arXiv subjects

Slava G. Turyshev

Publications and source records attributed to Slava G. Turyshev.

At least 19 recordsLinked to original sources

arXiv2026

Sector-Resolved Bayesian Model Averaging for DESI-Era Cosmology

We present a quotient-space Bayesian formulation for DESI-era anomaly interpretation. Given a pattern-labeled catalog with map $i\mapsto \Act(i)$, the induced posterior $p(\Act\mid D)$, sector inclusion probabilities $P_α$, co-activation probabilities $P_{αβ}$, and grouped Bayes factors $B_α(D)$ are exact summaries over predeclared physical activation events. Pairwise comparisons such as $\lcdm$ versus $\wacdm$ remain ordinary Bayes-factor tests between specified families; the quotient construction addresses the coarser question of which physical sector carries posterior support when different sectors are represented by unequal numbers of catalog elements. We derive a sector-resolved DESI-CMB-SN likelihood specification for late-time background, early-time ruler, supernova calibration, perturbation, and gravitational-wave propagation sectors. The construction includes an Alcock-Paczynski/isotropic-scale BAO decomposition, a pure-ruler projection, analytic marginalization of low-rank supernova calibration modes, Fisher-normalized sector priors, inactive-sector leakage tests, log-evidence uncertainty propagation, and prior/sector-partition diagnostics. The result is a quantitative procedure for reporting model-comparison support at the level of physically interpretable sectors.

physics.gen-ph↗

arXiv2026

High-Power AM-CW Lunar Laser Ranging as a $μ$Hz SGWB Detector

High-power amplitude-modulated continuous-wave lunar laser ranging (AM-CW LLR) is a stochastic-gravitational-wave-background (SGWB) experiment that measures GW-driven drift and diffusion of the Earth--Moon orbit. Its observable is the coherent phase of a GHz modulation envelope returned by an individually resolved single hollow corner-cube retroreflector (HCCR), converted to absolute range and analyzed through its time-dependent mean and covariance. The response occurs at lunar orbital harmonics; the dominant low-eccentricity channel is centered at $f_2=0.847245\,μ{\rm Hz}$, and a five-year broadband forecast applies to spectra smooth over the resolution scale $T_{\rm obs}^{-1}=6.34\,$nHz about that resonance. A scalar 1-kW, 1064-nm link yields $5.893\times10^3$ detected photons s$^{-1}$ and an $88.8$--$124.3\,μ$m photon contribution in 100 s, while the forecasts adopt projected total range precisions of $80$ and $50\,μ$m. In the covariance-dominated weak-signal regime, $Ω_{\rm gw}^{95}\proptoσ_R^2\nuEff^{-1}T_{\rm obs}^{-4}$. Using the published Earth--Moon response normalization, the five-year 95\% thresholds are $1.86\times10^{-7}\Dtot$ for $80\,μ$m and $500\,{\rm yr}^{-1}$ and $2.42\times10^{-8}\Dtot$ for $50\,μ$m and $1500\,{\rm yr}^{-1}$, where $\Dtot$ is the full-analysis threshold divided by the unit-factor response-anchored forecast. If end-to-end calibration, sampling, and marginalization give $\Dtot\le1.15$, the higher-performance campaign reaches nominal source-statistic equality for $Ω_{\rm gw}=7.08\times10^{-8}$ in five years. These measurable performance and information-retention requirements define high-power AM-CW LLR as a standalone quantitative SGWB experiment at the $0.85\,μ{\rm Hz}$ Earth--Moon resonance.

gr-qc↗

arXiv2026

Do Quantum Measurement Advantages Survive to Astrophysical Inference? Seven Benchmarks in Optical Interferometry and Imaging

