Space-based Earth remote sensing: Part 1. Satellite orbit theory

Author(s):  
Sung Wook Paek 1 ◽  
Sangtae Kim 2

The development of oceanography and meteorology has greatly benefited from remotely sensed satellite data of the atmosphere and ocean. For oceanographers, meteorologists, hydrologists and climatologists to obtain high-quality satellite data, orbits along which the satellites move must be designed carefully. For this reason, Sun-synchronous, repeat ground track orbits have traditionally been used for visible-wavelength and infrared Earth observations. As the needs for varied datasets are growing, however, new classes of Earth-observing missions are emerging such as interferometry and radiometry to name a few. On the other side, satellite platforms and onboard sensors are getting more compact and less expensive, allowing developing nations to launch their own satellites and under-researched parts of the Earth be studied. In light of these changes, this paper introduces new types of satellite orbits from celestial mechanics perspectives, whose applications will be detailed further in the follow-up work.

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
I. Kutiev ◽  
S. Stankov

Recent progress in using the satellite data for various PRIME purposes is briefly presented. The satellite data base is already in operation and contains data of local plasma and neutral atmosphere parameters taken from several ionospheric satellites. A method of tracing the locally measured parameters along the magnetic field lines down to hmF2 is developed using a theoretical F-region code. This method is applied to receive f0F2sat needed to test monthly median and instantaneous mapping methods. In order to reduce the uncertainties arising from the unknown photoionization and recombination rates, f0F2 is calibrated at one point on the satellite orbit with a Vertical Incident (VI) f0F2 and their ratio is then assumed constant along the whole satellite track over the PRIME area. The testing procedure for monthly median maps traces the measured plasma density down to a basic height of 400 km, where individual f0F2sat values are accumulated in every time/subarea bin within the given month, then their median is calibrated with the available medians from the VI ionosonde network. From all available satellite orbits over the PRIME area, 35 of them were found to pass over two VI ionosonde stations. The second station in these orbits was used to check the calculated f0F2sat with the measured VI f0F2. The standard deviation was found to be only 0.15 MHz.


The accurate determination of satellite orbits depends on an adequate accumulation of observations, a sound dynamical theory and a fairly sophisticated sequence of numerical computations. The particular patterns of observation, theory and computation are considered in relation to the objectives of orbit determination. Factors to be taken into account are the type, accuracy and spread of observations; perturbations of the orbit due to air drag, attraction of the Earth, Moon, and Sun, and solar radiation pressure; and the speed and cost of available computers. These factors, together with the overall objectives, determine the main features of the computation; whether to use special or general perturbation techniques, what length of orbit arc to use, what parameters to determine and how to present the results.


2019 ◽  
Vol 75 ◽  
pp. 01006
Author(s):  
Evgenii A. Maltsev ◽  
Yuri A. Maglinets ◽  
Gennady M. Tsibulskii

This work describes the technology to identify firebreak plowing objects of agriculture fields based on the satellite data of the Earth Remote Sensing within the medium and high spatial resolution. The technology uses a model of the firebreak plowing object, vegetation indexes and spatial relations between objects.


2007 ◽  
Vol 13 (2) ◽  
pp. 39-42
Author(s):  
A.I. Kirillov ◽  
◽  
Ye.I. Kapustin ◽  
N.A. Kirillova ◽  
E.I. Makhonin ◽  
...  

2021 ◽  
Vol 13 (11) ◽  
pp. 2201
Author(s):  
Hanlin Ye ◽  
Huadong Guo ◽  
Guang Liu ◽  
Jinsong Ping ◽  
Lu Zhang ◽  
...  

Moon-based Earth observations have attracted significant attention across many large-scale phenomena. As the only natural satellite of the Earth, and having a stable lunar surface as well as a particular orbit, Moon-based Earth observations allow the Earth to be viewed as a single point. Furthermore, in contrast with artificial satellites, the varied inclination of Moon-based observations can improve angular samplings of specific locations on Earth. However, the potential for estimating the global outgoing longwave radiation (OLR) from the Earth with such a platform has not yet been fully explored. To evaluate the possibility of calculating OLR using specific Earth observation geometry, we constructed a model to estimate Moon-based OLR measurements and investigated the potential of a Moon-based platform to acquire the necessary data to estimate global mean OLR. The primary method of our study is the discretization of the observational scope into various elements and the consequent integration of the OLR of all elements. Our results indicate that a Moon-based platform is suitable for global sampling related to the calculation of global mean OLR. By separating the geometric and anisotropic factors from the measurement calculations, we ensured that measured values include the effects of the Moon-based Earth observation geometry and the anisotropy of the scenes in the observational scope. Although our results indicate that higher measured values can be achieved if the platform is located near the center of the lunar disk, a maximum difference between locations of approximately 9 × 10−4 W m−2 indicates that the effect of location is too small to remarkably improve observation performance of the platform. In conclusion, our analysis demonstrates that a Moon-based platform has the potential to provide continuous, adequate, and long-term data for estimating global mean OLR.


Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Maddalena Mochi ◽  
Giacomo Tommei

The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Belt. However, some asteroids can run on trajectories that come close to, or even intersect, the orbit of the Earth. These objects are known as Near Earth Asteroids (NEAs) or Near Earth Objects (NEOs) and may entail a risk of collision with our planet. Predicting the occurrence of such collisions as early as possible is the task of Impact Monitoring (IM). Dedicated algorithms are in charge of orbit determination and risk assessment for any detected NEO, but their efficiency is limited in cases in which the object has been observed for a short period of time, as is the case with newly discovered asteroids and, more worryingly, imminent impactors: objects due to hit the Earth, detected only a few days or hours in advance of impacts. This timespan might be too short to take any effective safety countermeasure. For this reason, a necessary improvement of current observation capabilities is underway through the construction of dedicated telescopes, e.g., the NEO Survey Telescope (NEOSTEL), also known as “Fly-Eye”. Thanks to these developments, the number of discovered NEOs and, consequently, imminent impactors detected per year, is expected to increase, thus requiring an improvement of the methods and algorithms used to handle such cases. In this paper we present two new tools, based on the Admissible Region (AR) concept, dedicated to the observers, aiming to facilitate the planning of follow-up observations of NEOs by rapidly assessing the possibility of them being imminent impactors and the remaining visibility time from any given station.


