Solar System

Ion Thruster - Propellant

Xenon is the preferred choice because it is heavy (momentum), inert (won't corrode), and easy to store

Ion Thruster - Specific Impulse ($I_{sp}$)

The "fuel economy" of a rocket

Ion Thruster - Why use them?

Ideal for long-duration missions requiring massive velocity changes ($\Delta v$) where chemical fuel would be too heavy

Ion Thruster - Thrust Level

Very low (comparable to the weight of a piece of paper)

Sample Collection - Microgravity Difficulty

Applying any force (drilling/scooping) creates an equal and opposite reaction that pushes the spacecraft away

Sample Collection - Regolith Behavior

In a vacuum, asteroid dust can behave like a fluid or stick to surfaces due to static electricity

Sample Collection - Signal Latency

Real-time control is impossible due to light-speed delay

RTG (Radioisotope Thermoelectric Generator)

Power source for deep space missions (Voyager, Cassini, New Horizons) that converts heat from decaying Plutonium-238 into electricity via the Seebeck Effect

Gravity Assist (Slingshot)

Using a planet’s orbital momentum to accelerate or decelerate a spacecraft without using fuel

Lagrange Point 2 (L2)

A gravitational "parking spot" 1

5 million km from Earth where JWST stays, keeping the Sun, Earth, and Moon all on one side

Interferometry

The technique of combining signals from multiple telescopes (like ALMA) to act as one giant "virtual" telescope

The "Vault" Concept

Used by Juno

White Ceramic Fiber

Thermal insulation used by BepiColombo to survive the 450°C heat at Mercury

Mission Specifics: BepiColomboBepiColombo - Lead Agencies

Joint mission between ESA (Europe) and JAXA (Japan)

BepiColombo - MPO (Mercury Planetary Orbiter)

The European component focused on mapping the surface and internal composition

BepiColombo - MMO (Mercury Magnetospheric Orbiter)

The Japanese component (Mio) focused on Mercury’s magnetic field

BepiColombo - MOSIF

The sunshield that protects the MMO during the long cruise to Mercury

BepiColombo - Why Mercury is hard

The Sun’s gravity pulls the craft in

Mission Specifics: Galileo & JunoGalileo - Major Discovery

Found strong evidence of a subsurface saltwater ocean on the moon Europa

Galileo - Failure

The High-Gain Antenna (HGA) failed to unfurl

Galileo - Atmospheric Probe

First mission to drop a probe directly into a gas giant's atmosphere

Juno - Primary Goal

To understand Jupiter's origin and evolution by mapping its gravity and magnetic fields

Juno - Core Discovery

Revealed Jupiter has a "dilute" or "fuzzy" core rather than a solid rocky one

Juno - MWR (Microwave Radiometer)

An instrument that "sees" through Jupiter's clouds to measure water and ammonia

Juno - Orbit Type

Polar orbit

Mission Specifics: Cassini & VoyagerCassini - Huygens Probe

An ESA-built probe that landed on Titan, revealing methane lakes and a thick atmosphere

Cassini - Enceladus Discovery

Discovered water-ice plumes erupting from "tiger stripes" at the south pole, indicating a subsurface ocean

Cassini - VIMS

Visual and Infrared Mapping Spectrometer used to map the chemical composition of Saturn's moons

Cassini - Grand Finale

The end-of-mission maneuver where Cassini dove between Saturn and its rings before burning up in the atmosphere

Voyager 2 - Unique Achievement

The only spacecraft to have visited all four outer giant planets (Jupiter, Saturn, Uranus, Neptune)

Voyager 2 - Triton Discovery

Discovered active geysers on Neptune’s moon Triton

Voyager 2 - Interstellar Space

The region it entered where the Sun’s solar wind is replaced by the wind of the galaxy

Mission Specifics: New Horizons & DawnNew Horizons - Pluto Discovery

Found "Sputnik Planitia," a giant heart-shaped glacier of nitrogen ice

New Horizons - LORRI

Long Range Reconnaissance Imager

New Horizons - Power Source

A single RTG, because at Pluto (30+ AU), sunlight is 1000x dimmer than on Earth

Dawn - Main Targets

The "protoplanets" Vesta (rocky) and Ceres (icy/water-rich)

Dawn - Ceres Discovery

Found "faculae" (bright salt spots) in Occator Crater, suggesting recent brine activity

Dawn - Engineering First

The first spacecraft to orbit two different extraterrestrial targets

Mission Specifics: LRO, Hayabusa, Deep ImpactLRO - LOLA

Lunar Orbiter Laser Altimeter

LRO - PSRs

Permanently Shadowed Regions

LRO - LAMP

Lyman-Alpha Mapping Project

Hayabusa - Target

The near-Earth asteroid Itokawa

Hayabusa - Sampler Mechanism

Fired a tantalum bullet into the surface to kick up dust into a collection horn

Deep Impact - Smart Impactor

A 370kg copper slug used to crash into Comet Tempel 1

Deep Impact - Why Copper?

Copper is "spectrally clean"—it doesn't have absorption lines that interfere with the comet's chemistry data

Deep Impact - Discovery

Proved comets are "fluffy" (mostly empty space) rather than solid ice

Mission Specifics: ALMA, Hubble, JWSTALMA - Location

Chajnantor Plateau in the Atacama Desert, Chile, at 5,000 meters altitude

ALMA - Why Altitude?

Millimeter waves are absorbed by water vapor

ALMA - Science Goal

Observing the "Cold Universe," specifically the gas disks where planets are born

Hubble - COSTAR

The corrective optics "glasses" installed by astronauts to fix Hubble’s blurry mirror (spherical aberration)

Hubble - WFC3

Wide Field Camera 3

JWST - Golden Mirrors

Gold is used because it has 99% reflectivity for infrared light

JWST - Sunshield Material

Five layers of Kapton, each the size of a tennis court

JWST - MIRI (Mid-Infrared Instrument)

Needs an extra "cryocooler" to stay at 7 Kelvin to detect faint heat signals

JWST - Main Science Goal

To see "First Light"—the very first stars and galaxies formed after the Big Bang