Space Exploration

Introduction

Space is a very low density of particle in boundless three-dimensional extent vacuum filled with cosmic rays, radiation, magnetic fields and neutrinos. Progress to send manned mission to Moon and Mars has heated up with programme like Artemis and Chinese Lunar Exploration Program (CLEP). The Artemis program shows great potential to deliver crewed mission by 2024 with hinted budget as much as $35 billions [ref].

Satellite

Natural Satellite

Moon

Artificial Satellite

Usable artificial satellite

Mission to Moon

Luna 2

4 October 1959 - First spacecraft to reach lunar surface.

Apollo 11

16 July 1969 - First crewed landing on the Moon.

Mission to Mars

Space Technology in Singapore

Singapore Space and Technology Association (SSTA)

Singapore Space Challenge

Space Academy Singapore

Space Research Laboratory / Entities in Singapore

Satellite Research Centre, EEE, NTU [link]
Satellite Department, I2R [link]

Publications

Highly Cited Satellite Articles

W. H. F. Smith, and D. T. Sandwell , " Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings," Science, vol. 277, no. 5334, pp. 1956-1962, Aug 2012. DOI: 10.1126/science.277.5334.1956

Abstract: A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor.

W. H. Clohessy, and R. S. Wiltshire, " Terminal Guidance System for Satellite Rendezvous," Journal of the Aerospace Sciences, vol. 27, no. 9, pp. 653-658, Aug 2012. DOI: 10.2514/8.8704

Short Abstract: This paper assumes a requirement for an unmanned multi unit satellite to be assembled in orbit. The requirement to be met is to bring satellites together so that they do not collide but actually rendezvous.

O. Montenbruck, E. Gill, and F. H. Reviewer, " Satellite Orbits: Models, Methods, and Applications," Appl. Mech. Rev., vol. 55, no. 2, pp. B27-B28, Mar. 2002. DOI: 10.1115/1.1451162

Abstract: This book is intended to be a “comprehensive textbook that guides the reader through the theory and practice of satellite orbit prediction and determination.” This reviewer believes the book does just that. However, it is stated that it is intended for advanced undergraduate or graduate courses, and for professionals on the job. The undergraduate would likely have to struggle with the material presented in the book for two reasons. One is that s/he would not have a sufficient background in all the areas covered, and the other is that a significant amount of material is presented in such a concise form that it does not allow one to pick up the background material from the text. The diligent student, however, could refer to the ample references provided (approximately 320) to fill in the background gaps. The author’s focus is on providing material currently being used for orbit prediction and determination. (A good portion of the references are from the 1990s.) There is little, if any, discussion of analytic approaches (such as perturbation techniques) that classically have been applied to such problems. There is an extensive amount of practical information regarding force modeling, measurements and filtering, tracking, reckoning time, and computer algorithms.

Richard W. Reynolds, W. Richard, Nick A. Rayner, Thomas M. Smith, Diane C. Stokes, Wanqiu Wang, "An Improved In Situ and Satellite SST Analysis for Climate," Journal of Climate, vol. 15, no. 13, pp. 1609-1625, Jul. 2002. DOI: 10.1175/1520-0442(2002)015%3C1609:AIISAS%3E2.0.CO;2

Abstract: A weekly 1° spatial resolution optimum interpolation (OI) sea surface temperature (SST) analysis has been produced at the National Oceanic and Atmospheric Administration (NOAA) using both in situ and satellite data from November 1981 to the present. The weekly product has been available since 1993 and is widely used for weather and climate monitoring and forecasting. Errors in the satellite bias correction and the sea ice to SST conversion algorithm are discussed, and then an improved version of the OI analysis is developed. The changes result in a modest reduction in the satellite bias that leaves small global residual biases of roughly 0.03°C. The major improvement in the analysis occurs at high latitudes due to the new sea ice algorithm where local differences between the old and new analysis can exceed 1°C. Comparisons with other SST products are needed to determine the consistency of the OI. These comparisons show that the differences among products occur on large time- and space scales with monthly rms differences exceeding 0.5°C in some regions. These regions are primarily the mid- and high-latitude Southern Oceans and the Arctic where data are sparse, as well as high-gradient areas such as the Gulf Stream and Kuroshio where the gradients cannot be properly resolved on a 1° grid. In addition, globally averaged differences of roughly 0.05°C occur among the products on decadal scales. These differences primarily arise from the same regions where the rms differences are large. However, smaller unexplained differences also occur in other regions of the midlatitude Northern Hemisphere where in situ data should be adequate..

I2R Satellite Articles

Nasimuddin, Xianming Qing, and Zhi Ning Chen, "A wideband circularly polarized microstrip array antenna at Ka-band," in Proc. of 10th European Conference on Antennas and Propagation (EuCAP), pp. 1-4,Apr. 2016. DOI: 10.1109/EuCAP.2016.7481214

Abstract: A circularly polarized microstrip array antenna is proposed for Ka-band satellite applications. The antenna element consists of an L-shaped patch with parasitic circular-ring radiator. A sequentially rotated 2×2 antenna array exhibits a wideband 3-dB axial ratio bandwidth of 20.6% (25.75 GHz - 31.75 GHz) and 2;1-VSWR bandwidth of 24.0% (25.5 GHz - 32.5 GHz). A boresight gain of 10-11.8 dBic is achieved across a frequency range from 26 GHz to 32 GHz. An 8×8 antenna array exhibits a boresight gain of greater than 24 dBic over 27.25 GHz-31.25 GHz.

Nasimuddin, Xianming Qing, and Zhi Ning Chen, "A Compact Circularly Polarized Slotted Patch Antenna for GNSS Applications," IEEE Transactions on Antennas and Propagation, vol. 62, no. 12, pp. 6506-6509, Dec. 2014. DOI: 10.1109/TAP.2014.2360218

Abstract: A compact circularly polarized (CP) square-ring slotted patch antenna with vias is proposed for global navigation satellite systems (GNSS). Four square-ring-shaped slots are cut symmetrically onto a square patch radiator along its diagonals for wide-angle CP radiation and miniaturization. The antenna size is further reduced by grounding the central patches surrounded by the square-ring-shaped slots. An antenna prototype with an overall size of 60 mm × 60 mm × 5 mm shows a measured 10-dB return loss bandwidth of 90.0 MHz (1.565-1.655 GHz) with a maximum gain of 4.65 dBic. The measured 3-dB axial ratio (AR) bandwidth is 35.0 MHz (1.57-1.605 GHz) with a 3-dB AR beamwidth of more than 140 ° across the bandwidth.

References

Jessica Snouwaert (2020, Feb. 13). To rocket Americans back to the moon in 2024, NASA says it needs an additional $35 billion over the next 4 years. Retrieved Feb. 28, 2020 from Business Insider Singapore
Lester Kok (2019, Jan. 23). NTU Singapore's ninth satellite successfully deployed in space. Retrieved Feb. 28, 2020 from EurekAlert
Rachel Genevieve Chia (2019, Jan. 22). NTU just launched a satellite with an insane camera and plasma thrusters into space – and its only job is to take a photo of a dramatic phenomenon. Retrieved Feb. 28, 2020 from Business Insider Singapore

Keywords

Ka-band, GNSS, space technology, space science, moon, space station, I2R satellite, antenna, NTU, earth science, ocean, singapore