Study Guide — Low Earth Orbit (LEO) Satellite Systems

Unit Overview

Low Earth Orbit is where the satellite industry has been reborn. Once the domain of a handful of science missions and one telephone constellation (Iridium), LEO now hosts mega-constellations delivering broadband to entire continents, Earth-observation fleets imaging the whole planet daily, and the International Space Station. LEO systems trade the simplicity of geostationary satellites for a radically better link budget, millisecond latency, and enormous frequency-reuse capacity — paid for in constellation complexity: dozens to thousands of satellites, minutes-long passes, handovers, and serious debris responsibility. This guide builds the engineering layer beneath the headlines.

Learning Outcomes

After studying this unit and completing the tutorials you should be able to:

Compute LEO orbital parameters (period, velocity) and explain drag and decay.
Size coverage footprints with elevation masks and derive constellation minima.
Design Walker constellations and explain inclination choices (equatorial vs polar).
Build LEO downlink budgets including Doppler, pointing, and rain effects.
Explain inter-satellite links and bent-pipe versus regenerative routing.
Quantify handover frequency and network latency for LEO constellations.
Describe LEO spacecraft bus trends (flat-panel platforms, phased arrays, electric propulsion).
Evaluate debris-mitigation and spectrum/orbital-slot policy constraints.

Indicative Study Time

Activity	Time
Guided reading (Sections 1–8)	5 hours
Figures studied / examples reworked	2 hours
Tutorial problems (Section 9)	3 hours
Revision of key equations & glossary	1 hour

Prerequisite knowledge: Kepler's third law, vis-viva equation, free-space path loss, link budgets (EIRP, G/T, C/N₀), the coverage geometry of Section 1 of the companion guide "LEO, MEO, GEO and HEO Satellite Systems".

Section 1 — LEO Fundamentals

1.1 The Numbers That Define LEO

T = 2π√(a³/μ), v = √(μ/r), μ = 3.986×10⁵ km³/s²

Altitude	Period	Velocity	Example
~200 km (lowest practical)	~88.5 min	~7.8 km/s	Imaging sats (short campaigns)
420 km	~92.8 min	~7.7 km/s	ISS (continuous re-boost)
550 km	~95.6 min	~7.6 km/s	Starlink shells
780 km	~100.4 min	~7.45 km/s	Iridium
1 200–1 400 km	~109–114 min	~7.2 km/s	OneWeb, older EO sats
2 000 km (LEO ceiling)	~127 min	~7.0 km/s	—

1.2 Why Not Lower or Higher?

Below ~300 km: drag is severe (ISS at 420 km still loses ~2 km/month without re-boost); lifetime measured in weeks–months; station-keeping propellant dominates.
300–600 km: the sweet spot for broadband constellations — manageable drag, passive decay within 5–25 years (debris-compliant), lowest path loss.
700–1 500 km: better coverage per satellite and slower drag, but debris persists 100+ years to effectively forever (Fig. C); OneWeb's ~1 200 km choice reflects coverage/lifetime trade-offs debated hotly by regulators.

1.3 Pass Geometry: The Defining LEO Experience

A satellite at 550 km rises above a 25° elevation mask, crosses the sky in about 4–6 minutes, and sets. Every user is handed over to the next satellite roughly every minute or two. This single geometric fact drives LEO network architecture: fast beam steering, frequent inter-satellite routing updates, and user terminals that can track or electronically steer.

Check Your Understanding 1

Compute the period and velocity at 1 200 km (OneWeb).
Why does a LEO satellite's apparent motion across the sky reverse direction between ascending and descending passes?

Answers

a = 7 571 km → T = 2π√(7571³/3.986×10⁵) ≈ 6 562 s ≈ 109.4 min; v = √(μ/a) ≈ 7.25 km/s.
Orbit direction is fixed in inertial space while Earth rotates beneath: on the ascending pass the satellite travels eastward across the sky; after passing overhead, its ground track heads southeast (for prograde orbits) — the geometry of viewing a moving object from a rotating frame.

