Astronomy is driven forward by always asking new questions. When we get to a question that we can’t answer, it usually means that we don’t have the technology, or the knowledge, to get to the bottom of the problem. This drives technology forward. There are constantly bigger and better telescopes being designed and built to answer new questions.
In this activity, you design a new telescope to try and detect sources of gravitational waves! The activity is designed to be completed by a team as part of a STEM Club, but you can have a go on your own if you want to.
By the end of this resource you will:
- know what engineers and astronomers must consider when building a new telescope
- appreciate the challenges involved
- keep to a budget
- use your powers of persuasion
- work as a team to reach a decision
To complete this resource you will need:
- pens/pencils
- scrap paper for drafting ideas
- printed worksheets for recording your decisions
- map and fact files of observing sites
- telescope mirrors information sheet
- fact file of structural materials
Have a go!
Your challenge is to design a new telescope to try and detect sources of gravitational waves!
Background Information
In 2015 the first detection of a gravitational wave was recorded. A gravitational wave is a ripple which travels through the fabric of space (often called space-time) much the same as a ripple travels through water when you drop a stone. They were first predicted by Einstein in 1916 with his theory of relativity. They are made when very massive objects move quickly in space. For the ripples to be strong enough to be detected on Earth, the movement of these objects has to be very fast.
The following events are likely to lead to gravitational waves:
- black holes colliding together
- huge supernova explosions
- neutron stars colliding together
- a neutron star merging with a black hole
Gravitational wave detectors on Earth ‘listen’ out for these events. They can measure the size of the waves and then try to figure out what event caused them. To learn more about this new area of astronomy it is useful to also ‘see’ the events with telescopes. If the source of the waves includes a neutron star or a supernova explosion, then we should be able to see an optical source alongside the gravitational wave detection. This will help scientists to answer questions like:
- Where did the event take place?
- Do gravitational waves travel at the speed of light?
- What is going on inside a neutron star?
- How do stars actually explode?
Instructions
The budget for your telescope is £150 million (did you know the James Webb Space Telescope cost more than £7 billion!). As a team, you must decide how best to spend your money. You must make the following decisions:
- Where will it be built? What is your backup in case you go over budget?
- What is the design of your mirror? What is your backup?
- What material will you use to build the telescope structure? What is your backup?
- Are you sure your choices are within budget?
1. In order to detect the maximum number of gravitational wave sources it is important for the observing site to be close to the equator, from which both the northern and southern hemispheres can be observed. Use the map and fact files to reach and decision a record it on the Activity 1 page of the decision worksheet.
2. Gravitational wave sources can come from very distant objects. The bigger the diameter of the telescope's mirror, the more light it can collect, enabling you to see fainter objects. Your mirror must have an effective diameter of at least 8 metres to detect the source's gravitational waves. Use the mirror information sheet to reach a decision and record it on the Activity 2 page of the decision worksheet.
3. Gravitational wave sources are also likely to emit flashes of optical light, which appear and then fade very quickly. This means that the telescope needs to move very quickly to see the light before it disappears. The materials need to be strong enough to support the mirror, but light enough to move at speed. Use the materials fact file to reach a decision and record it on the Activity 3 page of the decision worksheet.
4. Total up the cost of your choices and write them on the Activity 4 page of the decision worksheet. If you need to, substitute some of your backup choices to keep your plan within budget.
Congratulations! You've designed a telescope to detect the sources of gravitational waves!