Quantum techniques matter to optical astronomy when they preserve information in the parameter-bearing measurement channel after realistic loss, calibration, covariance, and inference are propagated to the final astrophysical observable. We compare 7 approaches by the quantity they change: internal optical-path delay, sub-Rayleigh source separation, coronagraphic planet throughput & stellar leakage, coherent field quadratures, nonlocal complex visibility, null depth, active phase sensing. In an Earth-analog astrometry case, 6-dB squeezed internal metrology improves the measured phase quadrature by 1.58 and the complete readout by ~1.20, but fixed-time planet-mass precision by only 1.010 (95 % interval 1.005-1.045); mission duration, useful baseline, cadence, calibration have greater modeled leverage. For a close young binary, signed spatial-mode demultiplexing preserves sub-Rayleigh orbital information that is substantially degraded in the tested direct-imaging comparator. A representative matched-model calculation gives a dynamical-mass RMSE gain 1.77 1.47-2.15). For illustrative equal-prior pre-main-sequence predictions at 0.10 and $0.12M_\odot$, mass precisions of 15%, 10%, 7% correspond to correct-selection probabilities of ~73%, 82%, 90%. The numerical gain remains provisional because the event-level continuous-image comparator, strict tail convergence, externally measured broadband transfer matrix, and finite-photon calibration are not yet closed. Modal coronagraphy and quantum-enhanced heterodyne reception define conditional receiver opportunities, while the nonlocal, nuller, and prepared-NOON cases identify physical bottlenecks that prevent an astrophysical advantage in the stated configurations. The common result is that quantum technology is most valuable when it changes an information-bearing observable and that channel remains consequential in the final science measurement.

physics.gen-ph↗

arXiv2026

Operations, Maintenance, and Industrial Scaling of MW-Class Orbital Data Centers

Megawatt-class orbital data centers require continuous maintenance, replacement, inventory, and service capacity in addition to spacecraft power/thermal systems. We formulate an analytical lifecycle framework for permanent/transient failures, modular orbital replacement units, robotic servicing, spare inventory, scheduled technology refresh, correlated faults, cybersecurity, optional human support. The model combines nonhomogeneous component hazards, capacity-weighted availability, multiclass robotic-service capacity, Poisson base-stock inventory, replacement-flow accounting, human-support break-even relations. For a 1 MW cluster with 10 active 100 kW nodes, 1 reserve node, ~200 5 kW compute cartridges, low, nominal, high deployed-mass allocations span ~50-75 kg/kW. Assumptions yield 70.2 random or life-limited interventions and 323-349 planned refresh operations/(MW-year), for a total of 393-419 standardized operations/(MW-year). Analysis gives a first-generation logistics of 5.3-9.0 t/(MW-year), with a nominal case of ~ 6.6 t/(MW year), 560-700 productive robot-hors/(MW-year). Planned refresh exceeds random replacement under the stated component populations, hazards, 3-15-year intervals. At ~400 standardized operations/(MW-year), the post-internal-recovery exception probability is <$10^{-3}$, with an objective near $10^{-4}$ at large scale; terminal non-recovery $p_U$ requires a smaller mission-level allocation. The target catastrophic-loss hazard for a 100 kW node is 0.01-0.03 1/yr. Parametric workload and cost cases place contingency visits at 10s of MWs, periodic campaigns at 10-100s of MWs, dedicated personnel at several 100 MWs to GWs. The reference first deployment is uncrewed, autonomously fault-managed, robotically maintainable, supported by specific inventory based on a 6-month replenishment horizon, compatible with later human access without permanent habitation.

physics.gen-ph↗

arXiv2026

Quantum Technologies: System-Level Performance and Validation Priorities

Performance claims in quantum technology are not properties of hardware alone. They are properties of a declared task, system boundary, normalization denominator, uncertainty or security convention, and comparator. We perform a cross-domain analysis spanning quantum computing, simulation, communication, sensing, clocks, randomness generation, and their enabling technologies. The analysis changes substantive conclusions in several representative cases. For the longest direct finite-key quantum key distribution case analyzed here, the same final key gives rates differing by a factor of $1.91$ when normalized by complete acquisition rather than transmission-active time. In Advanced LIGO, $6.1\,\mathrm{dB}$ peak quantum-noise reduction coexists with a $0.534$ coincident analysis-ready fraction, separating detector-level gain from delivered observing service. In quantum computation and photonic sampling, matching the observable, error tolerance, loss model, sample count, amortization, and classical hardware moves or reverses published crossover claims. Across domains, the recurring limits are correlated error, multiplicative interface loss, thermal and nonequilibrium occupation, calibration covariance, measurement efficiency, fabrication yield, and control latency. A quantum advantage is therefore established only for a fixed task and boundary when the accepted output outperforms the best documented alternative at matched accuracy, elapsed time, availability, and lifecycle cost. The resulting framework identifies the measurements required to convert component records into reproducible system capability. Credible progress is defined by reproduced logical workloads, prospectively validated simulations, repeater links outperforming direct transmission, long-duration calibrated sensors and clocks, integrated hardware with predictable yield and reliability.

