Update, 10pm ET: NASA has announced that "There was no hardware or software fault. The underlying cause was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for flyby." Science operations are set to resume on July 7.

Original story:

In nine short days, NASA’s New Horizons spacecraft will make history by becoming the first spacecraft to fly past Pluto. Unfortunately on July 4, just days before the team was to send the approach command to the vehicle, an anomaly occurred at 1:54pm EST and communications with the spacecraft were lost. Communications were quickly restored through the deep space network (DSN), with signal confirmation at 3:15pm EDT.

The spacecraft’s autonomous autopilot recognized a problem and switched from the main to the backup computer—as it’s programmed to do. The autopilot then placed the spacecraft in “safe mode,” and commanded the backup computer to reestablish communication with Earth. New Horizons then began to transmit telemetry to help engineers diagnose the problem.

At this point, there's no need to worry. The New Horizons spacecraft is healthy and will likely remain in safe mode until normal operations mode can be restored. But during this time, no science data can be collected.

Two-way communication with the probe takes nine hours, so the probe may remain in safe mode for a few days while the problem(s) are sorted out. Luckily, New Horizons has completed all course correction maneuvers and was not scheduled to collect any images on July 4. A few were scheduled for July 5 and only one for July 6—none of which are critical to navigation plans.

But photos have been a major feature of New Horizons’ approach to Pluto. As the distance with the dwarf planet has shrunk, we’ve been able to resolve surface features and collect some preliminary data.

After scanning the system over the past few weeks, the science team has not discovered any new moons, nor have they seen evidence that Pluto has rings. However, New Horizons’ infrared spectrometer has confirmed the presence of methane. No, there aren’t cows on Pluto, but there are frozen methane deposits on its surface. In 1976, Earth-based astronomers first observed methane on the dwarf planet, and now we have the data to confirm it. The methane—a colorless, odorless gas present underground and in our atmosphere—found on Pluto could in fact be leftover from the formation of the Solar System over 4.5 billion years ago.

“We already knew there was methane on Pluto, but these are our first detections,” said Will Grundy, the New Horizons Surface Composition team leader with the Lowell Observatory in Flagstaff, Arizona. “Soon we will know if there are differences in the presence of methane ice from one part of Pluto to another.”

Until recently, the only images of the dwarf planet were in black and white. With the release of the first color images, and now the first color map, we can see that Mars may not be the only red planet. Scientists have known for decades that Pluto is reddish brown; however, now we can see it in detail and in living color. Although Mars and Pluto have similar hues, they are due to two very different reasons. Mars gets its red coloring from iron oxide (aka rust). Pluto’s reddish coloration is likely attributed to hydrocarbons formed when cosmic rays and ultraviolet light interact with atmospheric and surface methane.

“Pluto’s reddish color has been known for decades, but New Horizons is now allowing us to correlate the color of different places on the surface with their geology and soon, with their compositions,” said New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado. “This will make it possible to build sophisticated computer models to understand how Pluto has evolved to its current appearance."

Scientists have long postulated that complex hydrocarbon compounds, known as tholins, are created when Lyman-alpha—a particular wavelength of ultraviolet light from the Sun— strikes molecules of methane gas. As a result of chemical reactions, the tholins are formed and drop to ground, forming a reddish gunk that gives Pluto its color. Tholins are found in other parts of the Solar System as well, such as Saturn’s largest moon Titan and Neptune’s largest moon Triton—thought to be a twin of Pluto.

The imaging team combined data from New Horizons LORRI instrument with color data from the Ralph instrument to produce this animation. This is the mission’s first map of the dwarf planet in true color—the color we would see if we were on board the spacecraft.

“Now the unique colors and characteristics of its varied terrains are coming into view," said Simon Porter, a member of the New Horizons Geology and Geophysics team. Added Alex Parker, a member of the New Horizons Composition team, "Pluto's largest dark spot is clearly more red than the majority of the surface, while the brightest area appears closer to neutral gray."

Scientists are expecting to learn more about the cause of Pluto’s reddish tint as New Horizons closes in for its July 14 flyby. Stay tuned as we will be covering the flyby from New Horizons’ mission control center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.