Altitude Polar Orbit Research Articles

Viability of an Electrically Driven Pump-Fed Hybrid Rocket for Small Launcher Upper Stages

An electrically driven pump-fed cycle for a hybrid rocket engine is proposed and compared to a simpler gas-pressurized feed system. A liquid-oxygen/paraffin-based fuel hybrid rocket engine which powers the third stage of a Vega-like launcher is considered. Third-stage ignition conditions are assigned, and engine design and payload mass are defined by a proper set of parameters. Uncertainties in the classical regression rate correlation coefficients are taken into account and robust design optimization is carried out with an approach based on an epsilon-constrained evolutionary algorithm. A mission-specific objective function, which takes into account both the payload mass and the ability of the rocket to reach the required final orbit despite uncertainties, is determined by an indirect trajectory optimization approach. The target orbit is a 700 km altitude polar orbit. Results show that electrically driven pump-fed cycle is a viable option for the replacement of the conventional gas-pressurized feed system. Robustness in the design is granted and a remarkable payload gain is achieved, using both present and advanced technologies for electrical systems.

Data Collection for Disaster Response from the International Space Station

Abstract. Remotely sensed data acquired by orbital sensor systems has emerged as a vital tool to identify the extent of damage resulting from a natural disaster, as well as providing near-real time mapping support to response efforts on the ground and humanitarian aid efforts. The International Space Station (ISS) is a unique terrestrial remote sensing platform for acquiring disaster response imagery. Unlike automated remote-sensing platforms it has a human crew; is equipped with both internal and externally-mounted remote sensing instruments; and has an inclined, low-Earth orbit that provides variable views and lighting (day and night) over 90 percent of the inhabited surface of the Earth. As such, it provides a useful complement to autonomous sensor systems in higher altitude polar orbits. NASA remote sensing assets on the station began collecting International Charter, Space and Major Disasters, also known informally as the International Disaster Charter (IDC) response data in May 2012. Since the start of IDC response in 2012, and as of late March 2015, there have been 123 IDC activations; NASA sensor systems have collected data for thirty-four of these events. Of the successful data collections, eight involved two or more ISS sensor systems responding to the same event. Data has also been collected by International Partners in response to natural disasters, most notably JAXA and Roscosmos/Energia through the Urugan program.

In-flight Performance and Initial Results of Plasma Energy Angle and Composition Experiment (PACE) on SELENE (Kaguya)

MAP-PACE (MAgnetic field and Plasma experiment—Plasma energy Angle and Composition Experiment) on SELENE (Kaguya) has completed its ∼1.5-year observation of low-energy charged particles around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measured the distribution function of low-energy electrons in the energy range 6 eV–9 keV and 9 eV–16 keV, respectively. IMA and IEA measured the distribution function of low-energy ions in the energy ranges 7 eV/q–28 keV/q and 7 eV/q–29 keV/q. All the sensors performed quite well as expected from the laboratory experiment carried out before launch. Since each sensor has a hemispherical field of view, two electron sensors and two ion sensors installed on the spacecraft panels opposite each other could cover the full 3-dimensional phase space of low-energy electrons and ions. One of the ion sensors IMA is an energy mass spectrometer. IMA measured mass-specific ion energy spectra that have never before been obtained at a 100 km altitude polar orbit around the Moon. The newly observed data show characteristic ion populations around the Moon. Besides the solar wind, MAP-PACE-IMA found four clearly distinguishable ion populations on the dayside of the Moon: (1) Solar wind protons backscattered at the lunar surface, (2) Solar wind protons reflected by magnetic anomalies on the lunar surface, (3) Reflected/backscattered protons picked-up by the solar wind, and (4) Ions originating from the lunar surface/lunar exosphere.

Three years of Atmospheric Infrared Sounder radiometric calibration validation using sea surface temperatures

