Abstract: We present techniques for a machine learning approach to predict stellar classes of stars using their physical and observable characteristics. Stellar classification is the categorization of stars into spectral types and subclasses based on temperature, color, and various other properties, and it is a fundamental aspect of astronomy, providing vital insights into stellar properties and evolutionary stages. By taking the general class of a star (e.g., G2 being the Sun), our model leverages a diverse range of input features, such as luminosity, surface temperature, and color indices, to predict a star’s spectral class with viable accuracy. Among several implemented algorithms, Random Forest Classifier achieved an accuracy of 76% (log loss 0.69), outperforming other methods such as XGBoost (71%), K-Nearest-Neighbors (50%), and Logistic Regression (23%). We attribute the lower performance of XGBoost to overlapping threshold features and K-Nearest-Neighbors to the low linear correlations of the data. The results demonstrate the high potential of machine learning to automate feature classification within astronomy, such as spectral classification efficiently and with high accuracy, significantly enhancing our capacity to analyze large data sets in modern astronomy.

Abstract: Throughout the second part of the Modern Era, leading researchers in astronomy, physics and applied statistics into astrophysics have brought a novel hypothesis, in which it was speculated that the Milky Way will experience a clash with another galaxy as a result of an intersection in their motion. Currently, such a statement is purely speculative in nature, although specific signs that such a hypothesis reflects real-world phenomena have started appearing, which cover seemingly increased frequencies and extents of planetary and stellar alignments within the Milky Way. Any occurrence of such a phenomenon may be probable due to increased electromagnetic and gravitational influences from outside the galaxy, which may hint at an existing approach of a different galaxy towards the Milky Way. It may be important to mention that potential effects of a multi-galactic crash would involve a general polarisation of natural and spatial phenomena, given that a multi-galactic interaction and clash would involve a sharp, unprecedented increase in the extent of electromagnetic and gravitational fluctuations of influences toward the Earth, which would affect all natural phenomena upon it, including the climate, the weather, human and animal psychology and wellbeing, as well as the effects of seas and oceans upon nearby shores. Furthermore, if the hypothesis in which major electromagnetic and gravitational influences toward specific, earthquake-prone geographical areas of the Earth would increase the probability of the occurrence of novel earthquakes and aftershocks in such areas is proven to be evidence-based, then a multi-galactic clash involving the Milky Way could also result in a sharp increase in both the frequency and extent of earthquakes throughout the Earth. Furthermore, it could be that the increasing number of people “bumping” into numerical and geometrical coincidences of symmetry at random (i.e. an increasing number of people bumping into “angel numbers”) is a sign of existing increases in electromagnetic and gravitational influences from the cosmos, which may very well reflect a scenario of an approaching multi-galactic interaction that may in a lower probability scenario even implicate the Milky Way (i.e. perhaps with Andromeda in approximately 4.5 billion years). According to Albert Einstein’s Theory of Relativity, time is not an absolute entity, but a relative measure that can be contracted or dilated depending on the observer’s perspective. Nonetheless, such relativistic effects are technically imperceptible on Earth, just as passengers aboard a high-speed train experience stability and consistency within the train, regardless of its external speed. Similarly, the inhabitants of the Milky Way could remain unaware of significant relativistic changes in galactic motion, whilst natural and cosmic phenomena within the galaxy would paradoxically accelerate in a manner reflective to the acceleration of time, thereby “transforming” the 4.5 billion years potentially into a much shorter time frame. If the Multiverse is real, then the same analogy applies for the inhabitants of the Universe. Furthermore, it may be important to observe whether any double-exponential growth in the speed of the approaching galaxies has been taken into consideration, which would broadly shorten the duration of 4.5 billion years and also change the relativistic states of time within the implicated galaxies - whilst keeping the internal measurements of time intact. Any real-world application of such an analogy may bring implications that deeply intersect scientific and philosophical research, perhaps even offering a hypothesis in which traditional cosmological models that suggest an 11-billion year process of evolution of physical matter, may not be mutually exclusive with theological narratives, such as a “Seven-Day Creation”. Some hypotheses have even proposed a paradoxical existence of a relative state of the speed of light, although empirical scientific evidence states that it is an absolute value, which constitutes the foundation of Albert Einstein’s research. Such hypotheses could nonetheless operate according to the Philosophical model of “destroy the Temple and rebuild It afterward”, potentially resulting in the creation of the most foundational type of a paradox in which the speed of light would be deemed as both relative and absolute, which could constitute “the paradox of all paradoxes”. Effects of any multi-galactic interaction implicating the Milky Way may accelerate the production of more stars and planetary systems, and preserve existing forms of life, given that a clash between Sagittarius Dwarf and the Milky Way may have resulted in the creation of the Solar System. Or, such an interaction deemed to probably occur, and in the distant future, could describe religious passages in which a phenomenon of “star falling” is mentioned, which could also involve an increasing number of asteroids falling upon Earth, given that fluctuations in gravitational influences could cause asteroids from the great belt nearby Jupiter to change their direction, leading to increased statistical probabilities that more asteroids will change their direction and be headed toward the Earth. Such a phenomenon could be deemed as “beyond monumental” in nature and even impact the state of time within the interacting galaxies, given its relative nature - potentially accelerating it considerably as the galaxies approach one another, in proportion with the level of fluctuations in electromagnetic influences toward the Solar System. Overall, the effects of a multi-galactic clash could either create more life or be catastrophic for human and animal life, potentially resulting in a phenomenon of unprecedented population loss in all life forms. Likewise, it may be important for research efforts to continue in order to determine whether the Milky Way is indeed in the course of experiencing an unprecedented intersection with a different galaxy, as well as for scientists, local and international authorities to devise plans of preparation for the purpose of precaution and ensuring that all guidelines of Health & Safety are met in case of any increased frequency and extent of natural disasters throughout the Earth, whilst keeping academic and scientific perspectives in an optimistic realm, based on the available evidence.

