By Marc Rayman

NASA’s Dawn spacecraft has just arrived at its first target, the giant asteroid Vesta. Each month, Marc Rayman, Dawn’s chief engineer, shares an update on the mission’s progress.

NASA’s Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
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Dear Dawncredibles,

Dawn is now beginning intensive observations of the alien world it orbits. The approach phase, which began on May 3, is complete. Today Dawn is in its survey orbit around Vesta.

Following the previous log, the spacecraft continued using its ion propulsion system to spiral around Vesta, gradually descending to its present altitude of 2700 kilometers (1700 miles). Its flight plan included more observations of Vesta, each one producing incredible views more exciting than the last. Every image revealed new and exotic landscapes. Vesta is unlike any other place humankind’s robotic ambassadors have visited. To continue to share in the thrill of discovery, remember to visit here to see a new image every day during survey orbit. Your correspondent, writing with atypical brevity, also will continue to provide progress reports here at least once a week.

As the ship sailed ever closer to the massive protoplanet during the approach phase, the gravitational attraction grew stronger. We saw in previous logs that astronomers had estimated Vesta’s mass by observing the effect of the 530-kilometer (330-mile) diameter behemoth on distant bodies, including smaller residents of the asteroid belt and even Mars. Now that navigators can detect its pull on nearby Dawn, they are improving that value. Before the explorer’s arrival, Vesta’s mass was calculated to be about 262 billion billion kilograms (289 million billion tons). Now it is measured to be about 259 billion billion kilograms (286 million billion tons), well within the previous margin of error. It is impressive how accurately astronomers had been able to determine the heft of what had appeared as little more than a point of light among the myriad stars. Nevertheless, even this small change of 1.2 percent is important for planning the rest of Dawn’s mission.

› Continue reading Marc Rayman’s August Dawn Journal

By Julie Cooper

Each month in “Slice of History” we feature a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

IBM 360 Computer System — Photograph Number P-24197A

The IBM 360 Model 75 computer system was used for more than 10 years in the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory. It was used in tracking, telemetry, command, monitoring and Deep Space Network operations control for NASA’s Mariner, Viking and Voyager missions. There were two identical computers that could run independently or together, and connected to them were three line printers, two typewriters, a punch card reader and 32 cathode-ray tube (CRT) displays. The system’s main memory had a 1 MB capacity and two disks provided 460 MB of additional storage (less than a standard CD). There were also eight attached magnetic tape units, using seven- and nine-track tapes. From left to right, Ron Sharp, Warren Starr, Larry Hughes, Al Balin, and Dr. George Anderson look on as Jackie Jaramillo shuts down the system for the last time in September 1981, when it was replaced with a newer system. Most of the people shown here were part of JPL’s Communications and Computing Network Services Section.

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.