Skip to main content
  • The Open University
  • Accessibility hub
  • Guest user / Sign out
  • Study with The Open University
  • Accessibility hub
Close OpenLearn will be unavailable from 8am to 10.30am on Wednesday 3 September due to scheduled maintenance.
Skip to content
  • The Open University
  • Accessibility hub
  • Guest user / Sign out
  • Study with The Open University
  • Accessibility hub
Close OpenLearn will be unavailable from 8am to 10.30am on Wednesday 3 September due to scheduled maintenance.
header search
  • Home
  • Free courses
    • All our free courses
    • Badged courses
    • Why study a free course on OpenLearn?
    • Advantages of enrolling on a free course
    • Frequently asked questions
    • Study with The Open University
  • Subjects
  • Study skills
  • Work skills
  • Help
  • Accessibility hub
  • Sign in
Create account / Sign in
ahihi OpenLearn
  • The Open University
  • Accessibility hub
  • Guest user / Sign out
  • Study with The Open University
  • Accessibility hub
Close OpenLearn will be unavailable from 8am to 10.30am on Wednesday 3 September due to scheduled maintenance.
OpenLearn
  • Home
  • Free courses
    • All our free courses
    • Badged courses
    • Why study a free course on OpenLearn?
    • Advantages of enrolling on a free course
    • Frequently asked questions
    • Study with The Open University
  • Subjects
  • Study skills
  • Work skills
  • Help
  • Accessibility hub
  • Sign in
Menu
sticky search

My OpenLearn Profile

Personalise your OpenLearn profile, save your favourite content and get recognition for your learning

Create account / Sign in
  • Subjects
  • Science, Maths & Technology
  • Free courses
  • Moons of our Solar System
  • Moons of our Solar System
  • 1.7 Penetrators at work

