The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and ...composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.
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The atmosphere of Pluto as observed by New Horizons Gladstone, G. Randall; Stern, S. Alan; Ennico, Kimberly ...
Science (American Association for the Advancement of Science),
03/2016, Volume:
351, Issue:
6279
Journal Article
Peer reviewed
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is ...consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales.
NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick ...layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.
Launched on August 3, 2004, MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) will be the first spacecraft
to orbit the planet Mercury. Designed and built by The Johns Hopkins ...University Applied Physics Laboratory in conjunction
with the Carnegie Institution of Washington, MESSENGER will study Mercury during a 1-year orbital phase that will begin in
March 2011. Currently the spacecraft is in the middle of a 7-year cruise phase that so far has included a flyby of the Earth
(August 2005), two flybys of Venus (October 2006 and June 2007), and the first of three flybys of Mercury (January 2008).
The January 2008 Mercury flyby marked the first spacecraft visit since Mariner 10 (1975) and made MESSENGER the first spacecraft
to encounter Mercury when near the planet’s perihelion. This paper will provide an overview of the thermal design challenges
for both the cruise and orbital phases, the solutions implemented to resolve those challenges, and the flight temperature
and power data that verify the performance of the thermal control subsystem over the mission to date.
A Mercury orbiter mission is challenging from thermal and mass perspectives. The Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission overcomes these challenges while ...avoiding esoteric technologies by using an innovative approach with commonly available materials, minimal moving parts, and maximum heritage. This approach yields a spacecraft with good margins in all categories and low technical risk. The key concepts are a ceramic-cloth sunshade, an integrated lightweight structure and high- performance propulsion system, and a solar array incorporating optical solar reflectors (OSRs). The sunshade maintains the spacecraft at room temperature. The integrated structure and propulsion system provides ample mass margin. The solar array with OSRs, which has already undergone significant testing, provides thermal margin even if the panels are inadvertently pointed directly at the Sun at 0.3 AU.
0.3
AU
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6.
The MESSENGER Spacecraft Leary, James C; Conde, Richard F; Dakermanji, George ...
Space science reviews,
8/2007, Volume:
131, Issue:
1-4
Journal Article
Peer reviewed
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was designed and constructed to withstand the harsh environments associated with achieving and operating in ...Mercury orbit. The system can be divided into eight subsystems: structures and mechanisms (e.g., the composite core structure, aluminum launch vehicle adapter, and deployables), propulsion (e.g., the state-of-the-art titanium fuel tanks, thruster modules, and associated plumbing), thermal (e.g., the ceramic-cloth sunshade, heaters, and radiators), power (e.g., solar arrays, battery, and controlling electronics), avionics (e.g., the processors, solid-state recorder, and data handling electronics), software (e.g., processor-supported code that performs commanding, data handling, and spacecraft control), guidance and control (e.g., attitude sensors including star cameras and Sun sensors integrated with controllers including reaction wheels), radio frequency telecommunications (e.g., the spacecraft antenna suites and supporting electronics), and payload (e.g., the science instruments and supporting processors). This system architecture went through an extensive (nearly four-year) development and testing effort that provided the team with confidence that all mission goals will be achieved.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU
, a cold classical Kuiper Belt object approximately 30 ...kilometers in diameter. Such objects have never been substantially heated by the Sun and are therefore well preserved since their formation. We describe initial results from these encounter observations. MU
is a bilobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color or compositional heterogeneity. No evidence for satellites, rings or other dust structures, a gas coma, or solar wind interactions was detected. MU
's origin appears consistent with pebble cloud collapse followed by a low-velocity merger of its two lobes.
Spacecraft Packaging Schaefer, Edward D; Bailey, Vincent L; Ercol, Carl J ...
Johns Hopkins APL technical digest,
01/2008, Volume:
28, Issue:
1
Journal Article
Peer reviewed
A spacecraft designed for an interplanetary mission is like any highly integrated system and adheres to the basic principle that 'form follows function.'The configuration of an interplanetary ...spacecraft is largely driven by its instruments and their fields of view, pointing, mass, and power and thermal requirements. This article looks at three recently launched APL spacecraft - New Horizons, MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), and STEREO (Solar TErrestrial RElations Observatory) - in the context of their design constraints, how these constraints were met, what areas they had in common, and what areas were unique and why.
Thermal design of NEAR Ercol, Carl J; Krein, Stephen J
Johns Hopkins APL technical digest,
04/1998, Volume:
19, Issue:
2
Journal Article
Peer reviewed
Because of its externally mounted sensors, tight power budget, and widely varying mission conditions, the Near Earth Asteroid Rendezvous (NEAR) spacecraft presented a challenging thermal design ...opportunity. This article describes the design approach, problems encountered in the design process, and final thermal design. Spacecraft testing and early mission performance are also discussed. (Author)
The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft was launched in 2004 and will be inserted into Mercury orbit in March 2011 for one year of orbital operation. ...The large solar distance variations from 1 AU near Earth to 0.3 AU near Mercury impose severe requirements on the solar array design. The solar cell strings were placed between Optical Solar Reflector (OSR) mirrors with a cell to OSR ratio of 1:2 to reduce the panel absorbance. Thermal control is performed by tilting the panels away from normal incidence with increased solar intensity. To minimize the development cost and risk to the program schedule, the approach taken was to avoid the development of new materials and processes but rather to extend the use of existing proven materials and processes. Extensive cell characterization and panel testing were performed successfully to demonstrate meeting the worst-case predicted environments during the mission
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