Curiosity’s Mars Hand Lens Imager (MAHLI) Investigation

The Mars Science Laboratory (MSL) Mars Hand Lens Imager (MAHLI) investigation will use a 2-megapixel color camera with a focusable macro lens aboard the rover, Curiosity, to investigate the stratigraphy and grain-scale texture, structure, mineralogy, and morphology of geologic materials in northwestern Gale crater. Of particular interest is the stratigraphic record of a ～5?km thick layered rock sequence exposed on the slopes of Aeolis Mons (also known as Mount Sharp). The instrument consists of three parts, a?camera head mounted on the turret at the end of a robotic arm, an electronics and data storage assembly located inside the rover body, and a calibration target mounted on the robotic arm shoulder azimuth actuator housing. MAHLI can acquire in-focus images at working distances from ～2.1?cm to infinity. At the minimum working distance, image pixel scale is ～14?μm per pixel and very coarse silt grains can be resolved. At the working distance of the Mars Exploration Rover Microscopic Imager cameras aboard Spirit and Opportunity, MAHLI’s resolution is comparable at ～30?μm per pixel. Onboard capabilities include autofocus, auto-exposure, sub-framing, video imaging, Bayer pattern color interpolation, lossy and lossless compression, focus merging of up to 8 focus stack images, white light and longwave ultraviolet (365 nm) illumination of nearby subjects, and 8 gigabytes of non-volatile memory data storage.     

The Cassini Ion and Neutral Mass Spectrometer (INMS) Investigation

The Cassini Ion and Neutral Mass Spectrometer (INMS) investigation will determine the mass composition and number densities of neutral species and low-energy ions in key regions of the Saturn system. The primary focus of the INMS investigation is on the composition and structure of Titan’s upper atmosphere and its interaction with Saturn’s magnetospheric plasma. Of particular interest is the high-altitude region, between 900 and 1000 km, where the methane and nitrogen photochemistry is initiated that leads to the creation of complex hydrocarbons and nitriles that may eventually precipitate onto the moon’s surface to form hydrocarbon–nitrile lakes or oceans. The investigation is also focused on the neutral and plasma environments of Saturn’s ring system and icy moons and on the identification of positive ions and neutral species in Saturn’s inner magnetosphere. Measurement of material sputtered from the satellites and the rings by magnetospheric charged particle and micrometeorite bombardment is expected to provide information about the formation of the giant neutral cloud of water molecules and water products that surrounds Saturn out to a distance of ∼12 planetary radii and about the genesis and evolution of the rings.The INMS instrument consists of a closed ion source and an open ion source, various focusing lenses, an electrostatic quadrupole switching lens, a radio frequency quadrupole mass analyzer, two secondary electron multiplier detectors, and the associated supporting electronics and power supply systems. The INMS will be operated in three different modes: a closed source neutral mode, for the measurement of non-reactive neutrals such as N₂ and CH₄; an open source neutral mode, for reactive neutrals such as atomic nitrogen; and an open source ion mode, for positive ions with energies less than 100 eV. Instrument sensitivity is greatest in the first mode, because the ram pressure of the inflowing gas can be used to enhance the density of the sampled non-reactive neutrals in the closed source antechamber. In this mode, neutral species with concentrations on the order of ≥10⁴ cm⁻³ will be detected (compared with ≥10⁵ cm⁻³ in the open source neutral mode). For ions the detection threshold is on the order of 10⁻² cm⁻³ at Titan relative velocity (6 km sec⁻¹). The INMS instrument has a mass range of 1–99 Daltons and a mass resolutionM/ΔM of 100 at 10% of the mass peak height, which will allow detection of heavier hydrocarbon species and of possible cyclic hydrocarbons such as C₆H₆.The INMS instrument was built by a team of engineers and scientists working at NASA’s Goddard Space Flight Center (Planetary Atmospheres Laboratory) and the University of Michigan (Space Physics Research Laboratory). INMS development and fabrication were directed by Dr. Hasso B. Niemann (Goddard Space Flight Center). The instrument is operated by a Science Team, which is also responsible for data analysis and distribution. The INMS Science Team is led by Dr. J. Hunter Waite, Jr. (University of Michigan).This revised version was published online in July 2005 with a corrected cover date.     

Direct observation of processes in a solidifying dispersion

The evolution of a dispersion under the action of temperature gradients and solidification was followed optically in a transparent molten salt (CsCl) with inclusions of Pb-droplets and gas bubbles. This system is believed to model a solidifying metallic alloy. Rejection of Pb-particles by the solidification front was observed, while large gas bubbles were incorporated. Thermocapillary convection at the gas bubbles considerably distorted the temperature field and even caused local remelting. Marangoni migration of bubbles was not observed, contrary to expectations.     