physics.gen-ph↗

arXiv2026

A Covariance-Aware Framework for Spatially Resolved Exoplanet Biosignature Inference with the Solar Gravitational Lens

Assessing possible life on an exoplanet requires spatial, spectral, temporal, and environmental context rather than a threshold detection of one molecule or surface feature. We develop a covariance-aware Solar Gravitational Lens (SGL) framework in which the data product is a time-tagged Stokes spectral cube reconstructed from wavelength-dependent Einstein-ring measurements. The demonstrated calculation is a 0.45-2.40 um Stokes-I reflected-light simulation of an Earth-radius planet at 30 pc, observed from 650 AU with a (128 x 128) raster, 128 simultaneous spectral channels, and $R\simeq70$. A separate 0.40-20 um architecture-level calculation tracks reflected and thermal planet photons, SGL gain, solar-corona noise, instrumental backgrounds, throughput, dwell time, and reconstruction covariance. In the controlled population audit, structural forward-model mismatch preserves the block ordering gas > surface > cloud/path > mineral > calibration/SGL while reducing the combined conditional information gain to 0.83 of the matched-model value. A reconstruction-covariance bracket reduces an (8 x 8) regional coadd gain from 7.77 to 3.00, implying a 6.7-fold dwell penalty. The feasibility results are design scalings, not a mission verdict: imaging and low-resolution mapping are earlier objectives, whereas full regional spectroscopy requires simultaneous acquisition, sub-ppm effective coronal calibration, measured reconstruction covariance, and branch-specific radiometric validation. We show that the SGL offers a uniquely powerful path to surface-resolved mapping, regional spectroscopy, thermal-climate diagnostics, and co-location tests, providing spatial, spectral, temporal, and environmental context that could strengthen assessments of habitability and possible biological activity beyond disk-integrated precursor observations.

astro-ph.IM↗

arXiv2026

Relativistic framework for high-precision GNSS processing in GCRS/BCRS with extension to cislunar space

We present an implementation-oriented relativistic modeling framework for high-precision {\tt GNSS} processing consistent with the IAU-adopted Barycentric and Geocentric Celestial Reference Systems (BCRS/GCRS) and their associated time scales (TCB/TDB and TCG/TT). We derive explicit ${\cal O}(c^{-2})$ transformations for position, velocity, and acceleration between TT-compatible GCRS quantities and TDB-compatible BCRS quantities, and provide screened operational forms with conservative remainder bounds that quantify state-map truncation errors for cm-class orbit modeling. For $10^{-16}$-class fractional-frequency transfer, the ${\cal O}(c^{-4})$ clock-rate terms identified below must be retained or explicitly included in the observable error budget. We implement a BCRS-native processing option in JPL's GipsyX and verify it internally via a 24~h round-trip GCRS$\rightarrow$BCRS$\rightarrow$GCRS propagation-and-transform closure test at the few-mm level, demonstrating consistency of the implemented dynamical model and state transformations under matched force-model assumptions. To support emerging Earth--Moon applications, we define a Lunicentric Celestial Reference System (LCRS), its coordinate time (TCL), and a scaled lunar-surface time (TL), and specify a minimal near-rectilinear halo orbit (NRHO)-like regression test that exercises the BCRS$\leftrightarrow$LCRS transformation chain together with the 1PN barycentric light-time model. End-to-end cislunar navigation performance additionally depends on signal availability and estimation strategy; the present work provides the relativistic reference-frame and time-transfer infrastructure needed to model observables at the centimeter and tens-of-picoseconds level.

gr-qc↗

arXiv2026

Optical Ground Stations for Space Communications:Systems Engineering, Availability, and Service Economics Through 2030

