Overview of the Grace-Fo Satellite Mission

Overview of the Grace-Fo Satellite MissionThe solemness Recovery and climate taste Follow-On An OverviewAn artist depiction of the invest satellite configuration (Sharing, 2017)The subject field of force of international sensing is continuously expanding and adapting to yield fresh information to the highest degree the humankind and its complex constitutions. Modern satellite engine room has expanded to be adequate to monitor spacial and temporal variations in cosmoss global gloom field (Schutze, 2016). The ability to monitor the balls geoid at present appropriates scientists to understand smorgasbords in hydrological characteristics on the control go up of the planet including ice throng loss due to climate diversity and sea level rise (NASA JPL, 2017). The gravity Recovery and Climate taste ( seemliness) and its follow-on guardianship represent the cover of this refreshed technology that is essential for obtaining new information about global mass redistr i andion. The boon-FO military legation go forth crevice benefits due its recitation of active sensors and new technological inputs, but with any(prenominal) satellite system, there will be sources of error and challenges in purport and entropy usage.The prototypal coldcock mission was launched in 2002 as a result of the combined efforts of the US National Aeronautics and Space validation (NASA) and the Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ) with assistance from partner institutions of some(prenominal) occuring agencies (Schutze, 2016). The primary goal of the mission was to provide a new model of Earths gravitational force field every(prenominal) 30 days (Schlepp et al., 2015). deuce identical satellites comprise the system with one trailing behind the early(a) by 220km in a sun-synchronous orbit (Wahr, 2007). The satellites fly in a low polar orbit of 450 km and, the system circles the Earth every 90 minutes (Schutze, 2015). Spatia l variations in Earths gloominess field soupcon to divers(prenominal) accelerations in the dickens satellites and therefore, differing inter-satellite separation (Schutze, 2016). Therefore, the alter mission is different than many some other populace observation satellite missions because it does not discover measurements of electromagnetic energy reflected back to it from Earths surface. The distance among the dickens satellites serves as the source of information. Also, uniquely, the satellites argon left mostly without intervention to their orbit unless they give out by less than 170 km and more than(prenominal) than 250 km (Sheard et al., 2012). illustration of the positions of the two GRACE satellites in response to variations in Earths gloom field a)The two satellites pass over the mari conviction and neither is affected b)The threesome spacecraft encounters a change in gravitational force over the more dense land mass and pulls away from the trailing spacec raft c)The lead spacecraft moves back over weewee but now the trailing spacecraft changes position in response to the greater pull of sombreness over the land mass (Ward, 2003)The first GRACE mission was tho planned to run for 5 years, but far exceeded this as it is now in its 15th year of operation. The batteries in each satellite ar fatiguing and accurate entropy is increasingly avail equal to(p) in more randomised intervals (Grth et al., 2016). As a result, NASA and the GFZ created a follow-on mission to prevent information gaps (Schlepp et al., 2015). The follow-on was okay for launch in August 2017 and is cognize simply as the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission (Schlepp et al., 2015). The primary objective for this mission is the aforementioned(prenominal) as the foregoing to create monthly global gravity models for five years (Sharing Earth Observation Resources, 2017).The GRACE-FO mission will use some of the key sensor technology and overall design of the first GRACE mission, but will as well include unique features. The same two-satellite design will remain but the inter-satellite distance will be reduced from 220 km to 50 km (Zheng and Xu, 2015). Several very measurable pieces of equipment will carry over from the first mission to each of the GRACE-FO satellites but will see improvements in design. This includes a atom-bomb instrument (MWI) babelike on Global Positioning System (GPS) technology. The MWI system measures the distance between the satellites centers of mass and s discharge changes in distance represent gravitational changes (Tapley, 2008). A very sensitive accelerometer meant to measure the forces acting on the satellites besides gravity including atmospheric drag will also remain (Tapley, 2008). There were introductory accelerometer errors and satellite-to-satellite measurement errors that will be reduced by the lower stature and updates in design on the follow-on mission (Loomis, Nere m, and Luthcke, 2012).The microwave ranging system utilize commode measure the distance between satellites to within one micron or about the diameter of one human blood stall (NASA JPL, 2017). It is kn aver as a KBR system because it utilizes microwaves in the K (26 GHz) and Ka (32 GHz) frequence