Radar Technologies for Earth Remote Sensing From CubeSat Platforms

Peral, Eva; Im, E.; Wye, L.; Lee, Simon; Tanelli, Simone; Rahmat‐Samii, Y.; Horst, Stephen; Hoffman, Jim; Yun, Sang‐Ho; Imken, Travis; Hawkins, David

doi:10.1109/jproc.2018.2793179

Cited by 89 publications

(29 citation statements)

References 32 publications

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“…The unique sampling offered by closely-spaced (p, q and T) profiles obtained from RO is complementary to other small satellite-based observations of the cloud structure as obtained from space-based radar, such as the RainCube Ka-band radar currently (mid-2019) being tested from space [46]. RO obtained by compact, low-power Cion-sized instruments could orbit together with small high-frequency (e.g., 183 GHz water vapor complex) passive MW sounders on the same platform, or separately in formation flying.…”

Section: Discussionmentioning

confidence: 94%

Benefits of a Closely-Spaced Satellite Constellation of Atmospheric Polarimetric Radio Occultation Measurements

Turk

Padullés

et al. 2019

Remote Sensing

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The climate and weather forecast predictive capability for precipitation intensity is limited by gaps in the understanding of basic cloud-convective processes. Currently, a better understanding of the cloud-convective process lacks observational constraints, due to the difficulty in obtaining accurate, vertically resolved pressure, temperature, and water vapor structure inside and near convective clouds. This manuscript describes the potential advantages of collecting sequential radio occultation (RO) observations from a constellation of closely spaced low Earth-orbiting satellites. In this configuration, the RO tangent points tend to cluster together, such that successive RO ray paths are sampling independent air mass quantities as the ray paths lie "parallel" to one another. When the RO train orbits near a region of precipitation, there is a probability that one or more of the RO ray paths will intersect the region of heavy precipitation, and one or more would lie outside. The presence of heavy precipitation can be discerned by the use of the polarimetric RO (PRO) technique recently demonstrated by the Radio Occultations through Heavy Precipitation (ROHP) receiver onboard the Spanish PAZ spacecraft. This sampling strategy provides unique, near-simultaneous observations of the water vapor profile inside and in the environment surrounding heavy precipitation, which are not possible from current RO data. temperature vertical and horizontal structures in the surrounding region. Much of the water vapor resides in the 2 km nearest the Earth, the approximate top of the boundary layer, which is the layer where air motions are directly influenced by contact with the Earth's surface. However, increasing evidence points to the control of deep convection by the relatively smaller and more variable amount of moisture above the boundary layer, known as the free troposphere. When abundant, free tropospheric moisture can strengthen convection by making the atmosphere more unstable. Horizontal transport and the mixing of nearby dry air (through a process known as entrainment) can weaken the convection, by decreasing the buoyancy [2,3]. Free-tropospheric moisture thus appears to exert significant control on the development of deep convection, producing heavy precipitation [4][5][6][7][8][9][10][11].Currently, a better understanding of the cloud-convective process lacks observational constraints, due to the difficulty in obtaining accurate, vertically resolved pressure, temperature, and water vapor (denoted by p, T, and q, respectively) structure in and near convection. Infrared sensors, such as the Atmospheric Infrared Sounder (AIRS), provide water vapor structure outside of clouds and precipitation, but cannot estimate the water vapor inside clouds. Passive microwave (MW) sounding radiometers, such as the Advanced Technology Microwave Sounder (ATMS), operate in millimeter-wave (183 GHz) water vapor bands, which under heavy precipitation, are sensitive to the cloud top ice region [12], limiting their use in studies that require ...

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Section: Discussionmentioning

confidence: 94%

Benefits of a Closely-Spaced Satellite Constellation of Atmospheric Polarimetric Radio Occultation Measurements

Turk

Padullés

et al. 2019

Remote Sensing

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“…Indeed, lower frequency bands like S or L would lead to lesser prerequisites, but then the dimensions of the antennas would grow making less likely the hypothesis of nanosatellites. Still, the selection of S band for the nanosatellites CIRES [29] indicates that these solutions should not be discarded at all.…”

Section: Tomographic Formationsmentioning

confidence: 99%

Along-Track Multistatic Synthetic Aperture Radar Formations of Minisatellites

et al. 2020

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The paper analyses an along-track multistatic Synthetic Aperture Radar (SAR) formation. The formation aims at achieving a high azimuth resolution maintaining at the same time a large swath width. The case with one transmitting sensor and all receiving is analyzed (Single Input Multiple Output, SIMO). An effective and novel reconstruction, in the two-dimensional frequency domain is introduced that is able to keep low the azimuth ambiguity and achieve a recombination gain close to the theoretical one. Degradation of the system performance due to the loss of the control of formation position is analyzed using probabilistic considerations. Moreover, some innovative methods to mitigate the loss of optimality are introduced and evaluated using simulations. Finally, considerations on the impact of the across-track non zero baseline are discussed.