Abstract: We propose the Fractal Electromagnetic Hierarchy with Resonant Scaling (FEH-RS) model, a novel framework unifying the interaction of magnetic (unseen) and electric (physical) realms through fractal patterns, frequencies, and harmonics across scales. Extending Maxwell’s unification of electromagnetism, FEH-RS reveals 3-6-9 resonances dominating macro scales and phi (φ ≈ 1.618) resonances dominating micro scales, governed by mathematics. We validate the model using extensive datasets: Cosmic Microwave Background (CMB), Cosmic Infrared Background (CIB), Galactic Center (Hubble Full Field), brain waves, biophotons, and hydrogen spectral lines, all showing clear frequency and fractal structures. A significant finding in the CIB—a dense bottom 1/3 section distinct from the top 2/3—may mark the dark energy influx ~5 billion years ago, aligning with cosmological timelines. Applied to a 100 MW AC generator, FEH-RS optimizes resonant energy transfer, offering a new standard for energy systems, cosmology, and biology.

Abstract: This paper thoroughly investigates lunar space weather, highlighting the complex dynamics and proposing a groundbreaking solution in the form of a Novel mission proposal called the Lunar Space Weather Observatory (LSWO) mission. Through meticulous analysis, various factors influencing the lunar environment, including solar activities, cosmic rays, and micrometeoroids, are examined to showcase their impact on the lunar surface and its environment. The paper outlines the LSWO mission's objectives, instrument payloads, and scientific rationale, emphasising its potential to bridge knowledge gaps and facilitate more informed decision-making in future lunar missions. Furthermore, the implications of understanding advanced lunar space weather are discussed, focusing on its relevance for future lunar communications and habitat establishment. The role of the LSWO mission in enhancing communication systems, ensuring astronaut safety, and optimising resource utilisation strategies are underscored, highlighting its significance for the sustainability and success of future lunar exploration endeavours. Overall, the paper offers a comprehensive overview of lunar space weather and proposes a pioneering solution that can significantly contribute to our understanding of lunar space weather and enhance the prospects of successful lunar exploration.