Optical ground stations (OGSs) are becoming networked infrastructure for high-rate space-to-Earth communications, but their adoption is governed by service availability and utilization as much as by optical line rate. This paper develops a systems-engineering and service-economics assessment of the OGS sector as of June~2026. The analysis combines public flight demonstrations and operational records with scalar link-budget, availability, and cost-normalization models. Public benchmarks span 25 Mbps from interplanetary range, 260 Mbps-class lunar links, 1.2 Gbps-class ISS relay, 1.8 Gbps operational GEO relay, 120 Gbps-class direct-to-ground demonstrations in China, and 200 Gbps from LEO in NASA's TBIRD mission. The resulting conclusion is that the bottleneck has shifted from peak line rate to repeatable service under weather, acquisition, scheduling, and operations constraints. Under one explicit planning normalization - a 10 Gbps near-Earth station, annualized cost of \$2 million/year, scheduled pre-weather optical contact time of 0.5 h/day, and weather-inclusive combined efficiency $η=0.7$ - the fixed-cost component is of order $(3-4)\times10^{3}$ USD/TB. This number is a sensitivity anchor, not a tariff forecast; the controlling variables are duty factor, effective weather diversity, shared-network loading, and service-level allocation. The public industrial evidence is best interpreted as a stratified value chain, not as a single vendor ranking. The defensible 2030 baseline is hybrid optical+radio-frequency (RF): optical for throughput, relay, and spectrum relief; RF for continuity, contingency, and assured command paths.

eess.SP↗

arXiv2026

Ultra-High-Resolution Astronomy with the Solar Gravitational Lens

The solar gravitational lens (SGL) is a target-specific observatory: the Sun supplies the wave-optical element, while spacecraft provide occultation, annular photometry, sampling, metrology, and inverse reconstruction. We develop an observability framework for non-exoplanet SGL astronomy. Viability is set by image-plane scale, raster pitch, finite-source gain, source-to-background ratio, temporal coherence, PSF knowledge, calibration, metrology, and focal-line access. We separate the vector Poisson measurement operator from the scalar convolution used for benchmarks. Four analytic scenes are propagated and reconstructed: a solar analog and magnetic white dwarf at 10 pc, an M87*-scale millimeter ring/jet source, and a bright 0.1 AU protoplanetary subfield at 140 pc. Under stated kernel-mismatch, background, calibration-floor, support-mask, sampling, regularization, and imposed information-floor assumptions, the scalar reconstructions give SSIM values of 0.993, 0.918, 0.973, and 0.923. These metrics quantify scalar inverse conditioning, not delivered flight performance; FRC50, support-leakage, and information-floor sensitivity diagnostics expose the dependence on assumptions. Many self-luminous compact targets are not photon-starved relative to a reflected-light exo-Earth reference, shifting the dominant requirements to ring extraction, coronal subtraction, detector dynamic range, PSF knowledge, cadence, spectroscopy, metrology, scan overhead, and access. The strongest bounded cases are white-dwarf surface and magnetic mapping, nearby stellar surfaces, compact AGN/black-hole structure with long-wavelength instrumentation, velocity-resolved broad-line-region mapping, and planet-forming subfields. The priority enabling program is SGL transfer-function characterization: measuring solar-multipole, plasma, extended-Sun, and instrumental response needed for scientifically interpretable imaging.

astro-ph.IM↗

arXiv2026

Gravitational lensing for interstellar power transmission

We investigate the propagation of monochromatic electromagnetic waves through multiple, well-separated, monopole gravitational lenses in the thin-lens/eikonal approximation. For the axially aligned transmitter--lens(es)--receiver geometry, the relevant diffraction integrals can be evaluated analytically, yielding closed-form expressions for the point-spread function (PSF) and for the aperture-averaged gain. A single gravitational lens can enhance transmission when it is used either at the transmitting end or at the receiving end. For a two-lens link, the second lens focuses the signal into a much smaller diffraction pattern; however, for optical wavelengths and metre-scale receiving apertures this fine structure is aperture-averaged, and the averaged additional gain becomes independent of the second lens mass. We estimate photon rates and shot-noise-limited SNRs for these idealized configurations. The results indicate that gravitational lensing can in principle support high-SNR interstellar optical power links, subject to stringent alignment, finite-aperture, transmitter-beam, and coronal-background assumptions.

gr-qc↗

arXiv2026

Direct High-Resolution Imaging of Earth-like Exoplanets with the Solar Gravitational Lens