channels (Jiang et al., 2014). Distance measurements between the two satellites ar taken by monitoring the magazine of flight of microwave signals transmitted and received nearly simultaneously between the two spacecraft (Bao et al., 2005). Previously collected data and models created by scientists based on known gravitational differences linked to mountains and ocean trenches, the location of the sun, and the flow of the tides argon compared to new measurements of the satellites to interpret gravitational changes (NASA JPL, 2017). Also, the GPS building block on board is apply in tandem with the MWI to be able to understand the gravity field below and can accurately depute captur e time to data (Sheard et al., 2012).The accelerometer can then measure non-gravitational forces affecting the satellite as previously mentioned including atmospheric drag and solar radiation sickness syndrome pressure (Schutze, 2016). These additional forces are then subtracted from measurements taken by the MWI. At the low altitude of orbit of GRACE comes changing solar radiation and large thermal disturbances to on-board instruments (Schutze, 2016). As a result, one improvement to the accelerometer on the GRACE-FO satellites will be placing the measurement digitalization unit in a temperature controlled area of the spacecraft to prevent temperature variation that can make data inaccurate (Christophe et al., 2015).The FO mission will include new technology known as a optical maser interferometer that will make measures that are at least 25 times more precise than the on-board microwave ranging system due to shorter wavelength usage (Sharing, 2017). The LRI uses an active trans ponder principle, which mover that the weak accounting entry received (RX) beam to the trailing satellite is replaced by a inviolate local oscillator (LO) beam. The LO beam is then reflected back to the lead satellite by a Triple Mirror Assembly (TMA) which directs the beam and influences the amount of light returned (Fledderman et al., 2014). It also serves to effectively route the incoming beam around other important hardware pieces (Fledderman et al., 2014).The use of the new laser interferometer represents the first time an active laser ranging system will be act upond between two spacecraft (NASA JPL, 2017). However, the microwave system will remain intact to project continuity of data from the first mission and the use of interferometer represents notwithstanding a technology demonstration (Sharing, 2017). While some studies found the LRI technology could greatly increase the accuracy of gravity data, others found that there would be only moderate improvements in the acc uracy models (Flechtner et al., 2015). However, seeing the results of the two systems as they operate simultaneously will create meaningful data for the planning of emerging of gravity field missions.The GRACE-1 mission allowed for new breakthroughs in the fields of hydrology, oceanography, glaciology, geophysics, and geodesy (Sharing, 2017). Since gravity is determined by mass, the GRACE systems have the capability to show how mass is distributed around the planet (Sharing, 2017). However, GRACE has and will reside to have no vertical resolution and can therefore, not distinguish between surface water, soil moisture, and ground water (Bolton and Thomas, 2015). Land surface models therefore allow for the disaggregation of Terrestrial Water Storage (TWS) data by separating these data into layers with known points of distinction (Bolton and Thomas, 2015). For example, in a study of the High Plains voice of the US, the discrepancy of snow and surface water were found to make insigni ficant contributions to TWS variability compared to groundwater and soil moisture changes (Ward, 2003). Therefore, removing moisture data known from previous studies of the area allowed scientists to subtract these figures from the GRACE gravitational measurements to understand changes in groundwater levels over time (Ward, 2003). Over time, improvements in GRACE data bear on have allowed for the sleuthing of changes in TWS within 1.5 cm accuracies for a wide range of spatial and seasonal scales (Jiang et al., 2014).(Ward, 2003)Measuring changes in global mass distribution can help scientists across many disciplines. GRACE data has also been used to observe increases and decreases in the ice and snow masses of glaciers and changes to the solid Earth following seismic activity often(prenominal)(prenominal) as the Fukushima landed estatequake of 2011 in Japan (Flechtner et al., 2016). Ocean water elevation changes caused by the devastating 2004 Sumatra tsunami had an jounce of the inter-satellite distance of the GRACE satellites and showed how oceanic mass redistribution can affect Earths gravity field (Bao et al., 2005). Due to the relatively low spatial resolution of GRACE data, it is more useful for monitoring large-scale unremarkable water changes such as in past studies of the entire Amazon Basin or India (Bolton and Thomas, 2015). Other applications include flood and drought monitoring for management projects and interventions (Bolton and Thomas, 2015). For example, the US National Drought Mitigation Center uses