Recent Mid-Infrared Through Submillimeter Observations of Uranus and Neptune
No abstract provided
Hammel, H.↗
Engineering topics
Hammel, H.
Publications and source records attributed to Hammel, H..
The Impact of a Large Object on Jupiter in 2009 July
On 2009 July 19, we observed a single, large impact on Jupiter at a planetocentric latitude of 55 S. This and the Shoemaker-Levy 9 (SL9) impacts on Jupiter in 1994 are the only planetary-scale impacts ever observed. The 2009 impact had an entry trajectory in the opposite direction and with a Tower incidence angle than that of SL9. Comparison of the initial aerosol cloud debris properties, spanning 4800 km east west and 2500 km north south, with those produced by the SL9 fragments and dynamical calculations of pre-impact orbit indicates that the impactor was most probably an icy body with a size of 0.5-1 km. The collision rate of events of this magnitude may be five to ten times more frequent than previously thought. The search for unpredicted impacts, such as the current one, could be best performed in 890 nm and K (2.03--2.36 micrometer) filters in strong gaseous absorption, where the high-altitude aerosols are more reflective than Jupiter's primary clouds.
Sanchez-Lavega, A.↗
Observing Solar System Objects with the James Webb Space Telescope
The James Webb Space Telescope (JWST) will have the capability to observe Solar System objects having apparent rates of motion up to 30 milliarcseconds/sec. The key science drivers are the study of Kuiper Belt Objects, asteroids, comets, and the outer planets and their moons at near and mid-infrared wavelengths. This poster presents the results from a recent study that defined the conceptual design for a capability for JWST to track and observe moving targets. We illustrate about how guide star acquisition and tracking wi11 be handled while retaining the efficient and flexible execution characteristics of JWST event-driven operations. We also show how the JWST pointing control system can readily support moving target observations. The characteristics of Solar System objects that can be observed by JWST are summarized along with descriptions of the major aspects of moving target science observation planning and on-board event-driven execution.
Sonneborn, George↗
Solar System Science with JWST
JWST will enable breakthroughs in our understanding of the physical characteristics of cold bodies in the outer reaches of the Solar System. These objects include Pluto and other Kuiper Belt Objects (KBOs), the icy moons of the giant planets, and distant cometary nuclei. Recent discoveries of large objects in the Kuiper belt, along with many smaller members, make it clear that this region represents a major constituent of our Solar System, one that was hidden until recently because it is so remote and challenging to observe. The near-IR and mid-IR performance of JWST will be unique in its power to probe this region. This poster describes the science drivers for JWST observations of Solar System objects and plans for implementing this capability.
Sonneborn, G.↗
Collision of comet Shoemaker-Levy 9 with Jupiter observed by the NASA infrared telescope facility
The National Aeronautics and Space Administration (NASA) Infrared Telescope Facility was used to investigate the collision of comet Shoemaker-Levy 9 with Jupiter from 12 July to 7 August 1994. Strong thermal infrared emission lasting several minutes was observed after the impacts of fragments C, G, and R. All impacts warmed the stratosphere and some the troposphere up to several degrees. The abundance of stratospheric ammonia increased by more than 50 times. Impact-related particles extended up to a level where the atmospheric pressure measured several millibars. The north polar near-infrared aurora brightened by nearly a factor of 5 a week after the impacts.
NASA Discipline Exobiology↗
Clouds, Hazes, and the Stratospheric Methane Abundance in Neptune
Analysis of high-spatial resolution methane band and continuum imagery of Neptune's relatively homogeneous Equatorial Region yields significant constraints on (1) the stratospheric gaseous methane mixing ratio, (2) the column abundances and optical properties of stratospheric and tropospheric hydrocarbon hazes, and (3) the wavelength-dependent single-scattering albedo of the 3-bar opaque cloud.
Neptune↗