Section 2 — The LEO Orbital Environment

2.1 Atmospheric Drag

a_drag ≈ −½ ρ v² (C_dA/m) — proportional to atmospheric density ρ, which grows exponentially as altitude decreases

Drag removes energy → orbit decays; below ~400 km decay is fast enough that dead satellites self-clean in years — the 25-year (now increasingly 5-year) debris rule is trivially met.
Living satellites must re-boost: ISS uses resupply vehicle thrusters; Starlink sats carry Hall thrusters for both station-keeping and active de-orbit.
Drag varies with solar activity: a 550 km satellite decaying in 12 quiet-Sun years might decay in 5 active-Sun years.

2.2 The Debris Problem

Fig. C — Post-mission lifetime of an uncontrolled satellite vs altitude (schematic). The broadband industry has converged on 550 km precisely because nature provides free disposal there; altitudes above ~700 km are effectively permanent landfills.

Kessler syndrome: collisions fragment debris; fragments collide further — a runaway cascade that could deny LEO for centuries. Mitigation: passivation (venting batteries/fuel), 25-year (FCC: 5-year) disposal rule, conjunction screening, and mega-constellation "fail-safe" low orbits.
Conjunction management: constellations autonomously maneuver thousands of times per year; each maneuver trades propellant (lifetime) against collision risk.

2.3 Radiation and Thermal

Van Allen belts avoided: LEO sits below the inner belt — total dose is moderate; COTS (commercial off-the-shelf) electronics with modest shielding are feasible at 550 km — a key cost enabler.
South Atlantic Anomaly: the belt dips over the South Atlantic; single-event upsets cluster there — software must scrub memory.
Thermal cycling: ~30 minutes sunlit, ~30 minutes eclipsed each orbit; flat-panel satellites radiate one face to space — a major bus-design constraint.

Check Your Understanding 2

Why is 550 km called "fail-safe" for mega-constellations?
A dead satellite at 900 km: estimate its persistence using Fig. C and argue for or against a regulator allowing new deployments there.

Answers

A failed satellite at 550 km decays naturally in roughly 5–20 years with no propulsion — collision exposure is bounded; at 1 200 km the same failure persists centuries, so reliability must be engineered, not inherited from physics.
Fig. C: ~500 years. Argument against: each failed object is a centuries-long collision seed; argument for: with active de-orbit capability and very high reliability, the orbit is usable. Modern policy leans toward requiring active disposal regardless of altitude.

Section 3 — LEO Constellation Design

3.1 Coverage with Elevation Masks

ρ = arccos( (R_E/(R_E+h)) · cos ε_min ) − ε_min

where ε_min is the minimum elevation angle. Terrain, buildings, rain, and interference set ε_min = 5–10° for professional terminals and ~25° for consumer broadband.

Fig. A — Coverage half-angle vs altitude for three elevation masks. At 550 km with a 25° mask the half-angle is only ~8.5° — each satellite serves a footprint of radius ≈ 950 km; a 10° mask gives ~15° (≈1 700 km radius).

Example 3.1 — Starlink-style arithmetic. At 550 km, ε_min = 25°: cos ρ = (6371/6921)·cos25° = 0.9205 × 0.9063 = 0.8343 → ρ = 33.47°… then subtract the mask: ρ_service = 33.47° − 25° = 8.5°. Equatorial ring minimum: 360°/(2×8.5°) ≈ 21 satellites — and real shells are inclined, so several interleaved rings cover mid-latitudes and polar coverage needs near-polar planes. Capacity (not geometry) then multiplies the count by 10–100×.

3.2 Walker Constellations

Walker notation: (i : T/P/F) — T satellites in P planes, all at inclination i, phased by F

Idealized single-fold coverage: N_min ≈ 4.84 / sin²(ρ) (continuous single coverage, optimized Walker) — the classic L. Rider result; e.g. ρ = 10° → N_min ≈ 160 satellites for single-fold coverage; multi-fold (capacity) scales with the fold count.
Polar planes (i ≈ 90°): cover poles; adjacent planes' satellites counter-rotate at seam → special phasing; Iridium's 6-plane polar + ISL mesh.
Inclined shells (i ≈ 53° for Starlink): concentrate capacity where the population is (30–60° latitude); the seam problem disappears; polar coverage sacrificed (acceptable for commercial broadband, not for GNSS-like global mandates).

3.3 Capacity Through Frequency Reuse

Each satellite's footprint splits into cells (beams); the same spectrum is reused in non-adjacent cells — exactly the cellular principle at orbital scale. Smaller cells (lower altitude, narrower beams) → more reuse → more total capacity. This is why Starlink's thousands of satellites make economic sense: aggregate capacity scales with satellite count.

