The New Horizons spacecraft, slated for a January launch and a decade-long journey to Pluto and Charon, has arrived at Kennedy Space Center for final preparations and testing. This follows a four-month series of tests at Goddard Space Flight Center and the John Hopkins University Applied Physics Laboratory, where the craft was designed and built. What's in the immediate future for New Horizons? The October testing period includes readiness checks, tests of instrument functionality and checks on communications via NASA's Deep Space Network. Hydrazine fuel for attitude control and course correction maneuvers will be loaded in November, and the craft will then undergo a final spin-balance test. A launch countdown rehearsal will be held in November, and in December the spacecraft will be loaded onto the Atlas V rocket that will carry it aloft. Launch is now scheduled for January 11, 2006, with later launch windows available daily between January 12 and February 14.

The Hubble Space telescope used 14 different color filters to dig out the details of different layers in Neptune's atmosphere, showing the haze and clouds in considerable detail, and producing a time-lapse movie that has now been released on the Internet. In the image below (click to enlarge), a natural color view of Neptune appears on the left; the familiar blue-green of the atmosphere is the result of absorption by methane of the red wavelengths striking the planet. At upper right is an enhanced color view. But now check the view at bottom right, taken using methane filters that bring out details above the bulk of the atmospheric methane. At these wavelengths, the planet appears much darker and the long exposure times this permits help to reveal some of Neptune's smaller moons. You can see these in the natural color image, which is a composite of images in green, red and blue light. Clockwise from the top, Proteus is the brightest moon; the others are Larissa, Despina and Galatea....

With excitement building over what everyone hopes will be a January launch of the New Horizons mission to Pluto and Charon, astronomers have found yet another tool for studying the distant worlds. They're taking advantage of a rare alignment in which Charon, Pluto's moon, passes in front of a star. Such an event has been observed only once, some 25 years ago, and with less capable instrumentation. We'll know a lot more about the results of the July 10-11 occultation in September, when they're presented at the 2005 meeting of the American Astronomical Society's Division of Planetary Sciences meeting, to be held in Cambridge, England. There, scientists from MIT and Williams College will report on observations taken with four telescopes located at various sites in Chile. Remarkably, the team was able to muster more than 100 square meters of telescope surface facing Charon, a number that represents a '...noticeable fraction of the world's total telescope area,' according to an MIT news...

Designing a mission to interstellar space is a long-term process. Indeed, NASA's early work on the concept dates back to studies like the Interstellar Precursor Mission developed at the Jet Propulsion Laboratory in 1977, and the later Thousand Astronomical Unit mission, both designed to penetrate as far as 1000 AU into nearby interstellar space. These two missions were envisioned as operating with nuclear-electric propulsion, though solar sails were also under consideration. An early driver for this work was the conference "Missions Beyond the Solar System," held at JPL in 1976. We have yet to develop a fixed interstellar precursor probe design, but the concept continues to evolve. NASA's last interstellar probe review (1999) was based on solar sail technology, but solar thermal, nuclear thermal and nuclear electric propulsion have remained on the table. Now another interesting propulsion alternative has surfaced, using low-thrust but continuous propulsion delivered by a...

The New Horizons mission to Pluto and Charon is on schedule. The spacecraft is now completely assembled and has undergone a comprehensive performance test of its own systems and its seven instruments, according to principal investigator Alan Stern. The first of the major flight mission simulations began at the end of April; this will be followed by another run of performance tests, with environmental testing beginning in mid-May. Eying the January 2006 launch window, NASA plans a readiness review at the end of May. Image: Pluto and Charon are primary targets for this first targeted Kuiper Belt mission. Credit: Johns Hopkins University Applied Physics Laboratory. Stern's contributions to the New Horizons site at Johns Hopkins University's Applied Physics Laboratory are a great way to keep up with the mission's progress. In the latest, Stern recalls how New Horizons got its name: ...as I waited for a streetlight to change near the intersection of Foothills and Arapahoe and looked west...

The so-called 'Pioneer Effect' continues to trigger study. Both Pioneer 10 and 11, as discussed in these pages back in November, have shown changes in their expected trajectories since they moved 20 AU beyond the Sun. In fact, since 1980 radio signals from the Pioneers have been slowly shifting to shorter wavelengths, which seems to imply a slight but interesting deceleration. This has led to at least one proposal for a mission to investigate the Pioneer effect. Both Galileo and Ulysses data have been examined for evidence of a similar effect; while Galileo's data were too limited for use, Ulysses did show a provocative, though extremely slight, change to its own acceleration (though at a much smaller distance from the Sun). Now a new paper notes the difficulties in measuring the Pioneer anomaly, and discusses a way of using asteroids and comets to measure gravitational effects in the outer Solar System. The paper is by computer scientists Gary Page and John Wallin (George Mason...

With the Jupiter Icy Moons Orbiter (JIMO) on hold, NASA is talking to the European Space Agency about a possible joint mission to Europa. A BBC story reports that a prime driver for ESA is the need to use radioisotope thermal generators (RTGs) on the mission, a power source with which the Europeans have little experience. RTGs are needed on missions to the outer planets because they increase the power available to the spacecraft, allowing for a wider range of experiments with more sophisticated instruments. Solar panels remain an option in Jupiter space, but aren't nearly as effective. The other driver, of course, is the recent success of the Cassini/Huygens combined mission, whose stunning images of the Saturnian system and data from the Titan descent and landing have many scientists now thinking of Europa. The moon's cracked ice seems to have been shaped by tidal forces from Jupiter, with reason to believe that an ocean of liquid water might be found beneath an ice crust tens of...

January 11 to February 14, 2006 marks the launch window for NASA's New Horizons mission to Pluto and the Kuiper Belt. At the moment, New Horizons is in pieces, or as principal investigator Alan Stern puts it in an update on the mission, it's in "...boards, boxes and a spacecraft bus on the cleanroom floor at the Johns Hopkins Applied Physics Laboratory..." The high-gain antenna is being checked, and the main computer system installed. According to Stern: The bird also received a guidance, navigation and control software load, and the first testing of the autonomy system (that provides for fault protection) has taken place. Coming soon to the spacecraft are the redundant flight computer, the gyros and the Ralph remote-sensing package. We are now approaching the time - only weeks away - when the last avionics box goes on the spacecraft and New Horizons is dressed in thermal blankets for environmental testing in a large vacuum chamber at NASA Goddard Space Flight Center. New Horizons...