Abstract: Small object detection remains a challenge in remote sensing field due to feature loss during downsampling and interference from complex backgrounds. A novel network, termed SEMA-YOLO, is proposed in this paper as an enhanced YOLOv11-based framework incorporating three technical advancements. By fundamentally reducing information loss and incorporating a cross-scale feature fusion mechanism, the proposed framework significantly enhances small object detection performance. First, the Shallow Layer Enhancement (SLE) strategy reduces backbone depth and introduces small-object detection heads, thereby increasing feature map size and improving small object detection performance. Then, the Global Context Pooling-enhanced Adaptively Spatial Feature Fusion (GCP-ASFF) architecture is designed to optimize cross-scale feature interaction across four detection heads. Finally, the RFA-C3k2 module, which integrates Receptive Field Adaptation (RFA) with the C3k2 structure, is introduced to achieve more refined feature extraction. SEMA-YOLO demonstrates significant advantages in complex urban environments and dense target areas, while its generalization capability meets the detection requirements across diverse scenarios. Experimental results show that SEMA-YOLO achieves mAP50 scores of 72.5% on the RS-STOD dataset and 61.5% on the AI-TOD dataset, surpassing state-of-the-art models.

Abstract: An estimate of the trigger effect of the proton flux on seismicity is obtained. The proton flux time series with a time step of 5 minutes, 2000-2024, is analyzed. In each time interval of 5 days, statistics of the proton flux time series are calculated: mean values, logarithm of kurtosis, spectral slope, singularities spectrum support width, wavelet-based entropy and the Donoho-Johnston wavelet based index. For each of the used statistics, time points of local extrema were found and for each pair of time sequences of proton flux statistics and earthquakes with a magnitude of at least 6.5 in sliding time windows, the "advance measures" of each time sequence relative to the other were estimated using a model of the intensity of interacting point processes. The difference between the "direct" measure of the advance of time points of local extrema of proton flux statistics relative to the time moments of earthquakes and the "inverse" measure of the advance was calculated. The maximum proportion of the intensity of seismic events for which the proton flux is a trigger is estimated as 0.28 for using the points of the local minima of the singularities spectrum support width.

Abstract: The equation of time (EoT) tracks daily deviations in length between the solar day and the mean day. Since the length of the mean day remains constant throughout the year, the EoT must mirror daily fluctuations in the length of the solar day. Furthermore, if the Sun meridian declination (SMD) is dynamically linked to Earth’s rotational speed (ERS) the EoT must obey to oscillations in ERS. This document examines the position, velocity, acceleration, and net drive of the mean-time Sun within a solar sundial noon analemma considering both its vertical and horizontal dimensions: the SMD and the EoT. Evidence supports that ERS decreases monotonically along two trans-equinoctial analemmatic phases in which the net drives of the EoT and SMD become coordi-nated (either both accelerating or both decelerating) within the SMD interval of −16 to +19 arcdeg, centered at +3. Conversely, ERS increases monotonically along two trans-solstitial analemmatic phases in which the net drives of the EoT and SMD become opposed, outside the specified interval of SMD. The ERS reaches its minima and maxima at the troughs and crests of the EoT.