Check Your Understanding 3

Using Fig. A, find the service half-angle and ring minimum at 780 km with a 10° mask.
Why do broadband constellations choose i ≈ 53° rather than 90°, while Iridium chose polar?

Answers

ρ ≈ 14.5° → ring ≈ 360/29 ≈ 12.4 → 13 satellites per ring.
i = 53° maximizes dwell over populated mid-latitudes and avoids the polar-seam phasing problem; Iridium's mission demanded pole-to-pole coverage (aviation/military/maritime), which only polar planes deliver.

Section 4 — LEO Link Engineering

4.1 The Link Budget

C/N₀ = EIRP + (G/T)_rx − L_FS − L_atm − L_point − L_misc + 228.6 (dBHz)

L_FS = 92.45 + 20 log f(GHz) + 20 log d(km)

Example 4.1 — Starlink-class downlink at 11 GHz. d = 550 km: L_FS = 92.45 + 20.8 + 54.8 ≈ 168 dB (vs GEO at same frequency ≈ 205 dB — a 37 dB advantage). With satellite EIRP ≈ 40–45 dBW per beam, user-terminal G/T ≈ 10 dB/K and misc losses 3 dB: C/N₀ ≈ 45 + 10 − 168 − 3 + 228.6 ≈ 113 dBHz; in 250 MHz: C/N ≈ 113 − 84 = 29 dB — ample for high-order modems, exactly why pizza-box terminals work.

4.2 Doppler: The Signature LEO Impairment

f_d = (v_radial/c) f₀ → at L-band: up to ±40 kHz; at Ku-band: ±300 kHz

Fig. B — Simulated overhead pass at 550 km, 1.6 GHz: elevation (dashed) rises and falls in ~8 minutes; Doppler (solid) swings through zero at closest approach at a rate of several kHz per second. Receivers must acquire fast and hand over mid-pass.

Time-varying Doppler demands pre-compensation (the satellite knows its ephemeris) or wide capture-range demodulators.
Doppler-based positioning is a bonus: LEO Doppler curves rival GNSS for opportunistic navigation.

4.3 Rain, Pointing, and Other Losses

Rain fade at Ka-band: 10–15 dB fades in heavy rain — mitigated by gateway diversity (many gateways, route around storms), adaptive coding, and the downlink's large clear-weather margin.
Pointing loss: electronically steered phased arrays scan to 60°+ off-boresight with ~2–4 dB scan loss — designed into G/T budgets.
Atmospheric absorption: minimal at Ku; oxygen/water lines matter above ~20 GHz — feeds the choice of Ku/Ka bands for broadband and L/S for MSS/IoT.

Check Your Understanding 4

Compute FSPL and C/N₀ for a 2 GHz LEO IoT downlink (satellite EIRP 25 dBW, terminal G/T = −15 dB/K, misc 2 dB).
Why is the user-terminal G/T negative in the IoT case yet the link still closes?

Answers

L_FS = 92.45 + 6 + 20log(550) = 92.45 + 6 + 54.8 = 153.3 dB; C/N₀ = 25 − 15 − 153.3 − 2 + 228.6 = 83.3 dBHz.
The −15 dB/K reflects a tiny antenna and noisy consumer receiver, but the low FSPL and modest bandwidth need (narrowband IoT: 10 kHz → required C/N₀ ≈ 40 + 83 = … C/N = 83.3 − 40 = 43 dB) leave enormous margin.

Section 5 — LEO Spacecraft Bus and Payload Trends

5.1 The Flat-Platform Revolution

Mega-constellation satellites are mass-produced consumer electronics in space: a flat rectangular bus (solar array as one face, antennas on the other) with:

Phased-array antennas: hundreds/thousands of elements steer thousands of beams electronically — no moving parts, beams re-pointed in microseconds for handover.
Hall-effect (electric) propulsion: xenon/krypton thrusters: ΔV modest but propellant-efficient — sufficient for station-keeping, collision avoidance, and de-orbit at 550 km.
Autonomous operations: constellation-wide collision screening, orbit-raising, and de-orbit without human-in-the-loop for routine events.

