In the space exploration racket, there is no sweeter word than “first.” And so it was last night that a NASA spacecraft made an important First in planetary exploration:
“NASA’s MESSENGER spacecraft successfully achieved orbit around Mercury at approximately 9 p.m. EDT Thursday. This marks the first time a spacecraft has accomplished this engineering and scientific milestone at our solar system’s innermost planet.”
We flung the Mariner 10 spacecraft past Mercury in fly-by missions in 1974-75. And Messenger itself did three fly-bys as it got into position for the final “orbital insertion.” Now it is the first space probe to park in orbit around the first rock from the sun.
Rosemary Killen, a researcher at Goddard, is one of the many scientists who will reap rewards from this so-far spectacularly successful mission. Her target is the thin “exosphere” of sodium, potassium, and calcium knocked off Mercury’s barren rocky surface by the “solar wind” streaming from the sun.
If you want all the scientific details, read a short explanation below by Rosemary Killen about her work And also read about some of the instruments that Goddard scientists and engineers helped to put on the spacecraft.
Otherwise, enjoy the slide show of Messenger images, 2004-2011, and an informative video by Tom Watters (below), a geologist in the Center for Earth and Planetary Studies at the Smithsonian Institution. He explains the goals of Messenger.
“I am a Participating Scientist on the MESSENGER mission and a member of the MASCS (Mercury Atmospheric and Surface Composition Spectrometer) team. MASCS is a spectrometer covering ultraviolet, visible, and near-infrared wavelengths. The MASCS ultraviolet and visible channel is designed primarily to observe the exosphere, or the very tenuous atmosphere about Mercury, by scanning over selected, diagnostic wavelength ranges.
“Our goals are to determine the composition of the exosphere (which is only partially known at present), and, over the mission lifetime, to determine its spatial and temporal variability. We do this by observing emission lines from atoms (and a few ions) in the exosphere above Mercury’s surface. In so doing we hope to determine the processes that eject atoms from the surface into the exosphere and that lead to the loss of material from the Mercury system.
“Important factors include the relationships among the exosphere and the solar ultraviolet flux, the solar wind and interplanetary magnetic field, and the planet’s intrinsic magnetic field. We hope to be able to determine the effects (if any) of meteor streams that may intersect Mercury’s orbit.
“One intriguing question is the nature of the deposits seen by Earth-based radar (specifically that at the Arecibo Observatory) in polar craters on Mercury, and what that tells us about the sequestration of volatiles. The visible and near-infrared channel of MASCS is primarily designed to measure the reflectance spectrum of the surface in order to determine the mineralogy of surface materials. Ultimately the goal is to unravel the history of the planet: its origin and evolution to the state it occupies today.”
OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.