This paper evaluates the absolute accuracy and stability of the radiometric calibration of the Atmospheric Infrared Sounder (AIRS) by analyzing the difference between the brightness temperatures measured at 2616 cm−1 and those calculated at the top of the atmosphere (TOA), using the Real‐Time Global Sea Surface Temperature (RTGSST) for cloud‐free night tropical oceans between ±30° latitude. The TOA correction is based on radiative transfer. The analysis of the first 3 years of AIRS radiances verifies the absolute calibration at 2616 cm−1 to better than 200 mK, with better than 16 mK/yr stability. The AIRS radiometric calibration uses an internal full aperture wedge blackbody with the National Institute of Standards and Technology (NIST) traceable prelaunch calibration coefficients. The calibration coefficients have been unchanged since launch. The analysis uses very tight cloud filtering, which selects about 7000 cloud‐free tropical ocean spectra per day, about 0.5% of the data. The absolute accuracy and stability of the radiometry demonstrated at 2616 cm−1 are direct consequences of the implementation of AIRS as a thermally controlled, cooled grating‐array spectrometer and meticulous attention to details. Comparable radiometric performance is inferred from the AIRS design for all 2378 channels. AIRS performance sets the benchmark for what can be achieved with a state‐of‐the‐art hyperspectral radiometer from polar orbit and what is expected from future hyperspectral sounders. AIRS was launched into a 705 km altitude polar orbit on NASA's Earth Observation System (EOS) Aqua spacecraft on 4 May 2002. AIRS covers the 3.7–15.4 micron region of the thermal infrared spectrum with a spectral resolution of ν/Δν = 1200 and has returned 3.7 million spectra of the upwelling radiance each day since the start of routine data gathering in September 2002.

Single-event performance of COTS-based MPU under flare and non-flare conditions

We investigated the in-orbit performance of a high-performance on-board computer developed with commercial off-the-shelf (COTS) technology in terms of its performance during the occurrence of single event effects. The processor worked and performed successfully both under normal and under solar flare conditions in 800 km altitude polar orbit. During a solar flare, the occurrence of single events increased by a factor of more than four compared with normal conditions. The area where single events occurred during the solar flare spread to the polar region, whereas normally they are limited to the region of South-Atlantic anomalies (SAA). Our results suggest that the performance of our COTS processor is sufficient for future space applications.

Development of the Gravity Probe B flight mission

Gravity Probe B is an experiment to measure the geodetic and frame-dragging precessions, relative to the “fixed” “stars”, of a gyroscope placed in a 650 km altitude polar orbit about the earth. For Einstein's general relativity, the precessions are calculated to be 6.6 arcsec/yr for the geodetic precession and 0.042 arcsec/yr for the frame-dragging precession. The goal of the experiment is to measure these precessions to better than 0.01% and 1%, respectively. This paper gives an overview of the experiment and a discussion of the flight hardware development and its status. This paper also includes an estimate of the geodetic and frame-dragging errors expected for the experiment.

The small satellite NINA-MITA to study galactic and solar cosmic rays in low-altitude polar orbit

The satellite MITA, carrying on board the scientific payload NINA-2, was launched on July the 15 th , 2000 from the cosmodrome of Plesetsk (Russia) with a Cosmos-3M rocket. The satellite and the payload are currently operating within nominal parameters. NINA-2 is the first scientific payload for the technological flight of the Italian small satellite MITA. The detector used in this mission is identical to the one already flying on the Russian satellite Resurs-O1 n.4 in a 840-km sun-synchronous orbit, but makes use of the extensive computer and telemetry capabilities of MITA bus to improve the active data acquisition time. NINA physics objectives are to study cosmic nuclei from hydrogen to iron in the energy range between 10 MeV/n and 1 GeV/n during the years 2000–2003, that is the solar maximum period. The device is capable of charge identification up to iron with isotope sensitivity up to oxigen. The 87.3 degrees, 460 km altitude polar orbit allows investigations of cosmic rays of solar and galactic origin, so to study long and short term solar transient phenomena, and the study of the trapped radiation at higher geomagnetic cutoff.

The selene project and the following lunar mission

The SELENE (SELenological and Engineering Explorer) project is the NASDA's first joint lunar mission with ISAS which is planned to be launched in 2003 by Japanese H-IIA launch vehicle. The major objectives of the SELENE project are researches of lunar science and feasibility of lunar utilization by the global mapping from a low lunar orbit, as well as the development of key technologies for the lunar exploration such as the soft landing technology. SELENE consists of 2 satellites, a main polar orbiter with a propulsion/landing module and a small relay satellite. The main orbiter will be inserted into 100 km altitude polar circular orbit for its 1-year mapping mission. About a dozen of scientific instruments on the main orbiter are used for the extensive global mapping of lunar surface and lunar-terrestrial science. Far-side gravimetry is implemented by the relay satellite to measure 4 way range rate from the ground station to the main orbiter. After its 1-year observation from the low lunar orbit, the propulsion/landing module will be separated to implement the soft landing experiment to verify its technology. After its successful landing on the nearside of the moon, lunar gravimetry and selenodecy in high resolution will be implemented by means of differential VLBI method with a radio source instrument on the propulsion/landing module and the relay satellite. Now, the next Lunar mission, called SELENE-2nd is being studied in the same framework of ISAS/NASDA joint program. SELENE-2nd will perform lunar science on the surface of the Moon, which will provide the more detailed data to solve the origin and evolution of the Moon in conjunction with the data obtained by SELENE. SELENE-2nd will also give the opportunity for the development of key technologies such as survival technology and traverse technology necessary for the future activities on the Moon. This paper describes the current status of SELENE including the result of phase-B study, and introduce one of the options of SELENE-2nd concept.