5.2 Inter-Satellite Links (ISLs)

Type	Pros	Cons	Used by
RF (Ka-band)	Mature, all-weather	Lower data rate per aperture	Iridium (historically), some LEOs
Optical (laser)	Tb/s-class, narrow beams = low interference, small apertures	Cloud-avoidance for space-to-ground; precise pointing	Starlink, Telesat LEO plans

ISLs convert a constellation into an orbital mesh: traffic crosses oceans in space, lands at the nearest gateway — cutting latency and gateway-count requirements.

5.3 Mass, Cost, and Production

Starlink v1.5: ~295 kg, produced at thousands per year — prices approaching consumer-electronics curves; launch cost ≈ $1–2k/kg on rideshare/reusable boosters.
Lifetime design ~5 years at 550 km: satellites are consumables — design for cheap replacement rather than 15-year longevity.

Check Your Understanding 5

Why does the flat-panel form factor matter economically (two reasons)?
When do RF ISLs beat optical?

Answers

(1) Stacking density: dozens per launch fairing → lowest $/kg to orbit; (2) mass production: one flat face is a single phased array — panel-level assembly lines replace bespoke satellite integration.
When pointing precision is limited, weather-hardness is paramount, or data rates are modest — RF tolerates misalignment and needs no cloud-avoidance strategy.

Section 6 — Handover and Network Architecture

6.1 The Handover Problem

Intra-plane: next satellite in the same orbital plane replaces the setting one — predictable, minutes apart.
Inter-plane: crossing into an adjacent plane's footprint — less frequent but at shell seams (polar) it is continuous and capacity-critical.
Beam-level handover in phased-array systems is effectively instantaneous; the challenge is routing and state management at constellation scale (thousands of moving routers).

6.2 Latency Budget: The LEO Selling Point

Segment	Typical value
User → satellite (up)	~2 ms
In-space hops (2–4 ISLs, ~2 000 km each)	~10–30 ms incl. processing
Down to gateway + terrestrial	~10–30 ms
Total RTT (LEO, routed)	~25–45 ms
GEO RTT (comparison)	~500–600 ms incl. terrestrial tail

Fiber comparison: light in glass travels ~⅔ c, so LEO's vacuum path can actually beat fiber on long east–west routes (e.g., London–Johannesburg–Singapore paths). "Lower latency than fiber" is a real, engineering-defensible claim on specific routes.

Check Your Understanding 6

Why does a LEO constellation still need ground gateways at all (two reasons)?
Estimate the minimum possible one-way delay for a 2 000 km ISL chain plus two 550 km user/gateway legs.

Answers

(1) Spectrum licensing: gateways tie traffic to licensed territories; (2) content/peering: the internet lives on terrestrial fiber — every session must land somewhere.
Path ≈ 2×550 + 2 000 ≈ 3 100 km → 3 100/3×10⁵ ≈ 10.3 ms propagation alone (plus processing).

Section 7 — Case Studies

Fig. D — Operational/planned constellation sizes span two orders of magnitude: the design space runs from "a telecom operator's fleet" (Iridium, 66) to "an internet platform" (Starlink, thousands).

System	Orbit	Architecture	Key engineering lesson
Iridium (NEXT)	780 km, i = 86.4°, 66 sats, 6 polar planes	Cross-linked mesh, L/S MSS, bent-pipe + intersatellite routing	Full global coverage incl. poles; the seam problem solved by ISLs; the original proof that LEO constellations are viable
Starlink	~550 km shells, i = 53°/70°/97.6° (multi-shell)	Ku/Ka bent-pipe + optical ISL mesh	Mass production + short-life consumable sats + gateway diversity; capacity as the economic driver
OneWeb	1 200 km, i = 87.9°	Ka bent-pipe, no ISLs (first gen)	Interchangeable sats, "pop-in/pop-out" slot replacement; polar orbits for global enterprise/government reach
Planet Labs (EO)	~475–525 km SSO	Dove cubesat fleet, ~150+ imaging sats	Temporal resolution as the product: whole-Earth daily imaging via many cheap sats
Iridium vs Globalstar	—	Mesh vs bent-pipe	History lesson: Globalstar (bent-pipe, 48 sats) went bankrupt in the 2000s; Iridium's ISL architecture survived — constellation economics are unforgiving

