Bellwork 12/22 What kinds of design differences would there be in planning a mission to Jupiter versus sending a satellite into Earth’s orbit?

Upcoming schedule: Today: Wednesday 1/4 Friday 1/6 Monday 1/9 Quick intro to Rockets & Gravity assist Work time Wednesday 1/4 Quick intro to Equipment Friday 1/6 Presentations due at the BEGINNING of class Present your missions  Monday 1/9 Finish up any residual presentations Review for Final Exam

Bellwork 1/9 A scientist is planning a manned mission to study the existence of water on Enceladus. Which of the following pieces of equipment could be useful and why? a. Rover with camera and mineral analysis equipment b. Telescope with IR & UV imaging capability c. Orbiting satellite to measure temperatures and atmospheric chemical composition d. All of the above

The Plan: 1/3: Ethics & Mission Background Research 1/5: Introduction to Equipment 1/9: Trajectory & Gravity Assist 1/11 & 1/16: Work days 1/18: Presentations!! 1/22: Skinny Day—Review for final exam

So, now that we know what to do when we’re in space… How do we get there?

How do we get an object from Earth into space? Rockets! Rockets carry objects to a certain height and then eject whatever is to be sent into space Often built in “stages” that fall off and parachute back to Earth Can carry shuttles, satellites, ect.

What is a Rocket? A chamber enclosing a gas under pressure. A balloon is a simple example of a rocket. Rubber walls compress the air inside. Air escapes from the small opening at one end and the balloon flies.

How Do Rockets Work A rocket moves forward when gases shooting out the back of the rocket push it in the opposite direction. The reaction force that propels a rocket forward is called thrust. The greater the thrust, the greater a rocket’s velocity.

F=mA The mass of the rocket changes during flight. As fuel is rapidly used and expelled, the rocket weighs less and accelerates. Thrust continues until the engine stops firing. Mass Force Acceleration Thrust Force produced as fuel rapidly exits, accelerates rocket.

Action and Reaction A rocket takes off only when it expels gas. Action: The rocket pushes the gas out of the engine. Reaction: The gas pushes up on the rocket. The Action (Thrust) has to be greater than the weight of the rocket for the reaction (liftoff) to happen. Newton’s 3rd Law

Types of Rockets NASA uses: Atlas V Delta II Soyuz Rocket (Russian rocket which is used to transport people/supplies to the ISS NASA’s Space Shuttle program ended in 2011 Challenger & Columbia explosions Budget cuts

How fast does it need to go? Escape Velocity: The speed at which an object must travel to break free of a planet’s gravity Earth’s escape velocity 40,000 Km/h 11.2 Km/s 25,000 mph

For objects that just need to orbit Earth, meeting the Escape Velocity enough…

How do we get into “Deep Space”? Gravity Assist Using a planet's motion to accelerate a satellite As a satellite heads toward a planet, it accelerates. As it moves away from a planet, it decelerates So…how does this help? https://www.youtube.com/watch?v=5ceD56b1LD8

Why use Gravity Assist? Saves on fuel, time, and expenses! Direction changes, speeding up, slowing down, stabilizing against minor collisions/gravitational effects of other objects All of these things require fuel! We’ve already addressed that you can only take so much with you into space…

Trajectories Planning the timing of a launch depends on many factors: Planetary alignment & speeds Destination Fly by vs. landing Solar needs (will the sun be in the way of imaging? Do you need sunlight to get the image?) Spacecraft’s payload & maximum velocity

Example: Sending Curiosity to Mars Launched on Nov. 6th 2011; landed in Gale Crater on Aug. 6th 2012 This launch date minimized the duration of the trip—occurs roughly every 26 months A later (or earlier) launch could result in the spacecraft “missing” or overshooting Mars

Let’s take a closer look at how gravity assist works and how it has been used: Gravity Assist/Trajectory Activity Posted in the Google Classroom