Exploring the Limits of GPS-Based Precise Orbit Determination

High-fidelity numerical simulations were conducted to assess the anticipated level of radial orbit error for low-altitude geodetic and oceanographic satellites tracked by GPS. Tracking data were simulated for a GPS flight receiver in 700 and 300 km altitude polar orbits and for a ground network of 24 GPS tracking stations. The simulations suggest that it should be possible to achieve 3 cm radial orbit accuracy for altitudes in the 700 km range, either with tuning of the geopotential or with filtering techniques that exploit the continuous, three-dimensional nature of GPS tracking. The simulations also suggest it should be possible to achieve 6 cm radial orbit accuracy for altitudes in the 300 km range. To improve upon this level of accuracy at such low altitudes, improvement of the geopotential and atmospheric drag models will probably be required.

Energetic neutral atom imaging by the Astrid microsatellite

The microsatellite Astrid carried the first instrument (PIPPI, Prelude in Planetary Particle Imaging) specifically designed to perform energetic neutral atom (ENA) imaging. It made measurements from a low altitude (1000 km) polar orbit in the energy range ∼13–140 keV. The ENA images, obtained from near-pole vantage points, adequately reflect general morphological features of the ring current such as a global dawn — dusk asymmetry. The detected ENA peak fluxes (500 – 2000 cm −2s −1sr −1keV −1 for 26 – 37 keV) and structure of the ENA images correlate well with magnetospheric activity throughout the entire data set. The Astrid results demonstrate a considerable potential for ENA imaging from low altitude polar orbits. High ENA fluxes, large angular size of the generation region and simultaneous sampling over all local times are major advantages of such imaging.

Energetic particle environment in near — Earth orbit

The hazard of exposure to high doses of ionizing radiation is one of the primary concerns of extended manned space missions and a continuous threat for the numerous spacecraft in operation today. In the near - Earth environment the main sources of radiation are solar energetic particles (SEP), galactic cosmic rays (GCR), and geomagnetically trapped particles, predominantly protons and electrons. The intensity of the SEP and GCR source depends primarily on the phase of the solar cycle. Due to the shielding effect of the Earth's magnetic field, the observed intensity of SEP and GCR particles in a near-Earth orbit will also depend on the orbital parameters altitude and inclination. The magnetospheric source strength depends also on these orbital parameters because they determine the frequency and location of radiation belt passes. In this paper an overview of the various sources of radiation in the near - Earth orbit will be given and first results obtained with the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) will be discussed. SAMPEX was launched on 3 July 1992 into a near polar (inclination 82°) low altitude (510 × 675 km) orbit. The SAMPEX payload contains four separate instruments of high sensitivity covering the energy range 0.5 to several hundred MeV/nucleon for ions and 0.4 to 30 MeV for electrons. This low altitude polar orbit with zenith-oriented instrumentation provides a new opportunity for a systematic study of the near - Earth energetic particle environment.

Proton flare and magnetic storm effect in the vicinity of the earth

We have developed a model and associated computational procedure for estimating energetic proton exposures during a major solar proton event that occur in combination with a large magnetic storm. Transmission functions for solar protons are computed using geomagnetic vertical cutoff data for quiescent and disturbed conditions. Predicted exposures in low altitude polar orbit are found to be orders of magnitude greater for severe magnetic storm conditions than are corresponding exposures in the absence of major disturbances. We examine the response scenario for the events of November 1960 as an example.