GPS Solutions ◽  
2021 ◽  
Vol 25 (4) ◽  
Author(s):  
Bingbing Duan ◽  
Urs Hugentobler

AbstractTo resolve undifferenced GNSS phase ambiguities, dedicated satellite products are needed, such as satellite orbits, clock offsets and biases. The International GNSS Service CNES/CLS analysis center provides satellite (HMW) Hatch-Melbourne-Wübbena bias and dedicated satellite clock products (including satellite phase bias), while the CODE analysis center provides satellite OSB (observable-specific-bias) and integer clock products. The CNES/CLS GPS satellite HMW bias products are determined by the Hatch-Melbourne-Wübbena (HMW) linear combination and aggregate both code (C1W, C2W) and phase (L1W, L2W) biases. By forming the HMW linear combination of CODE OSB corrections on the same signals, we compare CODE satellite HMW biases to those from CNES/CLS. The fractional part of GPS satellite HMW biases from both analysis centers are very close to each other, with a mean Root-Mean-Square (RMS) of differences of 0.01 wide-lane cycles. A direct comparison of satellite narrow-lane biases is not easily possible since satellite narrow-lane biases are correlated with satellite orbit and clock products, as well as with integer wide-lane ambiguities. Moreover, CNES/CLS provides no satellite narrow-lane biases but incorporates them into satellite clock offsets. Therefore, we compute differences of GPS satellite orbits, clock offsets, integer wide-lane ambiguities and narrow-lane biases (only for CODE products) between CODE and CNES/CLS products. The total difference of these terms for each satellite represents the difference of the narrow-lane bias by subtracting certain integer narrow-lane cycles. We call this total difference “narrow-lane” bias difference. We find that 3% of the narrow-lane biases from these two analysis centers during the experimental time period have differences larger than 0.05 narrow-lane cycles. In fact, this is mainly caused by one Block IIA satellite since satellite clock offsets of the IIA satellite cannot be well determined during eclipsing seasons. To show the application of both types of GPS products, we apply them for Sentinel-3 satellite orbit determination. The wide-lane fixing rates using both products are more than 98%, while the narrow-lane fixing rates are more than 95%. Ambiguity-fixed Sentinel-3 satellite orbits show clear improvement over float solutions. RMS of 6-h orbit overlaps improves by about a factor of two. Also, we observe similar improvements by comparing our Sentinel-3 orbit solutions to the external combined products. Standard deviation value of Satellite Laser Ranging residuals is reduced by more than 10% for Sentinel-3A and more than 15% for Sentinel-3B satellite by fixing ambiguities to integer values.


2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Rebecca Gormley ◽  
Brian Vickers ◽  
Brooke Cheng ◽  
Wendy V. Norman

Abstract Background Multiple options for permanent or long-acting contraception are available, each with adverse effects and benefits. People seeking to end their fertility, and their healthcare providers, need a comprehensive comparison of methods to support their decision-making. Permanent contraceptive methods should be compared with long-acting methods that have similar effectiveness and lower anticipated adverse effects, such as the levonorgestrel-releasing intrauterine contraception (LNG-IUC). We aimed to understand the comparability of options for people seeking to end their fertility, using high-quality studies. We sought studies comparing laparoscopic tubal ligation, hysteroscopic tubal occlusion, bilateral salpingectomy, and insertion of the LNG-IUC, for effectiveness, adverse events, tolerability, patient recovery, non-contraceptive benefits, and healthcare system costs among females in high resource countries seeking to permanently avoid conception. Methods We followed PRISMA guidelines, searched EMBASE, Pubmed (Medline), Web of Science, and screened retrieved articles to identify additional studies. We extracted data on population, interventions, outcomes, follow-up, health system costs, and study funding source. We used the Newcastle–Ottawa Scale to assess risk of bias and excluded studies with medium–high risk of bias (NOS < 7). Due to considerable heterogeneity, we performed a narrative synthesis. Results Our search identified 6,612 articles. RG, BV, BC independently reviewed titles and abstracts for relevance. We reviewed the full text of 154 studies, yielding 34 studies which met inclusion criteria. We excluded 10 studies with medium–high risk of bias, retaining 24 in our synthesis. Most studies compared hysteroscopic tubal occlusion and/or laparoscopic tubal ligation. Most comparisons reported on effectiveness and adverse events; fewer reported tolerability, patient recovery, non-contraceptive benefits, and/or healthcare system costs. No comparisons reported accessibility, eligibility, or follow-up required. We found inconclusive evidence comparing the effectiveness of hysteroscopic tubal occlusion to laparoscopic tubal ligation. All studies reported adverse events. All forms of tubal interruption reported a protective effect against cancers. Tolerability appeared greater among tubal ligation patients compared to hysteroscopic tubal occlusion patients. No high-quality studies included the LNG-IUC. Conclusions Studies are needed to directly compare surgical forms of permanent contraception, such as tubal ligation or removal, with alternative options, such as intrauterine contraception to support decision-making. Systematic review registration PROSPERO [CRD42016038254].


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