Course content

  • Moons of our Solar System
  • Introduction and guidance
    • Introduction and guidance
      • What is a badged course?
      • How to get a badge
  • Week 1: What are moons?
    • Introduction
    • 1 Fascinating bodies
      • 1.1 Getting started with moons
      • 1.2 Thinking about Europa
      • 1.3 Mythbusting moons
      • 1.4 The first picture show
      • 1.5 Waltz Around Saturn
      • 1.6 What do you know?
    • 2 Moons and planets
      • 2.1 The Moon’s orbit
      • 2.2 Prograde orbits
      • 2.3 Orbital inclination
      • 2.4 Retrograde orbits
      • 2.5 Triton’s orbit around Neptune
      • 2.6 Synchronous rotation
      • 2.7 Rings around planets
      • 2.8 Are ring-particles moons?
      • 2.9 Small bodies can have moons
      • 2.10 Moon phases and libration
      • 2.11 How the Moon’s phases look from the Earth
      • 2.12 The crescent Moon seen from the Equator
    • 3 What makes a moon?
      • 3.1 The Moon’s origin
      • 3.2 Forming other moons
      • 3.3 Triton – a moon with a difference
      • 3.4 Pluto’s eccentric orbit
      • 3.5 Pluto and Charon
      • 3.6 Bombardment history
      • 3.7 A very Nice model
      • 3.8 What is a tide?
      • 3.9 Spring and neap tides
      • 3.10 Tidal heating explained
      • 3.11 Tidal effects on Io and Europa
      • 3.12 Investigating orbital resonance
      • 3.13 Moons data
      • 3.14 Orbital resonances at Saturn?
    • 4 This week’s quiz
    • 5 Summary
  • Week 2: Looking at moons
    • Introduction
    • 1 Ice and rock – distance from the planet
      • 1.1 Inside a moon
      • 1.2 Distance from the Sun is important too
      • 1.3 Ice and Ganymede
      • 1.4 Icy moons
      • 1.5 Shapes of moons
      • 1.6 Naming moons
      • 1.7 Sizing moons
    • 2 Our Moon and its craters
      • 2.1 Craters on the Moon’s surface
      • 2.2 Galileo’s thoughts
      • 2.3 Comparing craters
      • 2.4 Meteor Crater, Arizona
      • 2.5 How impact craters form
      • 2.6 Gene Shoemaker at Meteor Crater
      • 2.7 Making an impact
      • 2.8 Impact mechanics
      • 2.9 Crater morphologies
      • 2.10 Examples of crater shapes on the Moon
    • 3 Lots of little impacts
      • 3.1 One ‘big’ impact
      • 3.2 Scarce craters
      • 3.3 Why some craters are big
      • 3.4 Surface gravity
    • 4 Crater sizes
      • 4.1 A changing moonscape
    • 5 This week’s quiz
    • 6 Summary
  • Week 3: Looking closer
    • Introduction
    • 1 Volcanism in the Solar System
      • 1.1 Past volcanism on the Moon
      • 1.2 Present volcanism on other moons
      • 1.3 Volcanic eruptions on Io
      • 1.4 A closer look at volcanism on Io
      • 1.5 Cryovolcanism on Enceladus
      • 1.6 How Enceladus works
      • 1.7 Some other cryovolcanic moons
    • 2 Discovery of Europa
      • 2.1 Nobody expects the Italian inquisition
      • 2.2 See for yourself!
      • 2.3 Europa’s surface
      • 2.4 What the images mean
      • 2.5 Is Europa habitable?
      • 2.6 Is Lake Vostok like Europa?
      • 2.7 Where might life be found on Europa?
      • 2.8 Hydrothermal vents too?
      • 2.9 Eruption plumes on Europa?
      • 2.10 Moon Trumps
    • 3 Phobos and Deimos
      • 3.1 The groovy moon
      • 3.2 Phobos seen from the surface of Mars
      • 3.3 The moons of asteroids
      • 3.4 Exploring Saturn’s moons with Cassini–Huygens
      • 3.5 Ordering Saturn’s moons
      • 3.6 Naming Charon
      • 3.7 Naming Pluto’s other moons
      • 3.8 What’s in a name?
      • 3.9 The New Horizons mission
    • 4 This week’s quiz
    • 5 Summary
  • Week 4: Our Moon
    • Introduction
    • 1 The Moon’s influence on us
      • 1.1 Inspirational moons
      • 1.2 A moon among many?
      • 1.3 The Moon – some facts
      • 1.4 Inside the Moon
      • 1.5 Looking at the Moon
      • 1.6 Going to the Moon
    • 2 Race to the Moon
      • 2.1 What’s it like on the Moon?
      • 2.2 Weighing objects on the Moon
      • 2.3 Falling objects on the Moon
      • 2.4 Experiments on the Moon
      • 2.5 Where next?
    • 3 Departure from the Moon
      • 3.1 Re-entry
      • 3.2 Apollo 13
      • 3.3 Bringing Moon samples to Earth
      • 3.4 Why bother bringing rocks back to Earth?
      • 3.5 Handling pieces of the Moon
      • 3.6 Storage on Earth
    • 4 This week’s quiz
    • 5 Summary
  • Week 5: What we learned from the Moon
    • Introduction
    • 1 What we’ve learned about the Moon
      • 1.1 An ocean of magma
      • 1.2 The Genesis Rock – a key find
      • 1.3 The Genesis Rock – how it was found
      • 1.4 Anyone for golf?
      • 1.5 Lunar mantle fragments at the surface
      • 1.6 Rocks that form the Moon’s surface
      • 1.7 Mare basalt formation
    • 2 Why study Moon rocks?
      • 2.1 Moon rocks – a scientist’s view
      • 2.2 Minerals under the microscope
      • 2.3 Moon rocks under the microscope
      • 2.4 Your first moon rock – a mare basalt
      • 2.5 Highland rock
      • 2.6 Lunar regolith sample
      • 2.7 Lunar regolith – a second sample
    • 3 Unravelling the Moon’s history
      • 3.1 Radiometric dating of Moon rocks – some background
      • 3.2 Get a half-life!
      • 3.3 Radiometric dating of complex Moon breccias
      • 3.4 Remote sensing – crater counting
      • 3.5 Crater counting in detail
      • 3.6 History of the Moon
    • 4 This week’s quiz
    • 5 Summary
  • Week 6: Water on the Moon
    • Introduction
    • 1 Early theories about water on the Moon
      • 1.1 Dry rocks
      • 1.2 What happened to this lunar basalt?
      • 1.3 Patchy evidence
      • 1.4 How does science advance, and how do we know when it happens?
      • 1.5 A little dust goes a long way
      • 1.6 A paradigm shift?
    • 2 Odd craters
      • 2.1 Looking for water from lunar orbit
      • 2.2 Ice in polar craters on the Moon
      • 2.3 More missions – detail and resolution
      • 2.4 Results from the Lunar Prospector mission
      • 2.5 The SELENE mission
      • 2.6 Results from SELENE
      • 2.7 The Chandrayaan-1 mission
      • 2.8 Results from Chandrayaan-1 and LCROSS
      • 2.9 Where does water on the Moon’s surface come from?
      • 2.10 How much water?
    • 3 Water from a stone
      • 3.1 Water in lunar minerals
      • 3.2 Uses for water on the Moon
      • 3.3 The future of lunar exploration
      • 3.4 The economics of it
      • 3.5 Making rocket fuel
    • 4 This week’s quiz
    • 5 Summary
  • Week 7: Exploring moons
    • Introduction
    • 1 Finding new moons
      • 1.1 The Grand Tour
      • 1.2 Voyager
      • 1.3 Voyager – inspiring generations
      • 1.4 Voyager – last picture show
      • 1.5 The Galileo mission
      • 1.6 Cassini–Huygens
      • 1.7 Cassini–Huygens – 15 years of exploration
    • 2 Titan – a new area of exploration
      • 2.1 Titan and its atmosphere
      • 2.2 The surface of Titan
      • 2.3 Descent to Titan
      • 2.4 Surface features revealed by Cassini–Huygens
      • 2.5 Making plans for Titan
      • 2.6 A look at Triton
    • 3 Rhea, Miranda and Ariel
      • 3.1 Rhea
      • 3.2 Miranda
      • 3.3 Ariel
    • 5 This week’s quiz
    • 4 Summary
  • Week 8: Moons and the future
    • Introduction
    • 1 Flights of the imagination
      • 1.1 Humans or robots?
      • 1.2 The Moon goddess and the Jade Rabbit
      • 1.3 How small? How expensive?
      • 1.4 The JUICE mission to Jupiter
      • 1.5 Splashdown on Titan?
      • 1.6 Moon artillery
      • Current section:
        1.7 Penetrators at work
      • 1.8 Ice penetrators
      • 1.9 New Horizons in the making
      • 1.10 New Horizons Pluto–Charon flyby
      • 1.11 Pluto and friends
      • 1.12 Moon Trumps again
    • 2 Life, what is it?
      • 2.1 Life chemistry
      • 2.2 Markers of life
      • 2.3 Lessons from Earth
      • 2.4 Fossil molecules
      • 2.5 The habitable zone
      • 2.6 Habitable Earth
      • 2.7 Habitable places
      • 2.8 Europa
      • 2.9 Ganymede
      • 2.10 Titan
      • 2.11 What Huygens found on Titan
    • 3 What’s the Buzz?
      • 3.1 Presentation recording
    • 4 This week’s quiz
    • 5 End-of-course round up
  • Acknowledgements
  • course image File
  • share image File
  • thumbnail image File