Section 8 — LEO System Trade-offs

Decision	Lower altitude (~450–550 km)	Higher LEO (~1 000–1 400 km)
Path loss / terminal size	Best — small user terminals	+5–7 dB FSPL — bigger terminals or beams
Coverage per satellite	Small footprint → more sats	~2–3× footprint → fewer sats
Drag & propellant	Significant; de-orbit easy	Minor; de-orbit needs propulsion
Debris compliance	Passive decay < 25 yr (often < 10)	Active disposal mandatory; centuries if failed
Latency	Identical (ms-scale)	Identical
Lifetime / replacement	~5 yr consumables	~7–10 yr — but failure persistence is the risk

The regulatory lens: national regulators (FCC) and the ITU now impose disposal timelines, spectrum coordination (Ku/Ka filings with "bring-into-use" deadlines), brightness/astronomy mitigation, and conjunction-reporting duties. A modern LEO system is licensed as critical infrastructure, not merely launched.

Section 9 — Tutorial Problems

Constants: μ = 3.986×10⁵ km³/s², R_E = 6 371 km, c = 3×10⁵ km/s, FSPL = 92.45 + 20log f(GHz) + 20log d(km).

Compute period, velocity, and orbital angular rate (rad/s) at 550 km.
Derive the service half-angle formula ρ = arccos((R_E/(R_E+h))cos ε) − ε from a geometry sketch. Then compute ρ and the equatorial-ring minimum at 550 km for ε = 5°, 15°, 25°.
A single-fold continuous-coverage Walker constellation at 550 km uses ε = 10°. Estimate N_min via N ≈ 4.84/sin²ρ and comment on why real broadband constellations exceed this by an order of magnitude.
Build a full downlink budget at 14 GHz (Ku): satellite EIRP 42 dBW, slant 1 000 km, user G/T 8 dB/K, pointing 1.5 dB, rain 6 dB, misc 2 dB. Find C/N₀ and C/N in 100 MHz; comment on modem choice.
Maximum Doppler at 14 GHz for a 550 km pass — what does this imply for demodulator design?
ISL latency: a route crosses 6 optical ISLs of 2 000 km each plus two 550 km ground legs. Compute propagation time and compare with a GEO hop (35 786 km up + down).
A constellation must guarantee single-fold coverage at ε = 25° from 550 km. Using ρ = 8.5°, estimate the ring minimum per shell and discuss why inclined shells at 53° need more rings than the equatorial estimate suggests.
Drag: atmospheric density at 420 km is ~1.5×10⁻¹² kg/m³. For a satellite with C_dA/m = 0.01 m²/kg and v = 7.66 km/s, compute the deceleration. Roughly how long to decay from 420 km if density is treated as constant (hint: Δv per orbit vs orbital energy)? Identify why this crude model breaks down.
Compare (tabular, 6 rows) a 66-satellite polar LEO MSS constellation against a 3-GEO FSS system for: coverage, latency, terminal size, handover, gateway count, and cost structure.
Mission design: Kenya's government wants (a) nationwide broadband to schools, (b) wildlife IoT tracking across the Mara, (c) disaster-response comms immune to fiber cuts. For each, choose LEO (broadband constellation), LEO-IoT, or GEO back-up — defend in ≤3 lines each.

