← INDEX — FIG. 00 — 12 NOVEMBER 2014, 15:34 UT 67P/C–G · 533 kg/m³

COMET
ROSETTA AND PHILAE

Rosetta chased a comet for ten years and landed Philae on it.

BEGIN — CHAPTER 01 →

CH.01 / 08 — LEFTOVERS FROM THE BEGINNING

A cornerstone mission to a different comet than planned

Rosetta was designed to match a comet's orbit and land on it.

Rosetta was redirected to 67P after a launch delay.

CH.02 / 08 — TEN YEARS TO CATCH UP

Four planetary flybys, two asteroids and a long sleep

Rosetta used four planetary flybys.

Rosetta hibernated from June 2011 to January 2014.

DISTANCE FROM THE SUN—

POWER NEEDED (FRACTION OF 1 AU OUTPUT)—

Inverse-square law only.

CH.03 / 08 — ORBITING A MOUNTAIN

Slower than walking, a lap every two weeks

Rosetta became the first spacecraft to orbit a comet; 67P's density is 533 kg/m³.

An orbit at 30 km needs about 15 cm/s.

CIRCULAR ORBIT AND ESCAPE SPEED ABOUT A SMALL BODY

v_c = √(GM/r) · T = 2π r / v_c · v_esc = √(2GM/r) · g = GM/r²

M = 9.982 × 10¹² kg.

ORBIT RADIUS—

CH.04 / 08 — THREE LANDINGS IN TWO HOURS

Philae: every way to hold on failed at once

All three ways for Philae to hold on failed.

Philae bounced and stopped in shadow at Abydos.

REBOUND SPEED—

Rough uniform-gravity estimate.

CH.05 / 08 — WHAT THE COMET IS MADE OF

The wrong kind of water, free oxygen and an amino acid

67P's water has three times Earth's D/H ratio.

Rosetta found molecular oxygen, glycine and phosphorus.

CH.06 / 08 — PERIHELION AND A CONTROLLED LANDING

Riding the comet to the Sun, then joining Philae

Rosetta watched the comet at perihelion in 2015.

On 30 September 2016 Rosetta was guided onto the comet.

CH.07 / 08 — LEGACY: TWELVE YEARS WITH A COMET

From launch to a landing of its own

That is what discovery looks like up close.

CH.08 / 08 — REFERENCES

COMETROSETTA AND PHILAE