We present a scalar, aperture-averaged observability benchmark for resolved exoplanet imaging with the solar gravitational lens (SGL). A real Earth luminance map is propagated through a scanned SGL image plane using source-to-image-plane compression, a finite-aperture SGL kernel, and an Einstein-ring photon-count model. We inject photon noise, finite-exposure smear, cloud-like temporal variability, coronal and detector-calibration residuals, optical-operator mismatch, and navigation error, then reconstruct with a regularized Fourier/Wiener inverse. For an Earth-radius planet at 30 pc observed from 650 AU with a 1 m telescope, the projected image cylinder is 1.338 km across; a $128\times128$ raster has 10.46 m image-plane pitch, 99.55 km source pixels, and convolved-image SNR 43.16 for 1800 s per sample. With the stated ring-extraction, temporal, background, calibration, and navigation mitigations, the fiducial reconstruction reaches SNR 6.89, structural similarity 0.848, normalized RMS error 0.439, and a 232 km Fourier-ring-correlation resolution proxy. A higher-count case reaches SNR 10.49, structural similarity 0.927, normalized RMS error 0.287, and the 199 km two-pixel grid floor. Controlled cloud tests show that a static inverse fails for rotating cloudy data, whereas phase-registered robust coadds recover persistent surface-proxy structure in the scalar model. The dominant requirements are temporal sampling, coronal and detector calibration, ring extraction, image-plane metrology, optical-operator knowledge, and dynamic inversion, not calibrated monopole SGL blur. The benchmark demonstrates recoverable 200-230 km-class broadband spatial contrast in the stated scalar model, but does not validate propulsion, communications, coronagraphic or external-occulter propagation, physical solar multipoles, physical cloud fields, or a full dynamic retrieval pipeline.

astro-ph.IM↗

arXiv2026

Late-Transition Interacting Thawer Dark Energy: Model Definition and Benchmark Consistency Tests

We formulate the late-transition interacting thawer (LTIT) as a late-activating, variable-coupling realization of coupled quintessence in which a canonical scalar field couples conformally only to cold dark matter. The construction is a non-universal dark-sector interaction: baryons and radiation remain minimally coupled, while CDM follows a conformally related metric. This structure ties three observational sectors to one microscopic mechanism--the pre-recombination calibration scale, the low-redshift expansion history, and the coupled growth response. We derive the exact background equations, the exact CDM scaling identity $\rhoc(a)=ρ_{c0}a^{-3}C[ϕ(a)]/C(ϕ_0)$, and the coupled CDM--scalar perturbation equations in synchronous gauge in a form suitable for Einstein--Boltzmann solvers. In the representative benchmarks, $Ω_ϕ(z_*)\sim10^{-9}$, $|Δr_d/r_d|\le3.82\times10^{-3}$, and $\max_{0<z<3}|E/E_{Λ\mathrm{CDM}}-1|\le0.380\%$, while the quasi-static growth indicator ranges from $0.725\%$ to $5.94\%$. LTIT therefore demonstrates how late activation can preserve the early calibration sector while producing a perturbation-sensitive signature, providing a concrete target for Boltzmann-level tests of interacting dark energy.

gr-qc↗

arXiv2026

High-Precision Relativistic Time Scales for Mars Surface and Orbital Clocks

We develop a Mars-centered post-Newtonian framework for relating barycentric coordinate time, Mars-centered coordinate time, a conventional Mars surface time scale, and the proper times of landed and orbiting clocks. The construction follows the International Astronomical Union BCRS/TCB formalism, introduces Areocentric Coordinate Time (TCA), and writes each clock transformation as a secular rate plus zero-mean periodic terms. Terms are retained when their fractional-frequency amplitude exceeds 5e-18 or their one-way accumulated timing amplitude exceeds 0.1 ps. The numerical realization uses the GMM-3 Mars gravity field through degree and order 120, point-mass tides from the Sun, Phobos, and Deimos with origin and dipole terms removed, and bounds on omitted local c^-4 and external-perturber terms. Representative low-Mars-orbit, areostationary, Phobos-/Deimos-distance, and highly elliptical relay regimes are evaluated. Relative to the adopted Mars surface scale, a 300 km near-polar clock is slower by 4.56 microseconds per day, while areostationary and Deimos-distance clocks are faster by 9.13 and 9.52 microseconds per day. The leading Mars-J2 timing line is about 87 ps at 300 km altitude and remains several ps near areostationary radius for inclined or librating areosynchronous cases; perihelion-scaled solar tides become retained sub-ps terms in high relay orbits. The result is a reference-system and model-retention framework, not a final operational Mars Time Ephemeris. A realized sub-ps system still requires a selected planetary ephemeris, Mars orientation and seasonal-gravity model, spacecraft orbit determination, calibrated link delays, and covariance analysis. Time-variable low-degree gravity from seasonal CO2 exchange is a leading surface-realization term and must be modeled, monitored, or empirically bounded before sub-ps Mars surface-scale claims are made.