Abstract: The theory of orbital forcing as formulated by Milankovitch involves the mediation by the advance (retreat) of ice sheets and the resulting variations in terrestrial albedo. This approach poses a major problem, that of the period of glacial cycles which varies over time as happened during the Mid-Pleistocene Transition (MPT). Here, we show that various hypotheses are called into question because of the finding of a second transition, the Early Quaternary Transition (EQT) resulting from the million-year period eccentricity parameter. We propose to complement the orbital forcing theory to explain both the MPT and the EQT by invoking the mediation of western boundary currents (WBCs) and the resulting variations in heat transfer from the low to the high latitudes. From observational and theoretical considerations, it appears that very long period Rossby waves winding around subtropical gyres, the so-called “gyral” Rossby waves (GRWs), are resonantly forced in subharmonic modes from variations in solar irradiance resulting from the solar and orbital cycles. Two mutually reinforcing positive feedbacks of the climate response to orbital forcing have been evidenced, namely the change in the albedo resulting from the cyclic growth and retreat of ice sheets in accordance with the standard Milankovitch theory, and the modulation of the velocity of the WBCs of subtropical gyres. Due to the inherited resonance properties of GRWs, the response of the climate system to orbital forcing is sensitive to small changes in the forcing periods. For both the MPT and the EQT, the transition occurred when the forcing period merged with one of the natural periods of the climate system. The MPT occurred 1.25 Ma ago when the dominant period shifted from 41 ka to 98 ka, with both periods corresponding to changes in the Earth's obliquity and eccentricity. The EQT occurred 2.38 Ma ago when the dominant period shifted from 408 ka to 786 ka, with both periods corresponding to changes in the Earth's eccentricity. By providing new information, the aim of this article is essentially to spark new debates around a problem that has been pending since the discovery of glacial-interglacial cycles, where many hypotheses have been put forward without, however, fully answering all our questions.

Abstract:

The research uses data from the Mini-TES infrared spectrometer of the Opportunity rover taken at selected locations along its route on Meridiani Planum on Mars. Using emissivity data, the corresponding mineralogical compositions were calculated. Generally, the results are consistent with previous works, in particular they indicate the widespread occurrence of clay minerals and minerals from basaltic rocks. However, several interesting facts were also noted. Among other things, clear changes in the hematite content were found, suggesting that on certain area spherical concretions (known as blueberries) may be devoid of hematite. A similar phenomenon is known from studies of terrestrial concretions. Moreover the possibility of pyrite existence was found on a certain section of the route. On Earth, pyrite often occurs with economically valuable minerals.

Abstract: Solar flares, originating from sudden energy releases in the Sun’s atmosphere, pose significant risks to spaceborne and terrestrial technological systems, including satellite operations, communications networks, and power grids. Accurate solar flare forecasting is therefore essential for mitigating these impacts and advancing space weather prediction capabilities. In this study, we present a comprehensive deep-learning-based approach utilizing multi-channel observations from the Solar Dynamics Observatory (SDO), a spaceborne remote sensing platform dedicated to solar monitoring. Our analysis focuses on classifying solar flares under three scenarios: C vs. 0, M vs. C, and M vs. 0, leveraging ten distinct image channels spanning photospheric magnetograms and extreme ultraviolet (EUV) wavelengths. We trained and evaluated three modern convolutional neural network architectures—ResNet50, GoogLeNet, and DenseNet121—using the True Skill Score (TSS) and Gini coefficient to assess performance. The results highlight the superior predictive power of magnetogram data, with additional contributions from EUV channels such as 94 and 211 Å. This work underscores the utility of combining multi-spectral solar observations with state-of-the-art deep learning architectures to capture subtle pre-flare signatures and improve flare prediction accuracy. Furthermore, the methodology and open dataset provide a reproducible benchmark for advancing solar flare forecasting, supporting the broader remote sensing and space weather research communities.

Abstract: The time period around the Noachian-Hesperian boundary, 3.7 million years ago, was an epoch when great geodynamical and environmental changes occurred on Mars. Currently available remote sensing data are crucial for understanding the Martian heat loss pattern and global thermal state in this transitional period. We here derive surface heat flows in specific locations based on estimations of the depth of five large thrust faults, in order to constrain both surface and mantle heat flows. Then, we use heat-producing elements (HPEs) abundances mapped from orbital measurements by the Gamma-Ray Spectrometer (GRS) onboard Mars Odyssey 2001 spacecraft, and geographical crustal thickness variations, to perform a global model for the surface heat flow. The heat loss contribution of large mantle plume beneath the Tharsis and Elysium magmatic provinces is also considered for our final model. We thus obtain a map of the heat flow variation across the Martian surface at the Noachian/Hesperian boundary. Our model also predicts an average heat flow between 32 and 50 mW m−2, which implies that the heat loss of Mars at that time was lower than the total radioactive heat production of the planet, which has profound implications for the thermal history of Mars.

