ANTARCTIC IMPACT
MODEL WORKSHOP / 01

Account for every
part of the comet.

The book describes a core lodged beneath Wilkes Land and a mantle spreading outward. Test how much material each part could carry before adding more detail to the model.

CONDITIONAL MASS BUDGET

Start with the book’s working body. Change the unknown shares. Every trial conserves mass and keeps its assumptions visible.

Read the source calculation ↗
FOLLOW THE MATERIAL

One body. Three destinations.

ALL MASSES IN kg
Whole incoming body—
01 / Core—

Assigned to the coherent remnant.

02 / Retained mantle—

Available for a bulk-mass comparison.

03 / Remainder—

Not retained in this ledger; fate unresolved.

Core + retained mantle + remainder = whole body.

COMPARE WITH THE BOOK

Is there enough bulk material?

—

Calculating…

Body diameter needed at these shares & density—
Largest core share with enough bulk mass, at this body size & mantle retention—

This compares total mass only. Nitrogen ice and water are different materials; matching these totals does not establish water delivery, chemical conversion or an ice-sheet history.

Inspect the incoming kinetic energy

At the same incoming speed for both parts, E = ½Mv². These are pre-contact energy shares, not energy delivered to the crust.

Whole body
—
Core share
—
Mantle share
—

The 3D trial carries the body inputs and explicit shares. The linked wave and direct spin use the core’s mass, speed and entry direction. The separate tracked gas inventory retains whole-body mass; the energy-to-continental-motion mapping is an explicit illustrative response.

SOURCE & ARITHMETIC

Keep the book
beside the calculation.

Chapter Three lists the three inventories below. Treating them as separate quantities gives the comparison target. They are the book’s stated values, without an independent measurement audit here.

“Estimating the Antarctic Comet” ↗
Antarctic ice
2.76 × 10¹⁹ kg
Greenland ice
2.62 × 10¹⁸ kg
Sea-rise water
3.30 × 10¹⁹ kg
Sum of listed values
6.322 × 10¹⁹ kg
Book’s quoted diameter~576 km
Calculated from listed masses—

The book rounds the total to ~6 × 10¹⁹ kg and quotes ~576 km at 1,000 kg/m³. Its listed masses instead give ~494.26 km at that density. The calculation above uses your density and assumes the entire equivalent sphere is inventory material, with no core or loss. The manuscript’s statement remains unchanged.

CHANGE ONE THING

Small size changes.
Large mass changes.

Compare diameters 20% below and above your trial, holding density, speed and shares fixed. Mass scales with diameter cubed; energy also scales with speed squared.

Whole-body diameterBody massRetained mantleCore energy
HOW THE MODEL GETS BETTER

Make each next step testable.

  1. 01

    Anchor the starting values.

    Keep each number linked to its passage, and distinguish a stated value from a derived result.

  2. 02

    Constrain the unknown shares.

    Core mass, mantle retention and material composition need evidence before they can become fitted model inputs.

  3. 03

    Connect mass to motion.

    A later fragmentation and impact model must account for momentum, energy transfer, material phases and escape before predicting deposits or fractures.