gr-qc↗

arXiv2026

Quantitative Nonequilibrium Pathway from Fundamental Physics to the Emergence and Persistence of Exoplanetary Biospheres

We present a physics-based framework that runs from fundamental interactions and constants to biospheres, using a sequence of quantitative nonequilibrium thresholds ("gates"). Each gate is an inequality in measurable variables-free-energy flux, reaction-transport rates, replication fidelity, coding capacity, ecological closure, and climate feedback gains. Crucially, the gate vector is anchored in fundamental physics: dimensionless constants, nuclear resonance placements (e.g., the $^{12}$C Hoyle state), statistical mechanics (Landauer's bound $k_BT \ln 2$) fix the energetic, kinetic, information-theoretic margins that propagate through the gates. This anchoring lets us propagate sensitivities of the constants into biosphere-level metrics (net primary productivity (NPP), cycle-closure ratios, and climate feedback gain), yielding an end-to-end map from constants to biospheres. The framework is predictive: it yields testable inequalities, margin rankings, and population-level correlations between stellar and planetary boundary conditions and biosphere feasibility. It does not claim point predictions of life prevalence; rather, it specifies which gate margins are observable-bounded versus prior-dominated under explicitly stated chemistry/solvent families and forward models. Darwinian dynamics (heritable variation under selection) appears mid-pipeline; the end of the pipeline is a planet-scale biosphere capable of sustaining positive NPP, closing elemental cycles over geologic time. Questions of prevalence are secondary; our primary objective is to establish a constructive physics->chemistry->biology->genetics->ecosystems pipeline with testable margins and observables. As a result, we recast abiogenesis and biosphere persistence as a gate vector of falsifiable inequalities and map their margins to exoplanet observables, turning the problem into a phase diagram with explicit, testable slack.

physics.gen-ph↗

arXiv2026

Propulsion Trades for a 2035-2040 Solar Gravitational Lens Mission

The Solar Gravitational Lens (SGL) enables resolved imaging and spectroscopy of nearby terrestrial exoplanets, but useful science begins only after a spacecraft reaches roughly 650-900 astronomical units (AU). A 20 yr lower-bound trip to 650 AU requires an average radial speed of 32.5 AU per year, or 154 km/s, before launch, targeting, steering, and operations margins. We compare close-perihelion solar sailing, fission-electric nuclear electric propulsion (NEP), and high-thrust Oberth injection followed by NEP cruise using common lower-bound outbound-leg architecture envelopes, not closed end-to-end trajectories. For an ideal sail passing 0.05 AU from the Sun, total sailcraft areal density must be about 4.9 grams per square meter to reach 105 km/s, and 2.3 grams per square meter to reach 155 km/s. Thus sub-20 yr sail-only access requires ultra-low areal density plus deep-perihelion thermal qualification. For a 20 t NEP spacecraft with 800 kg payload and Isp=9000 s, optimized constant-power transfers reach 650 AU in t_rep ~ 27-33 yr when the integrated power-plus-propulsion specific mass is 10-20 kg per electric kilowatt, requiring 0.18-0.30 megawatt-electric (MWe) and few-newton thrust. NEP-only t_rep <20 yr requires <3 kg per electric kilowatt, while hybrid architectures can approach t_rep ~ 20 yr if an upstream injection stage supplies 50-70 km/s. Thus sail-first is the nearer-term lightweight-access path; hybrid injection+NEP is higher-capability but requires prior high-energy-injection and 0.2-0.4 MWe integrated NEP demonstrations.

astro-ph.EP↗

arXiv2026

Orbital Debris in Earth Orbit: Operations, Stability, Control, and Market Formation

Orbital debris is a nonlinear control problem in a stratified orbital environment, not a static inventory. This paper develops a reduced-order shell-and-size framework that connects collision-rate scaling, fragment-production gain, natural and controlled sinks, and orbital residence time to intervention ranking and procurement design. The formulation identifies three dominant control levers for near-term orbital sustainability: high-confidence disposal and short post-failure residence time for new spacecraft; reduced encounter-plane covariance for the high-risk conjunction tail; and retirement or deflection of the residual hazard stock of long-lived inactive bodies. A source-gain/sink stability margin separates shells that are operationally crowded but dynamically damped from shells that are dynamically amplifying. The analysis distinguishes the traffic-driven workload peak near 500--600 km from the persistence-driven hazard peak near $\sim$850 km, where inactive mass and long lifetime dominate future fragment production. Current public statistics report $\sim$44,870 tracked objects and more than 16,200 tonnes of material in Earth orbit, with model populations far larger below routine-catalog thresholds. The resulting intervention stack is rapid post-mission disposal, targeted covariance improvement for high-risk encounters, selective just-in-time collision avoidance or active removal of high-hazard derelicts. The appropriate procurement metric is not the number of objects removed, but verified reduction in time-integrated environmental hazard: verified disposal, verified reduction in ambiguous high-risk conjunctions, verified reduction in residual hazard stock.