Abstract: Two centuries after Carnot defined thermodynamics as a scientific discipline based on work by engineers like James Watt, can we learn more from Carnot’s perceptive analysis of maximum power from heat engines? Using action mechanics, the rate of work in Carnot’s heat engine cycle can be integrated as external pressure-volume work, sustained by internal quantum field work, equal to changes in Gibbs free energy that was called caloric by Carnot. His treatise of 1824 even gave equations that express the work potential as a function of temperature and the logarithm of the change in volume. To answer this question, we apply Carnot’s principle defined by Clausius as entropy, to atmospheric heat-work cycles, such as in anticyclones. We show using Lagrange’s virial theorem how Carnot’s thermodynamic states as Gibbs potential become entangled with gravitational potential states. The effective capacitance of greenhouse gases for energy in the troposphere enable recycling of heat emitted from the Earth’s hot surface, thermally setting tropospheric air masses in action. By delaying irreversible emission of long wavelength quanta to space, this recycling process extends the residence time of solar energy in the troposphere as work, maximising troposphere entropy to the tropopause. The virial theorems of Lagrange and Clausius, governed on the principle of least action, provide a more accurate lapse rate in temperature with temperature in the atmosphere, replacing the paradigm of adiabatic expansion. Reversible 4-stage Carnot cycles, based on Lagrangian least variation in action, raise surface temperature and pressure from turbulent heat release, sustaining the weight of the atmosphere. New lessons for understanding climate dynamics are emerging from this virial-action analysis.

Abstract: Determining match pairs among disordered images is a prerequisite for constructing tie points and control networks for the bundle adjustment of planetary remote sensing images. The efficiency and accuracy of determining image match pairs greatly affect the performance of generating planetary mapping products and three-dimensional models. However, existing methods for determining image match pairs in the field of planetary mapping generally use exhaustive methods (such as the USGS ISIS software), which are extremely inefficient when processing a large number of images. This paper proposes an efficient method of image overlapping relationship analysis based on the spatial index of KD tree fast search for disordered and large-scale asteroid images. The algorithm first calculates the three-dimensional coordinates of the image center point, constructs a KD tree data structure based on the three-dimensional coordinates of each image center, and then uses the KD tree fast search algorithm to quickly find the image overlapping relationships within the spec-ified spatial range. For situations where the entire celestial body only occupies a local area of the remote sensing image during the approach stage of asteroids, the center of the effective pixels in the image is calculated by the ray intersection of sampling points. In this study, the image data from asteroid exploration missions such as Bennu, Vesta, and Ryugu are used for experiments, and the proposed image match pairs determination algorithm is systematically compared with the corre-sponding modules of USGS ISIS in order to evaluate its performance in terms of efficiency and accuracy. The results show that when processing more than a thousand images, the proposed method is two to three orders of magnitude higher in efficiency than the corresponding module in USGS ISIS while ensuring the correctness of the image overlapping relationships and the accuracy of bundle adjustment, with the advantage becoming clearer as the amount of data increases. At the same time, according to the obtained image match pairs, images that meet the requirements of Stereo Photoclinometry can be quickly and preferably selected, effectively improving the quality of 3D reconstruction models of asteroid images.