Analysis of the orbit lifetime of CubeSats in low Earth orbits including periodic variation in drag due to attitude motion

It is estimated that more than 22,300 human-made objects are in orbit around the Earth, with a total mass above 8,400,000 kg. Around 89% of these objects are non-operational and without control, which makes them to be considered orbital debris. These numbers consider only objects with dimensions larger than 10 cm. Besides those numbers, there are also about 2000 operational satellites in orbit nowadays. The space debris represents a hazard to operational satellites and to the space operations. A major concern is that this number is growing, due to new launches and particles generated by collisions. Another important point is that the development of CubeSats has increased exponentially in the last years, increasing the number of objects in space, mainly in the Low Earth Orbits (LEO). Due to the short operational time, CubeSats boost the debris population. One of the requirements for space debris mitigation in LEO is the limitation of the orbital lifetime of the satellites, which needs to be lower than 25 years. However, there are space debris with longer estimated decay time. In LEÓs, the influence of the atmospheric drag is the main orbital perturbation, and is used in maneuvers to increment the losses in the satellite orbital energy, to locate satellites in constellations and to accelerate the decay.The goal of the present research is to study the influence of aerodynamic rotational maneuver in the CubeSat?s orbital lifetime. The rotational axis is orthogonal to the orbital plane of the CubeSat, which generates variations in the ballistic coefficient along the trajectory. The maneuver is proposed to accelerate the decay and to mitigate orbital debris generated by non-operational CubeSats. The panel method is selected to determine the drag coefficient as a function of the flow incident angle and the spinning rate. The pressure distribution is integrated from the satellite faces at hypersonic rarefied flow to calculate the drag coefficient. The mathematical model considers the gravitational potential of the Earth and the deceleration due to drag. To analyze the effects of the rotation during the decay, multiple trajectories were propagated, comparing the results obtained assuming a constant drag coefficient with trajectories where the drag coefficient changes periodically. The initial perigees selected were lower than 400 km of altitude with eccentricities ranging from 0.00 to 0.02. Six values for the angular velocity were applied in the maneuver. The technique of rotating the spacecraft is an interesting solution to increase the orbit decay of a CubeSat without implementing additional de-orbit devices. Significant changes in the decay time are presented due to the increase of the mean drag coefficient calculated by the panel method, when the maneuver is applied, reducing the orbital lifetime, however the results are independent of the angular velocity of the satellite.     

Observational evidence for the binary model of X-ray bursters

Most, but not all, theoretical models of X-ray bursters require a binary system consisting of a mass donating star and a neutron star. The observational evidence in support of this model, however, is both indirect and meager. We have detected absorption dips in the X-ray spectrum of the Burster MXB 1916-05 with the IPC and the MPC on the Einstein Observatory which occur with a binary period of 2985 seconds. These dips are shown to be the result of a gas stream emanating from a companion star and hence this data represents the first direct evidence of the binary nature of X-ray bursters. Detailed models of the interaction of the gas stream with the accretion disk are presented. A 22nd mag. optical candidate for the system has been found.     

Improving international space cooperation: Considerations for the USA

In 2000 there were 40 different countries that had registered space agencies. By 2009 that number had continued to grow to 55. This article discusses how cooperation allows a nation to leverage resource and reduce risk; improve global engagement; and enhance diplomatic prestige of engaged states, political sustainability and workforce stability. The obstacles and impediments to cooperation are substantial, and are manifested through various anti-collaborative behaviors. To achieve success, these obstacles and impediments must be understood and confronted. The article examines the substantial challenges posed by technology transfer constraints, international and domestic politics, and exceptionalism perspectives. Given the imperative to cooperate, four frameworks (cooperation, augmentation, interdependence, and integration) can be employed to overcome these challenges and achieve success.     

The Ultraviolet Spectrograph on NASA’s Juno Mission

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS.     

Review of German work on controlled re-entry technology

The concept of a reusable space transporter formed a focus of much effort for the German firms Junkers Flugzeug- und Motorenwerke (JFM), Messerschmitt-Bölkow-Blohm und Voss (MBB) and Entwicklungsring Nord (ERNO), together with the Deutsche Forschungs- und Veruchsanstalt für Luft- und Raumfahrt (DFVLR) and different University institutes during the decade beginning 1962. The result was the definition, in 1972, of a program of the “Arbeitsgruppe Rückkehrtechnologie” (ART, Working group for reentry technology) which integrated all relevant capacities of research establishments, industry, and universities. The aim was the maintenance of the technical-scientific capabilities for advanced high velocity flight systems and to qualify for international cooperation in this field. Only a small part of this work could be completed, as the ART-program was never accepted by the German Ministry for Research and Technology. So the current work was stopped by the end of 1975. Nevertheless, as the ART-program can serve as a guide-line for possible future work a summary of this work is given.     

Enhancing Europe's capabilities in space research and technology: Towards a European Space Board

With the proposed implementation of a European space policy and the prospect of several major undertakings in the space domain the European Union should decide to set up a high-level independent body and confer on it the authority and means to provide expert advice on space-related subjects to its institutions, policy makers and agencies, as well as to the space research community. Although the political and legislative situation in the USA is different from that in Europe, such a body has existed there since 1959 and has proven most useful. The current situation in Europe is analysed and the arguments for setting up such a structure are presented. It is suggested that the foundations for this new advisory structure can be found in the existing European Space Science Committee, the European Science Foundation's expert committee on space research. A structure and remit is proposed for such a body and elements of its mode and means of operations are discussed.