Belt Mission Research Articles

TugSat: Removing Space Debris from Geostationary Orbits Using Solar Sails

Space debris accumulation is on the rise as commercial space applications become more affordable and existing satellites near the end of their operational lifetimes. For geosynchronous equatorial orbits, solar radiation pressure provides a unique solution for the removal of larger debris such as inoperable satellites. Given the current state of the art in solar sailing technology, a CubeSat can be tasked to deorbit satellites on the order of 1000 kg using a high-performance solar sail for propulsion. This CubeSat, called “TugSat,” is simulated in this study, virtually deorbiting a satellite from geostationary orbit without the use of standard propulsion systems. This same TugSat can be reused indefinitely, between the geosynchronous equatorial orbit belt and the retirement orbit, to continuously remove debris from valuable geostationary orbit slots. The entire deorbit maneuver will demonstrate control of a satellite’s semimajor axis, eccentricity, inclination, and geosynchronous equatorial orbit belt longitude: all using techniques to optimize time rates of change in the satellite’s orbital elements. The TugSat concept provides a low-cost reusable means for geosynchronous equatorial orbit belt cleanup or open-ended geosynchronous equatorial orbit belt mission applications.

Plutino (15810) 1994 JR1, an accidental quasi-satellite of Pluto

Abstract In the Solar system, quasi-satellites move in a 1:1 mean motion resonance going around their host body like a retrograde satellite but their mutual separation is well beyond the Hill radius and the trajectory is not closed as they orbit the Sun, not the host body. Although they share the semi-major axis and the mean longitude of their host body, their eccentricity and inclination may be very different. So far, minor bodies temporarily trapped in the quasi-satellite dynamical state have been identified around Venus, the Earth, the dwarf planet (1) Ceres, the large asteroid (4) Vesta, Jupiter and Saturn. Using computer simulations, Tiscareno & Malhotra have predicted the existence of a small but significant population of minor bodies moving in a 1:1 mean motion resonance with Pluto. Here we show using N-body calculations that the plutino (15810) 1994 JR1 is currently an accidental quasi-satellite of Pluto and it will remain as such for nearly 350 000 years. By accidental we mean that the quasi-satellite phase is triggered (or terminated) not by a direct gravitational influence in the form of a discrete close encounter, but as a result of a resonance. The relative mean longitude of the plutino (15810) 1994 JR1 circulates with a superimposed libration resulting from the oscillation of the orbital period induced by the 2:3 mean motion resonance with Neptune. These quasi-satellite episodes are recurrent with a periodicity of nearly 2 Myr. This makes the plutino (15810) 1994 JR1 the first minor body moving in a 1:1 mean motion resonance with Pluto and the first quasi-satellite found in the trans-Neptunian region. It also makes Pluto the second dwarf planet, besides Ceres, to host a quasi-satellite. Our finding confirms that the quasi-satellite resonant phase is not restricted to small bodies orbiting major planets but is possible for dwarf planets/asteroids too. Moreover, the plutino (15810) 1994 JR1 could be considered as a possible secondary target for NASA's Pluto—Kuiper Belt Mission New Horizons after the main Pluto flyby in 2015. This opens the possibility of studying at first hand and for the first time a minor body in the quasi-satellite dynamical state.

ALICE: The Ultraviolet Imaging Spectrograph Aboard the New Horizons Pluto–Kuiper Belt Mission

The ALICE instrument is a lightweight (4.4 kg), low-power (4.4 watt) imaging spectrograph aboard the New Horizons mission to the Pluto system and the Kuiper Belt. Its primary job is to determine the relative abundances of various species in Pluto’s atmosphere. ALICE will also be used to search for an atmosphere around Pluto’s moon, Charon, as well as the Kuiper Belt Objects (KBOs) that New Horizons is expected to fly by after Pluto-Charon, and it will make UV surface reflectivity measurements of all of these bodies, as well as of Pluto’s smaller moons Nix and Hydra. The instrument incorporates an off-axis telescope feeding a Rowland-circle spectrograph with a 520–1870 A spectral passband, a spectral point spread function of 3–6 A FWHM, and an instantaneous spatial field-of-view that is 6 degrees long. Two different input apertures that feed the telescope allow for both airglow and solar occultation observations during the mission. The focal plane detector is an imaging microchannel plate (MCP) double delay-line detector with dual solar-blind opaque photocathodes (KBr and CsI) and a focal surface that matches the instrument’s 15-cm diameter Rowland-circle. In this paper, we describe the instrument in greater detail, including descriptions of its ground calibration and initial in flight performance. New Horizons launched on 19 January 2006.