Selected solutions

a = 6 921 km; T = 2π√(6921³/μ) ≈ 5 736 s ≈ 95.6 min; v = √(μ/a) ≈ 7.59 km/s; n = √(μ/a³) ≈ 1.08×10⁻³ rad/s.
Geometry: horizon ray from ground tangent... standard result: cos(ρ+ε) = (R_E/(R_E+h)) cos ε. ε=5°: ρ = arccos(0.9205×0.9962)−5 = arccos(0.9170)−5 = 23.45−5 = 18.4° → ring 360/36.9 ≈ 9.7 → 10. ε=15°: arccos(0.9205×0.9659)−15 = arccos(0.8891)−15 = 27.26−15 = 12.3° → 15 sats. ε=25°: 8.5° → 22 sats.
ρ(10°) ≈ 15° → N ≈ 4.84/sin²15° ≈ 4.84/0.067 ≈ 72 sats for single-fold. Broadband needs 10–100× capacity folds (many simultaneous beams per cell), so hundreds–thousands of sats are a capacity decision, not a coverage decision.
L_FS = 92.45 + 22.9 + 60 = 175.4 dB. C/N₀ = 42 + 8 − 175.4 − 1.5 − 6 − 2 + 228.6 = 93.7 dBHz; C/N in 100 MHz = 93.7 − 80 = 13.7 dB — supports QPSK/8-PSK with coding in rain; 16-APSK needs ~4 dB more (link adaptation handles the fade).
Δf = (v/c)f₀ = (7.6/3×10⁵)×14×10⁹ ≈ ±355 kHz — demodulators need ±400 kHz capture with fast acquisition; Doppler rate ≈ several kHz/s mid-pass.
Path = 6×2 000 + 2×550 = 13 100 km → 13 100 / 3×10⁵ km/s = 0.0437 s ≈ 44 ms. GEO comparison: 2×35 786 / 3×10⁵ ≈ 0.24 s ≈ 239 ms. The LEO in-space route is ~5.5× faster — before counting the terrestrial tail, where fiber's ⅔-c further penalizes GEO routes.
Ring ≈ 22 sats at 53° inclination: to cover a latitude band φ with ring planes inclined at i, effective coverage swaths shrink with latitude (footprint projected); typical designs use 24–72 sats per shell ring of planes — hence Starlink's many rings. Equatorial estimates are a lower bound only.
a = ½ × 1.5×10⁻¹² × (7.66×10³)² × 0.01 ≈ 4.4×10⁻⁴ m/s². Energy reasoning: E_orb = −μ/2a → dE/E = da/a; per-orbit Δa from drag… crude estimate: Δv × v / (μ/a) — order 0.1–1 km per day decay at 420 km. Breaks down because ρ varies exponentially with altitude and solar cycle, and v·Δv approach ignores the altitude-dependence feedback (decay accelerates).
Table: LEO MSS — global incl. poles, ~50–90 ms RTT, small handhelds, frequent handover, few gateways with ISLs, high capex/many cheap sats; GEO FSS — continental (not poles), ~500+ ms RTT, 0.6–3 m dishes, no handover, many gateways possible, few expensive sats.
(a) LEO broadband — capacity and latency suit classrooms; (b) LEO-IoT (e.g., cubesat/LoRa-style store-forward or commercial IoT sats) — low data rate, low power trackers, vast coverage; (c) GEO backup terminal at each county HQ — fixed, always-on, independent of LEO congestion.

Section 10 — Glossary of Key Terms

Bent-pipe: Transponder that receives and re-transmits without onboard processing; simplest LEO payload.
Conjunction: A predicted close approach between satellites or debris; triggers screening and possible maneuver.
Coverage fold: Number of satellites simultaneously covering a point; capacity scales with fold.
Elevation mask (ε_min): Lowest elevation angle at which service is provided; sets footprint size and constellation count.
Hall thruster: Electric propulsion: ionizes xenon/krypton and accelerates it electrostatically/magnetically; efficient ΔV for LEO sats.
Inter-satellite link (ISL): RF or optical cross-link connecting constellation satellites into a mesh.
Kessler syndrome: Runaway debris cascade from cascading collisions; the central debris-policy fear.
Phased array: Electronically steerable antenna: beam direction set by element phase, enabling microsecond handovers.
Shell: A set of orbital planes at common altitude and inclination within a constellation.
South Atlantic Anomaly (SAA): Dip in the Van Allen belts over the South Atlantic causing elevated single-event upsets.
Walker constellation: Symmetric constellation notation (i : T/P/F); basis of most modern LEO designs.

Section 11 — References and Further Reading

T. Pratt, J. Bostian & J. Allnutt, Satellite Communications, 2nd ed., Wiley, 2003 — link budgets and constellation geometry.
D. Roddy, Satellite Communications, 4th ed., McGraw-Hill, 2006.
J. R. Wertz & W. J. Larson (eds.), Space Mission Analysis and Design, 3rd ed., Microcosm Press, 1999 — constellation design and coverage math.
M. Richharia, Mobile Satellite Communications: Principles and Trends, Wiley, 2014 — MSS constellations and handover.
FCC/ITU filings and debris-mitigation orders (e.g., FCC 5-year disposal rule, 2022) — the regulatory layer of modern LEO design.

Exam guidance: LEO questions are won by showing the geometry first (draw the Earth, the mask angle, the footprint), then the formula, then the numbers. Quote ρ before any constellation count, and always state the elevation mask — without it, your satellite count is meaningless.