Abstract: Valles Marineris (VM), the most prominent example of a Martian Valley Network, has been extensively studied for over 50 years, yet no detailed examination of the principal azimuths of the system exists. To address this, two methods are presented to precisely calculate the principal azimuths, a Bezier Spline analysis, and a GIS technique. The medial axis of the main canyon of VM was determined analytically from cubic polynomial splines fitted to 93 coordinate points along both north and south edges of the canyon. These splines were optimized, and medial axis points were calculated through numerical techniques that ensured orthogonality between the tangents of each spline and their connecting normal lines. 1,000 medial axis points were extracted, and various regression models constructed, including fitting to sinusoidal and cubic polynomial curves, achieving accuracies with R² values of 0.98 and 0.99, respectively. Principal azimuths were obtained using the sinusoidal equation with the slope of the tangent at any point x simply determined by the derivative of the curve’s equation. This analytic approach was cross-validated by a GIS method (using QGIS software), where a vector medial axis was obtained which produced principal azimuths that agreed with values from the analytic study with a correlation coefficient of 1.00, and a p value of 6.43e-65. The findings demonstrate that an azimuthal framework can be rigorously constructed as a potential standard reference in VM geoscience, replacing less precise and ambiguous compass bearings with the accurate azimuths necessary for high-resolution spatial analysis for future investigations.

Abstract: A novel method has been developed based on the amplitude data of the EM waves measured by Digisondes to calculate and investigate the relative ionospheric absorption changes. The effect of 13 solar flares (> C4.8) that occurred between 06:00 and 16:30 UT from 04 to 10 September 2017 have been studied at three European Digisonde stations (Juliusruh (54.63° N, 13.37° E), Průhonice (49.98° N, 14.55° E) and San Vito (40.6° N, 17.8° E)). Present study compares the results of the amplitude method with the absorption changes measured by the Finnish Riometer Network and determined by the NOAA D-RAP model during the same events. The X-class flares caused 1.5–2.5 dB attenuation at 30–32.5 MHz based on riometer data, while the absorption changes were between 10 and 15 dB in the 2.5–4.5 MHz frequency range according to the amplitude data. The impact caused by the energetic particles after the solar flares are clearly seen in the riometer data, while it can be observed only at Juliusruh (~55°) at some certain cases among the Digisonde stations. Comparing the results of the amplitude method with the D-RAP model it seems evident that the observed values exceed the values given by the model both at 2.5 MHz and at 4 MHz almost always during the investigated period. According to the comparison between the riometer data with the D-RAP, the model underestimates the values obtained from the riometers during the X-class solar flares, while it overestimates the caused impact during the particle events.

Abstract: One of the main challenges associated with spatial entities affected by potentially irreversible adverse development processes (depopulation and related changes in the population structure, economic difficulties, declining accessibility and quality of services, etc.) is coping with their consequences – taking a planned approach (as opposed to passive observation of spontaneous developments) towards mitigating adverse effects on the quality of life of the local population. Public services (healthcare, education, culture, etc.), as a fundamental human need in modern society, but also a warranty of a certain level of living quality, are particularly important in such areas. Apparently, it is necessary to accept the closing of a number of facilities as a reality, and to take a planned approach seeking to mitigate the negative effects on the life of the local population. This is a context of our research, where these services are taken as a universal human right and striving for their equitable availability as a goal of national spatial development policies. The starting point in our analysis of this issue observed through the lens of the Serbian national legal and planning framework is the spatial plan of a local self-government unit as the basic platform for defining and operationalising spatial development policies at the local level. It has been examined whether it would be possible to use the mathematical modelling of optimal spatial solutions as support in making decisions that would minimise the negative effects of the closure of a number of public service facilities. The results for the selected research area and the network of primary healthcare facilities show that it is possible to stabilise the accessibility of these facilities by modelling the spatial organisation of primary healthcare despite the expected closure of as much as one-third of the facilities, while any other solution would give more or less unfavourable results.