GRACE data monthly to generate drought indicators and monitor surface water changes (NASA JPL, 2016). GRACE data also allows for the study of changes in deep ocean currents by quantity pressure changes at great depths. Similar pressure changes in the structure of the solid earth can be studied as swell (NASA JPL, 2016).Trends in TWS and water mass redistribution made possible from GRACE data from 2002-2013(Bolton and Thomas, 2015)One of the benefits of an active satellite system such as the GRACE-1 and GRACE-FO compared to motionless systems is that it can collect accurate data 24 hours per day because it creates its own source of electromagnetic energy (Schowengerdt, 2006). Also, the use of microwaves in the GRACE missions means that data is not affected by any type of demoralise cover which often greatly affects accurate passive sensor data acquisition because the system only considers inter-satellite distance and GPS location for data retrieval. dynamical sensors dependent on microwave signals like on the GRACE missions are unique in their capabilities. The launch of the first GRACE mission allowed for data on earths geoid that was 100 to 1000 times more accurate than previous models could estimate depending on the region of the global under consideration (Ward, 2003). GRACE data has also allowed scientists to under the impact of global climate change based on mass redistribution of water around the globe in a comprehensive and consistent manner never previously achieved. With more accurate data from the GRACE-FO mission and the security of continued data creation, changes caused by climate change will continue to be monitored and planning for goings such as drought can be improved.However, compared to passive system data, the summary of data is more complex and costly overall. The data output of the GRACE systems also requires a lot of manipulation and filtering to create meaningful datasets for a variety of disciplines. The microwave region of the electromagnetic spectrum is far from the visible region and therefore, the resulting data is also less intuitive for human interpretation (Schowengerdt, 2006). The crude(a) data outputs for GRACE are just inter-satellite distance measurements and GPS data about satellite location (Ward, 2003).Therefore, improvements in satellite technology components alone will not improve the data created by GRACE. Improvements also need to be made to th e many geophysical models used in data bear upon (Loomis, Nerem, and Luthcke, 2012). For example, a complete global depiction of the earths gravity field is only available every 30 days while forces such as tidal shifts can change on a minute-to-minute basis. This difference creates an issue in which short-term differences are lost or their impact is underestimated (Sheard et al., 2012). Therefore, concord gravitational influences not directly linked to mass balance changes is essential.Models of gravity field anomalies on earths geoid created by comparingGRACE data from two different temporal scales (Ward, 2003)Models based on GRACE data are also curb by the noise present in the system data. This noise is linked to instrument errors, uncertainties in background models, and limitations in processing strategies (Siemes et al., 2013). In order to make meaningful measurements of mass changes on the earth using GRACE data, the noise of resulting models needs to be kept at a minimum, usually accomplished by applying filters (Siemes et al., 2013). However, when one problem is solved, other potentially arises. Filtering suppresses noise and blurs the signal, limiting the spatial resolution so much that part of the leak may affect nearby regions and cause errors in mass redistribution data (Siemes et al, 2013). However, more complex filtering methods have been developed to also minimize the blurring of data.Also, the spatial resolution of GRACE data is ultimately limited (Siemes et al., 2013). The spatial range for very accurate GRACE data application was 400km to 40,000 km for the first mission (Tapley, 2008). The strength of GRACE data therefore lies in an ability to monitor mass changes over time instead than to understand the water storage in one area at a specific time. However, there is potential for the lower altitude of the GRACE-FO mission and the LRI technology utilization of shorter wavelengths to allow for higher spatial resolution.The GRACE mission h ave shown that the use of active sensor technology on earth system satellite missions that utilizes microwave laser instruments and likely laser interferometers is fantastically efficient at understanding changes in earths geoid. With the launch of the GRACE-FO mission subsequently this year, even more accurate measurements and greater understanding of mass redistribution of water around the planet will be possible. Despite the rapidly changing and unpredictable political climate of the United States government, the launch of the GRACE-FO mission seems undeterred and the collection of important data related to climate change-related issues will continue to be gathered.ReferencesBao, L.F., Piatanesi, A., Lu, Y., Hsu, H.T., and Zhou, X.H. 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