Octant

Scenario

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Central body

The body every orbit is defined around and propagated about — a physics setting, not a view one. Changing it rewrites the scenario, so it asks first. To look at another body without changing what is being modelled, use the camera control above the map.

Objects

Nothing selected—

Orbit

Perigee altitude 700 km Inclination 98.2° RAAN 0° Argument of perigee 90° True anomaly 0° Where the spacecraft sits in its own orbit. Satellites sharing a plane differ only by this. Eccentricity 0.0010

Instruments

No instrument, so no cone and no swath. A footprint is a claim about what hardware sees — add one, or attach a vehicle that carries one.

Pointing Nadir and fixed off-nadir sweep, so they draw a swath. The target laws stare at one place, so they draw a footprint instead. Max slew rate Degrees per second the spacecraft can actually turn. These are pointing laws, not a control system — this is the stated limit they are checked against. —

Vehicle

Fidelity A point mass is the cannonball model: three numbers and no geometry. Building it from parts derives the same three, and is what panels, antennas and thrusters need to exist on — so power, access and finite burns are only offered on a built vehicle. — Mass, drag area and ballistic coefficient are derived from the parts.

Coverage

ΔV budget

Disposal & compliance

Data budget

Link budget

Coding Rate kbps Bandwidth MHz

Mission phases

A phase is a stretch of the window with its own commands, and a burn happens at the boundary between two. One phase is an ordinary scenario; the propagator hands the state at the end of each phase to the next, so a burn changes the orbit that follows it.

Drag

C_d Area m² Mass kg

Drag properties. The lifetime they feed is an analysis, and it lives with the other analyses in the chart dock below.

Coverage grid

Compute and show it

Cell size Colour by

Sun above (°)

Only while the spacecraft is in sunlight

Cells are coloured red where the worst wait is long and cyan where it is short; unseen cells stay dark. It uses the same swath geometry the corridor on the globe is drawn from, so the two cannot disagree.

Conjunctions

Warn below (km)

Every pair of spacecraft in the scenario, over the whole window. A screen is only as fine as its sampling: an approach that happens between two samples is refined, but one that begins and ends between them is missed entirely. The card says which sampling it used.

Transfer window

From To

Depart within (days) Flight time (days)

Park at (km) Capture into (km)

Each cell is one departure date and one flight time; the colour is the total v-infinity, cyan cheap to red dear. Cells far above the best are left dark rather than scaled, because a porkchop plot is read for where the island is. Departure runs left to right, flight time bottom to top. Click a cell to price it.

Close approaches

Each bar is one pass, and its LENGTH is what is not known: the bar spans JPL's 3-sigma range of miss distance and the notch is the nominal figure. A near-invisible bar is a pinned orbit; one running off the edge is an object seen for a few nights. The dashed line is the Moon's distance. This is a range, not a b-plane ellipse — the covariance that would give a shape is not published here.

Impact risk

Palermo is a LOG RATIO against the background risk from bodies of similar size, so 0 means “as likely as what arrives unannounced anyway” and negative is below it. Torino is a different scale: it ignores time-to-impact and is undefined beyond 100 years. JPL’s own caveat applies to every figure here — the probability computation “can easily be inaccurate by a factor of a few, and occasionally by a factor of ten or more”, and diameters derived from absolute magnitude are good to about a factor of two. The ESA NEOCC risk list is the natural second opinion and is not shown: ESA grants no right to redistribute its data or to build derivative works from it, and neither agency sends the headers a browser needs to fetch it directly. The comparison is run offline instead.

Apophis 2029, from our own orbit

Deflection

Impulse along track (mm/s) Years before encounter

A kinetic impactor barely moves an asteroid. What it changes is the orbital period, and a period wrong by seconds becomes an arrival wrong by hours once it has had years to accumulate — which is why the lead time matters far more than the impulse. The displacement quoted is ALONG the orbit; how much of it becomes extra miss distance depends on the encounter geometry, which this does not model.

Your scenario saves to a versioned .json you keep, from Save… at the top. It is also held in this browser and restored next visit.

The CSVs carry positions as computed, one row per sample, and the contact windows one row each. The OEM is a second propagation that asks the engine for velocities rather than differencing positions — at this sampling those differ by 4.7 m/s. Encodes the whole scenario. No account, nothing stored.

Central body —

Change the central body to ?

Open a scenario

Vehicle for —

Orbit for —

Or a real spacecraft

Or a near-Earth object

Add a spacecraft

What Octant is doing

Objects

Targets

Swath and access are different things

Time

What it does not model

Vehicle

Bus

Parts

Propellant

3D model

Time scales

State format

Reference frame

Component

Asset library