." Atmospheric scientists, in #7, also report findings that differ from the Viking results only in detail.

   Science Watch asked Smith about the new science. "These unique views from the surface are of tremendous interest to those following the paradigm-breaking science that is coming from the Mars Global Explorer orbiter. Martian science is undergoing a complete re-write and the graduate textbook used for the past 10 years is now obsolete." This water-rich planet may be more Earth-like than we thought, with a warm wet past in which liquid water flowed and the atmosphere was thicker.

   It is rare to find a "data hypercube" like #10 in the Physics cohort. This report describes a huge radio sky survey conducted at 1.4 GHz by the National Radio Astronomy Observatory (NRAO). Covering 82% of the sky, its haul of 2 x 10⁶ sources is more than all other radio surveys combined. For Science Watch, NRAO’s Jim Condon point out that "most of these sources are produced by supermassive black holes in extremely distant galaxies and quasars. Their nearly isotropic distribution shows that the universe is uniform on the largest scales."

   Condon adds that "objects in the survey also include radio stars, pulsars, and planetary nebulas in our Galaxy, nearby spirals and elliptical galaxies, giant radio sources and gravitational lenses." Any reader of Science Watch who wants to switch to radio astronomy and cosmology will find the entire data set and user software on the web.

   Cosmologists interested in particle physics will check out #3 from the Super-Kamiokande Collaboration, the Japan-U.S. neutrino detection experiment. A 535-day exposure to neutrinos produced in the atmosphere by cosmic rays produced a deficit of muon neutrinos. The data are consistent with a two-flavor oscillation of muon neutrinos to tau neutrinos, which would have profound implications for particle physics and astrophysics.

   Laser diodes (LDs), topic of #6, are used in everything from optical communications systems to compact disk players. These applications have been limited, however, by the lack of materials that can emit blue light efficiently. The shorter the operational wavelength, the tighter light can be focused. A digital versatile disc (DVD) would have a storage capacity of 20 Gb using violet light from a nitride-based III-V semiconductor. In 1995 physicists at Nichia Chemical Industries succeeded with the first violet pulsed LD and achieved continuous operation in 1996. Paper #6 describes the structure and characteristics of the LDs which achieved continuous operation.