Observation and prediction of SEU in Hitachi SRAMs in low altitude polar orbits

In-orbit SEU (single event upset) data from three microsatellites are separated into galactic cosmic ray (GCR), South Atlantic anomaly (SAA) and solar flare upsets. Heavy ion and proton testing of the same devices is reported, and predictions using LET (linear energy transfer)-dependent ion cross sections and a two-parameter fit to proton cross section data are compared with in-flight data. SEU trends in memory devices from a single manufacturer, from 16 kb to 4 Mb, are identified. The increasing density of the memories is found to be accompanied by an apparent decreasing sensitivity to the heavy ion environment in polar orbit. Although the LET threshold decreases, the decrease in asymptotic cross section has a greater effect. However, the sensitivity to proton-induced upsets is nearly similar in all memories, so the proton effects become dominant by an order of magnitude. This has important implications for future spacecraft with large onboard memories and high performance processors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An evolutionary role for small comsats

A review of orbit and constellation options is presented for regional and global coverage in real time for voice-based communication and for intermittent or delayed messaging. An evolutionary trend to increasing spacecraft size and cost is explained in terms of increasing productivity. A viewpoint is presented that small satellites do not have unique technical capabilities but do promise lower unit costs to build and launch. These features coupled with orbit and constellation characteristics make smallsats attractive in start up, low capacity and experimental missions and particularly in global systems requiring many satellites. Comments are made on the system features of some of the current mobile system filings before the FCC which rely on small satellites for communications and position location. Two additional applications of small satellites are presented, one for a medium capacity GEO satellite for domestic or regional fixed satellite service at C or Ku-band. The other is for a constellation of 3 medium altitude polar orbit satellites to provide high latitude mobile service as a complement to a global geosynchronous-based system for aeronautical, maritime and land mobile communications.

Proton induced upsets in the low altitude polar orbit

The authors report on observations of single-event upsets occurring in large dynamic NMOS and static CMOS memories onboard the low-altitude, polar orbiting UOSAT-2 satellite. The strong localization of these upsets to the South Atlantic region leads to the conclusion that the majority of upsets in these devices are caused by nuclear reactions involving energetic radiation-belt protons encountered in the South Atlantic anomaly. The dynamic RAM upset rates are in agreement with the predictions of W.L. Bendel and E.L. Peterson (1983). Static CMOS RAMs are also found to be sensitive to proton-induced upsets, but presently there are not enough ground test data to make predictions. >

The SEU Risk Assessment of Z80A, 8086 and 80C86 Microprocessors Intended for Use in a Low Altitude Polar Orbit

This paper presents the results of a test and analysis program carried out in support of an Earth Resources Satellite project in order to provide a quantitative SEU risk assessment for certain microprocessor based subsystems. The key features of the program were the low cost and comparative simplicity of the test techniques which, nevertheless, provided sufficient data for a quantitative risk assessment using the CREME suite of programs.

Time Dissemination Capabilities via Navigation Satellites

There are currently two navigation satellite systems employing clock-carrying satellites that are useable for the dissemination of Precise Time and Time Interval (PTTI). These are the Navy Navigation Satellite System (NNSS or Transit), which now has five satellites in low altitude (1000 km) polar orbits, and the Global Positioning System (GPS), which currently has six satellites in circular (20,000 km) twelve-hour orbits. The US Naval Observatory (USNO) is engaged in an ongoing program to improve the performance of these systems and to make them operational time dissemination systems as soon as possible.Transit has a demonstrated time-transfer capability in the 25 microsecond region. GPS is capable of time transfers of better than 100 nanoseconds. This paper describes equipment available for recovering time from the satellites, current efforts aimed at improving both satellite system and receiver performance, and the data collection and reporting schemes used at the USNO to provide data for publication. F...

High resolution measurements of space radiation effects on silicon surface-barrier detectors

Two high-resolution charged particle spectrometers employing silicon surface-barrier detectors have been operated in an 800 km altitude polar orbit for a 26-month period between October 1971 and December 1973-Based on existing trapped radiation models and the measured solar flare environment during this period the detectors were exposed to a proton fluence of 2.8 t 1013 protons/cm2 at energies > 400 keV and an electron fluence of 4.5 t 1013 electrons/cm2 at energies > 50 keV. High-resolution pulse height spectra of the alpha particles from low-intensity Americium-241 in-flight calibration sources show that the resolutions of the detectors did not degrade more than 5 percent and that the gains of the system did not vary more than 1.2 percent as a result of this exposure. Two aspects of detector operation are considered responsible for this performance. First, the incident detectors were operated with the rear, aluminum contact exposed to the radiation environment instead of the front, gold contact. The more intense lower energy radiation is therefore stopped in the rear ohmic contact region instead of in the front surface-barrier junction region and the overall damage effects are significantly reduced. Second, a detector bias technique was employed that automatically maintained a constant depletion potential across the detector independent of variations in leakage current due to radiation damage.