Stern But Kind at NASA

NASA Administrator Michael Griffin has found a new chief for the agency's beleaguered earth and space sciences program, insiders say. Griffin has been introducing S. Alan Stern, executive director of the Southwest Research Institute in Boulder, Colorado, around NASA's Washington, D.C., headquarters as a successor to Mary Cleave, who announced last September that she would leave this spring. Stern, a planetary scientist, is the principal investigator on NASA's Pluto-Kuiper belt mission and an advocate for lunar exploration—music, no doubt, to Griffin's ears. His challenge will be to preserve the agency's $5.5 billion commitment to science projects in the face of a flat budget and the growing appetite of NASA's human flight program. Stern did not return messages, and a NASA spokesperson declined comment.

New Horizons Pluto–Kuiper Belt mission: design and simulation of the Pluto–Charon encounter

The primary goal of the New Horizons Pluto–Kuiper Belt mission is to explore Pluto by 2020, before Pluto's atmosphere collapses as predicted by scientists, and then explore the Kuiper Belt objects in an extended mission. The baseline mission plans to launch in January 2006, using a Jupiter gravity assist trajectory to reach Pluto. The New Horizons spacecraft will arrive at Pluto as early as 2015, depending on the launch vehicle. For such a mission, whose exploration takes place during a brief flyby period after a long cruise, a thorough planning of the encounter is especially critical to the realization of optimal science observations. A detailed Pluto encounter trajectory design that achieves both solar occultation and Earth occultation by both Pluto and Charon is described in this paper, along with discussions of the design rationale and considerations. Science observations and measurements planned for the Pluto–Charon encounter are simulated and analyzed, and a comprehensive Pluto–Charon encounter process filled with detailed science observation simulations is demonstrated in a 3-D animation.

No major increase for NASA under Bush budget plan

The Bush Administration's proposed 15.1‐ billion budget for NASA for fiscal year 2003 represents an increase of just .7% ($98 million) above the current 2002 budget level. While the budget proposal reflects an effort by the administration to encourage improvements in the agency's financial management and other performance metrics, scientists have questioned how changes in the budget would affect several programs.These changes include NASA's proposal to halt funding for the New Horizons Pluto‐Kuiper Belt Mission (see Eos, 5 March 2002) and a temporary moratorium on significant new Earth science mission starts.

Hannes: A mission to the asteroid belt

An asteroid belt mission is being studied by Swedish space authorities in cooperation with Russian, European, and American partners. The mission will perform a survey of the inner solar system with an emphasis on cosmogonic issues, i.e. it will study the importance of plasma processes in the formation and evolution of the solar system. For this purpose the asteroid belt will be visited several times to enable close studies of these primordial bodies, and their interaction with the solar wind. Cosmogony issues to be studied include detailed measurements of the solar wind aberration and its relation to plasma angular momentum transfer, electric current structures in interplanetary space and near small bodies, surface properties of asteroids, and interaction between the heliosphere and interstellar neutrals. Selection of asteroids to be visited will be done so that a variety of taxonomic types, shapes and sizes can be studied. A comet flyby during the mission may also be performed. The mission will carry charged particle and field instruments, a neutral particle imager, a dust/micrometeroid detector, and planetology instrumentation (including infrared and visible imagers) to fully investigate these processes which may shed light on the question of how the solar system has evolved. The mission calls for a small autonomous spacecraft with high reliability and an advanced payload. The platform concept studied has a dry mass of 150 kg, and a payload mass of 44 kg. Hannes is being studied with a planned launch in mid 2002 with Venus and Earth gravity assist maneuvers before the first asteroid encounter in early 2004. The mission is named after the late Nobel laureate Hannes Alfvén.