About this free course

About this free course

24 hours study

Level 1: Introductory

Full course description

Become an OU student

Become an OU student

  • BA/BSc (Honours) Open degree
    BA/BSc (Honours) Open degree
  • Certificate in Astronomy and Planetary Science
    Certificate in Astronomy and Planetary Science

Download this course

Download this course

Download this course for use offline or for other devices

  • WordWord
  • PrintablePDF

Share this free course

Share this free course

Share on Facebook Share on Twitter Share on LinkedIn Share via Email

Course rewards

Free statement of participation on completion of these courses.

Badge icon

Earn a free Open University digital badge if you complete this course, to display and share your achievement.

Create your free OpenLearn profile

Anyone can learn for free on OpenLearn, but signing-up will give you access to your personal learning profile and record of achievements that you earn while you study.

Sign up now for freeSign up now for free

Newsletter

Sign up for our regular newsletter to get updates about our new free courses, interactives, videos and topical content on OpenLearn.

Newsletter sign-up

Course content Course content
Moons of our Solar System
Moons of our Solar System

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Create account / Sign inMore free courses
  • Week1
  • Week2
  • Week3
  • Week4
  • Week5
  • Week6
  • Week7
  • Week8

1.7 Penetrators at work

In collaboration with Astrium UK and the Mullard Space Science Laboratory (in London), the instruments housed in penetrators have undergone a series of impact tests into compact sand and ice targets to simulate conditions on places such as the Moon and Europa.

Even after a penetrator was fired at just under the speed of sound, the structure and instruments inside remained intact after the impact, proving the technology to get functioning instruments to the surface of another body in this way. They are much less heavy than conventional landing systems, so more can be achieved for the same mass. This concept will be developed in the next few years, when power and communication systems will also be researched.

This video has no sound

Download this video clip.Video player: moons_1_vid060_ebook.mp4
Click or press enter to start the media player
Interactive feature not available in single page view (see it in standard view).
PreviousPrevious 1.6 Moon artillery
Next 1.8 Ice penetratorsNext
Take your learning further

Ready to take the next step in your learning journey?
With over 50 years of experience in distance learning, The Open University brings flexible, trusted education to you, wherever you are. If you’re new to university-level study, read our guide on Where to take your learning next.

Join over 2 million students who’ve reached their goals with us.

Browse all Open University courses and start your journey today.

Back to top

footer Menu

  • Get started

    • Get started with OpenLearn
    • New to OpenLearn
    • Try something popular
    • All our free courses
    • Badged courses
    • Free learning hubs
    • Games, quizzes & activities
    • Subscribe to our newsletter
    • OpenLearn Cymru
  • Explore subjects

    • Digital & Computing
    • Education & Development
    • Health, Sports & Psychology
    • History & The Arts
    • Languages
    • Money & Business
    • Nature & Environment
    • Science, Maths & Technology
    • Society, Politics & Law
  • About OpenLearn

    • About us
    • Frequently asked questions
    • Study with The Open University
    • Contact OpenLearn
    • OpenLearn Create

Our partners

OpenLearn works with other organisations by providing free courses and resources that support our mission of opening up educational opportunities to more people in more places.

Find out more

Support us

Policy

  • Twitter
  • Facebook
  • YouTube

©1999-2025. All rights reserved. The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority in relation to its secondary activity of credit broking.

  • Accessibility statement
  • Conditions of use
  • Privacy and cookies
  • Modern Slavery Act
  • Copyright
  • Manage cookie preferences
invalidsesskey
Your session has most likely timed out. Please check if you are logged in or go back to the previous screen and reload the page.
    Share on Facebook Share on Twitter Share on LinkedIn Share via Email