ALOUETTE 2
Country: Canada
Live Position
Ground Track · Last 90 Minutes
Upcoming Passes · Over Your Location
About This Satellite
Alouette 2 launched on November 29, 1965 together with Explorer 31. It continued the Canadian investigation of the topside ionosphere begun by Alouette 1, combining a radio sounder with additional measurements of the space environment. The two spacecraft shared a launch, but they remained separate experimental platforms with distinct catalog identities.
The payload investigated more than radio echoes
NASA's historical inventory lists the topside sounder, radio-noise and very-low-frequency receivers, energetic-particle detectors, and an electrostatic probe. These instruments did not all measure the same thing. Their combination connected the behaviour of radio propagation with properties of the plasma and particles around the spacecraft.
Local measurements and remote sounding are complementary
A probe samples its immediate environment, whereas a sounder uses transmitted signals and returned echoes to investigate a region away from the spacecraft. The distinction helps explain why several instruments were useful on a single ionospheric mission. A position estimate locates the platform but cannot supply either the probe measurements or the echo record.
Mission reference: NASA Historical Data Book: Alouette 2 spacecraft and experiments. Editorial review: .
Explorer 31 helped test whether the instruments could coexist
NASA's results report explains that compatibility between a powerful topside sounder and local plasma experiments was not assured before launch. Explorer 31 carried experiments that might be affected by the sounder. Comparison of a duplicated experiment on the two spacecraft showed that Alouette 2's design could support local measurements alongside sounding. This was an instrumentation result as well as an ionospheric investigation.
Reference: NASA NTRS: Alouette 2 and Explorer 31 measurement compatibility.
Reading a restored ionogram requires a second interpretation step
The NASA restoration project provides ionograms, pass headers, and derived electron-density profiles as distinct products. An ionogram trace is not automatically a true-height density profile; the project documents scaling and inversion methods for making that conversion. Select the observation and processing product deliberately rather than treating every colourful archive plot as a direct image of an atmospheric layer.
Reference: NASA SPDF: restored Alouette and ISIS observations and derived profiles.
Reading this orbital snapshot
Based on TLE epoch: 2026-09-04. Estimated altitude ranges from 500 km at perigee to 2,612 km at apogee, a difference of 2,112 km. The orbital period is about 117.2 minutes. Eccentricity 0.13308 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 1.31 times apogee speed. These are mean-element estimates, not instantaneous measurements. Distance per orbit uses an ellipse approximation.
Saved build snapshot. If a valid TLE is retrieved, this explanation and the orbit panel update together. Otherwise this dated snapshot is retained.
Ground track is not sensor coverage
An inclination of 79.80 degrees implies approximate geocentric ground-track limits of 79.8 degrees north and south. This is a prograde orbit, moving in the same general direction as Earth rotation. The plotted line marks the point beneath the object. It does not represent camera coverage, radio reception, or a guaranteed visible pass.
Accuracy and missing information
The introductory record describes the build snapshot. The orbital snapshot explanation and orbit panel share any successfully retrieved TLE; check the displayed epoch. Reentered objects retain historical data only. Mission history is not rewritten by TLE updates. TLE/SGP4 positions are predictions and can change after maneuvers or updated observations. The 14-day stale-data cutoff is a display safeguard, not an accuracy guarantee. Local passes are geometric predictions, not a visibility forecast. No verified operator or mission status means unknown, not active. Do not use this catalog for collision avoidance or operational flight decisions.
Catalog sources: CelesTrak SATCAT: NORAD 1804 · GCAT: S01804 (source update 2026 Sep 4 2345:57). Supplementary metadata: SatNOGS DB, retrieved 2026-09-05T12:57:25.375Z. Page assembled 2026-09-15. GCAT phase codes describe trajectory phases, not mission health.
Learn more: TLE data · Perigee and apogee · Ground tracks · JOT (Jewawud Live Orbital Map)