astro-ph.IM↗

arXiv2026

High-Precision Amplitude-Modulated Continuous-Wave Lunar Laser Ranging

Lunar laser ranging (LLR) currently delivers mm-class tests of relativistic gravity and the lunar interior, but further gains are limited by photon-starved pulsed systems, array-induced pulse broadening, and atmospheric variability. This paper develops the metrology and covariance layer for high-power amplitude-modulated continuous-wave (AM-CW) LLR. The optical link budget and kW-class CW architecture are taken from the companion high-power CW LLR analysis; here the focus is on RF-envelope phase observables, multi-tone ambiguity removal, range and range-rate estimators, detector requirements, Doppler derotation, and observation-level covariances. For a GHz-class precision tone, $c/(4πf_m)$ =2.38567 cm/rad, so 0.10 mm photon-limited range precision requires SNR ~ 240. With detected photon rates appropriate to a 1 kW, 1064 nm transmitter on a 1-2 m class telescope ranging to 10 cm corner-cube retroreflectors, the T ~ 100 s photon-statistical range floor is 0.08-0.14 mm in a generic high-power case, 30-60 um in a dedicated AM-CW case, and <30 um in a photon-rich case. With representative residual atmosphere and instrument allocations, a dedicated station can plausibly reach 0.08 mm absolute range precision under favorable conditions. Range-rate precision below 1 um/s requires several-hundred-second windows, or shorter windows only in photon-rich operation. Differential LLR between nearby lunar reflectors suppresses common-mode station and atmospheric terms, but it cannot suppress independent photon noise. Robust design bands are ~45-90 um for the dedicated AM-CW case and ~35-60 um in photon-rich excellent-seeing operation. The resulting requirements on link SNR, Doppler derotation, detector mode, instrument PSD/Allan stability, oscillator slew, multi-tone nonlinearity, and differential CONOPS are presented.

astro-ph.IM↗

arXiv2026

Orbital Data Centers: Spacecraft Constraints and Economic Viability

Orbital data centers are being evaluated as solar-powered compute constellations and relay-integrated processing platforms. Their feasibility is not set by orbital solar flux alone, but by simultaneous closure of photovoltaic generation, eclipse recharge, radiative heat rejection, sustained space-to-ground communications, utilization, replacement cadence, and delivered compute-years over finite mission life. This paper derives necessary cluster-level competitiveness conditions using delivered information-technology (IT) electrical power $P_{\rm IT}$, deployed mass per delivered IT power $m_{\rm kW}$ in kg/kW, communication intensity $Γ=D_{\rm sg}/E_{\rm IT}$, sustained communication ceiling $Γ_{\max}$, effective utilization $U_{\rm eff}$, and lifetime penalty $Π_{\rm life}$. For a representative $P_{\rm IT}$=1 MW high-sunlight anchor, the base case gives beginning-of-life photovoltaic area $A^{\rm BOL}_{\rm PV}=5.64 \times 10^3 {\rm m}^2$, radiator area $A_{\rm rad}=2.50 \times 10^3 {\rm m^2}$, and 29.4 kg/kW for photovoltaic, storage, and radiator mass; fixed spacecraft mass raises the total to 34-59 kg/kW. At m_kW ~ 40 kg/kW, a terrestrial infrastructure benchmark of 10-40 k\$/kW allows only 250-1000 \$/kg for the combined launch and spacecraft-build cost before space-to-ground communications, operations, utilization, and lifetime terms are included. That allowance is 3.4-13.5 times below the current public Falcon 9 dedicated low-Earth-orbit launch-price benchmark alone, before spacecraft build is included. Space-native preprocessing and communications-integrated edge compute are credible early regimes; terrestrial-user general compute closes only for low Earth-coupled communication intensity, high effective utilization, long delivered lifetime, and very low combined launch-plus-build cost.

physics.gen-ph↗