Abstract: The comparison of three types of ionosonde data from Europe during an Interplanetary Coronal Mass Ejection (ICME) and a Stream Interaction Regions (SIRs) / Corotating Interaction Regions (CIRs) -driven geomagnetic storm event is detailed in this study. The selected events are 16-20 March 2015 for the ICME-driven and 30 May to 04 June 2013 for the SIR/CIR-driven one. Ionospheric data from three European ionosonde stations, namely Pruhonice (PQ), Sopron (SO) and Rome (RO), are investigated. The ionospheric F2-layer responses to these geomagnetic events are analyzed with the ionospheric foF2 and h’F2 parameter, the calculated deltafoF2 and deltahF2 values, ratio of Total Electron Content (rTEC) and Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) satellite Global Ultraviolet Imager (GUVI) thermospheric [O]/[N2] measurement data. The storm-time and the quiet day mean values are also compared, and it can be concluded that the quiet day curves are similar at all stations while the storm-time ones showed the latitudinal dependence during the development of the storm. As a result of the electron density comparison, during the two events it can be concluded that SSC that characterized the ICME induced a Travelling Atmospheric Disturbance (TAD) seen in the European stations, while this is not in the SIR/CIR-driven ionospheric storm, which showed a stronger and more prolonged negative effect in all stations probably due to the season.

Abstract: Dust storms play a crucial role in the climate system and the space environment of Mars and have a great impact on human’s Mars exploration activities. The Martian dust storms exhibit significant regional, seasonal and interannual variations due to various controlling factors such as the large-scale atmospheric circulation, varying solar radiation forcing, and Martial orbital and rotational motions and their coupling to the atmospheric dynamics. This paper focuses on the review of cur-rent understandings on Martian dust storms. This paper begins by elucidating the basic properties of dust storms, and their driving mechanisms and impacts on atmospheric dynamics, atmospheric electric property, space environment, topography, and Mars explorations. Then it introduces the observation methods on different platforms including orbiters and landers/rovers, and the da-tasets constructed based on these historical observations for Martian dust storms. Finally, we pro-posed the dust storm monitoring and forecasting for the upcoming Chinese Tianwen-3 Mars sam-pling returning mission. It concludes by depicting the future research topics to systematically un-derstand the Martian dust storms.

Abstract: Assessing observation noise is a critical step in the development of a stochastic model for GNSS navigation and positioning. This process ensures that the statistical properties of the observational data are accurately characterized, leading to more reliable and precise positioning results. Traditionally, the one sigma values for observation noise, 0.3 m for code and 3 mm for carrier phase, alongside elevation-dependent weighting schemes, have been standard. However, these may no longer be suitable due to significant advancements in GNSS systems, receivers, and antennas. Previous research predominantly focused on code type and PPP techniques, often limited by the inability to separately assess observation types across different frequency bands due to ionospheric delay. Furthermore, these studies were generally constrained by limited experimental data. This research advocates for the use of ultra-short baselines to eliminate atmospheric delay and other error sources, providing a detailed assessment of observation noise for various frequency bands, GNSS systems, and receiver & antenna types over an extensive period and across multiple baselines. The findings suggest a need to reconsider traditional one sigma values and elevation-dependent weighting schemes for current applications.

Abstract: The space exploration landscape has transformed dramatically over the past several decades, with a significant rise in the number of annual launches. Key factors driving this increase include technological advancements, the miniaturization of satellites, and the surge in commercial satellite deployments for communication, Earth observation, and remote sensing. This paper examines the evolution of space activities from the launch of Sputnik 1 in 1957 to recent developments in commercial spaceflight and international collaborations. The paper discusses notable milestones in space exploration history, including early space missions, Apollo Moon landings, and the development of space stations like the International Space Station. It highlights the shift from state-led space programs to a more diverse landscape, characterized by private sector involvement and international partnerships. The "Space 4.0" phase, beginning around 2006, has seen the entry of commercial players like SpaceX, leading to a significant upsurge in orbital launches. Statistical data reveals an upward trend in launch activity, with over 200 launches in 2023 alone, driven by large satellite constellations like SpaceX's Starlink and the steady growth of China's space program. The increasing launch rate poses challenges such as space debris, emphasizing the need for mitigation strategies. Looking ahead, the paper projects a continued increase in launch activity, with over 150 launches expected annually by 2026 and 200-300 launches by 2040. Commercial space ventures, deep space exploration, lunar activities, and space tourism drive this growth. The paper concludes by emphasizing the importance of addressing space debris and promoting the long-term sustainability of space activities, which is crucial as humanity's presence in space continues to expand.