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“…In order to transmit the attitude, the CubeSat has to comprise a gyroscope to measure the angular rotation rate. This angular rotation rate is then filtered for obtaining a smooth signal via low pass filter to recompense random noise from the output of the gyroscope sensor . To get the attitude, the KF is used afterwards to integrate the angular rate.…”

Section: Ad and Control Systemmentioning

confidence: 99%

High‐precision attitude determination and control system design and real‐time verification for CubeSats

Gaber

Mashade

Aziz

2020

Int J Communication

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This paper presents the design and real-time verification of a high-precision and low-cost attitude determination and control system (ADCS) for CubeSat based on a micro-electro-mechanical (MEMS) gyroscope. The CubeSat new missions require accurate and sophisticated ADCS with attitude drift adjustment. Moreover, designing an effective ADCS for the CubeSat poses a difficult challenge. The satellite comprises of a two-unit CubeSat, which denotes that the ADCS is designed with small size, tight mass, and energy limitations. The ADCS has been enhanced in the former few years from fairly small resolution of 10 to around 0.6 m. This attitude drift, if not properly compensated, will cause a slow attitude information loss as the error in attitude rises between the actual and estimated. To correct the attitude adrift, the proposed system utilizes a MEMS gyroscope sensor which offers a comparative attitude to the Kalman filter for estimated attitude update. Real-time verification and validation for the ADCS are performed through Matlab/Simulink environment and lab testing to prove the efficacy of the proposed system. Simulation of the ADCS shows accurate results with error of no more than 1 . K E Y W O R D Sattitude determination, CubeSat, gyroscope, MEMS ADCS computer that holds the whole algorithms and the control schemes of the ADCS. The resolution of the ADCS is increased to around 0.6 m in the former 10 years. 6 The CubeSat U-class spacecraft 7 belongs to a category of reduced satellites that is mainly used in research and comprises several numbers of cubic elements. Moreover, the single largest step in reducing software cost is the usage of commercial, off-the-shelf (COTS) software. 8 This is analogous for the adoption of COTS microelectronics in space application. The CubeSats usually employ COTS in their structure: electronics design, and weights around 1.3 kg/unit. 9 For the control of the CubeSat, there are three phases after launch: de-tumbling, initial attitude determination (AD), and recursive AD. As the most prevalently used algorithms in satellite de-tumbling process, B-Dot controller controls the satellite by aligning it with the earth magnetic field vectors. Indeed, all small satellites used some variation of B-Dot as the controller for de-tumbling process. [10][11][12] As for preliminary AD, TRIAD method is one of the initial and simplest solutions to the spacecraft AD problem. This technique entails two sets of vectors: an observation vector from magnetometer and sun sensors, and a vector command for each observation according to its inertial reference frame. In 1977, Davenport presented the first successful application of Wahba's problem to spacecraft AD (as reported by Keat 13 ) using the quaternion parameterization of the direction cosine matrix (DCM) with the q-method algorithm. In 1979 (as reported by Shuster and Oh 14 ), the QUaternion estimator (QUEST) algorithm appeared as an alternative to the q-method. Although less robust than the qmethod, QUEST is the most used algorithm for Wahba's problem. 1...

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Radar Technologies for Earth Remote Sensing From CubeSat Platforms

Cited by 89 publications

References 32 publications

Benefits of a Closely-Spaced Satellite Constellation of Atmospheric Polarimetric Radio Occultation Measurements

Benefits of a Closely-Spaced Satellite Constellation of Atmospheric Polarimetric Radio Occultation Measurements

Along-Track Multistatic Synthetic Aperture Radar Formations of Minisatellites

High‐precision attitude determination and control system design and real‐time verification for CubeSats

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