← INDEX — FIG. 00 — 15 DECEMBER 1970, 05:34 UT 92 bar · 737 K · 96.5 % CO₂

FURNACE
VENERA AND VEGA

The surface of Venus is hot enough to melt lead.

BEGIN — CHAPTER 01 →

CH.01 / 10 — EARTH'S TWIN, GONE WRONG

Same size as Earth, a different world

Venus has 92 bar and 737 K at the surface.

None of this was known in 1960.

CH.02 / 10 — FALLING THROUGH A CO₂ OCEAN

So dense near the ground that a disc is enough to land

The landers discarded their parachutes at 46–50 km; a disc was enough.

Temperature and pressure from VIRA; speed from weight and drag.

DENSITY AND TERMINAL SPEED

ρ = p M / (R T) · v_t = √(2 g K / ρ) · K = m / (C_D A) · t = ∫ dh / v_t(h)

M = 0.04401 kg/mol, g = 8.87 m/s².

ALTITUDE—

MASS PER DRAG AREA K—

VIRA values every 5 km.

CH.03 / 10 — THE FIRST PROBE INSIDE ANOTHER PLANET

Venera 4: built for an atmosphere that did not exist

Venera 4 transmitted for 93 minutes from inside the atmosphere.

It fell silent at about 28 km; every later Venera was built for the surface.

CH.04 / 10 — HOW TO BUILD A SPHERE THAT WILL NOT BE CRUSHED

Strength is not the problem. Stability is.

Venera 7 was built for 150–180 atm; a sphere carries stress pR/2t.

Under external pressure, buckling sets the wall thickness.

THIN SPHERE UNDER EXTERNAL PRESSURE

t_strength = S · p R / (2 σ_y) · p_cr = k · 2E (t/R)² / √(3(1−ν²)) ⇒ t_buckling = R √( S p √(3(1−ν²)) / (2 k E) )

Room-temperature properties.

DESIGN PRESSURE—

SPHERE RADIUS—

KNOCKDOWN FACTOR k—

Typical handbook values.

CH.05 / 10 — A SIGNAL FROM THE SURFACE

Twenty-three minutes hidden in the noise

Venera 7 hit the ground at 17 m/s.

22 min 58 s of data were found in the noise.

CH.06 / 10 — DAYLIGHT, THEN THE FIRST PICTURES

Is it light enough down there to take a photograph?

Venera 8 showed sunlight reaches the ground.

Venera 9 sent the first picture from another planet's surface.

CH.07 / 10 — HOW LONG EACH ONE LASTED

A race between the insulation and the oven

Every minute on the surface was bought with mass.

Venera 13 lasted 127 minutes against a 32-minute design.

CH.08 / 10 — BALLOONS IN THE CLOUDS, THEN A COMET

Vega: two landers, two balloons and Halley's Comet

Each Vega dropped a lander and a balloon that floated near 54 km.

Each balloon flew 46.5 hours; the buses went on to Halley's Comet.

BUOYANCY

m = V (ρ_CO₂ − ρ_He) ⇒ V = m / (ρ_CO₂ − ρ_He) · D = (6V/π)^1/3

Both gases at local T and p.

FLOAT ALTITUDE—

TOTAL FLOATING MASS—

CH.09 / 10 — LEGACY: EIGHTEEN YEARS INTO THE FURNACE

From a crushed capsule to colour pictures and balloons

Each probe was designed for the planet the last one had revealed.

CH.10 / 10 — REFERENCES

FURNACEVENERA AND VEGA