Animated screen capture showing a line being drawn on a map of Mars.

Image credit: NASA/JPL-Caltech | + Expand image

It's a tough job driving a Mars rover – not just because of the complexity of these robotic explorers, but also because of the distance between Earth and the challenging terrain that we’re trying to cross. To determine the best and safest path for our rovers, we rely largely on satellite imagery from spacecraft orbiting the Red Planet such as the Mars Reconnaissance Orbiter that give us a look at what lies ahead.

In this activity, you will plan your own path for the rover to see just how challenging it can be to get from one place to another on Mars.


1. Learn how we drive Mars rovers

Where's the driver's seat for a Mars rover? Millions of miles away, back on Earth! Learn more in this 60-second video. | Watch more Mars in a Minute

Due to the enormous distance between Earth and Mars, navigating rovers on another planet brings a lot of challenges.

First, we can't drive Mars rovers in real time using something like a joystick. This is because we're limited by the speed of light, so any instructions that we send to the rover will take about three minutes to arrive. Instead, we send “packages” of directions for the rover to follow.

Secondly, we have to use the rover's cameras as our "eyes" on the ground. While the cameras can capture a lot of great detail, they can only see so far, and it can still be very difficult to pick the safest path in an unfamiliar environment.

To help us get a better view of the area around the rovers, we use orbiting satellites, such as the Mars Reconnaissance Orbiter, or MRO. These orbiters fly around Mars and provide an overhead look at the rovers' surroundings. Using Mars orbiters like MRO, we can create incredibly detailed maps of the Martian surface, similar to how we create maps of Earth using satellites.

This interactive map shows the landing site for NASA's Perseverance rover within Jezero Crater and its path to its current location. Perseverance landed on Feb. 18, 2021. The map also shows the location of the Mars Helicopter. | › Learn more

Screengrab from Mars Trek showing the default Mercator projection map of Mars.

2. Get set up with Mars Trek

Using an internet-capable laptop or desktop computer, go to the Mars Trek website.

A pop-up window will load, inviting you to do a tutorial. If this is your first time visiting the site, you may want to accept, otherwise you can select Skip Tutorial.

Next, you’ll see what is called a Mercator projection map, which takes a 3D globe and stretches it onto a 2D surface where the entire globe is visible in one view. Note: In a Mercator projection, there is a large distortion at the poles, which are stretched to the four corners of the image. The area around the equator is the least distorted.

+ Expand image (top)

Screengrab of Mars Trek zoomed in on the Perseverance landing site.

3. Explore the map layers

In the top left corner, you’ll see the Data icon. Selecting this opens a menu that will allow you to add various map layers that NASA scientists have created over decades of Mars exploration by robotic spacecraft.

You’ll notice you can search by all layers, or you can select Product Type and filter by category. For example, try searching for the Perseverance Mars rover's landing site. Select it to see some background information about the mission. Click the Add button at the bottom to add a map marker where the rover successfully landed.

After you’ve added the Perseverance landing marker, close the Data window using the red X. Then click on the Basemaps icon in the bottom-right corner of the screen. Here you can see the default map layer you have active. Use the Nomenclature toggle to add text labels to your map. Zoom out using the controls on the lower-left side of the screen to see what text was added.

+ Expand image (top)

Screengrab from Mars Trek with the topographic layer visible.

4. Explore the topography

You may have already started to get a feel for just how treacherous the Martian terrain can be. It's filled with craters and cliffs that could prove hazardous to rovers. To get a more detailed picture of these hazards, we’ll add a topographic layer to our map. Topography is the study of the shape and features of the land.

Open the Data menu again, search for "MGS MOLA and Mars Express HRSC, Color Hillshade Blend," and add it to your map. This data was collected by the Mars Orbiter Laser Altimeter, or MOLA, instrument aboard NASA's Mars Global Surveyor orbiter. It uses a laser to measure the highest peaks and lowest valleys on Mars.

Try adding any other layers that look interesting to you. What information do they provide?

To remove layers, select Layers in the middle of the Data window and select the X icon to delete any you no longer want. You can also toggle the layers on and off using the eye icon. If you have several layers on top of each other, you can use the slider under each layer to change the transparency to simultaneously view multiple layers at once.

+ Expand image (top)

Screengrab from Mars Trek showing the line measurement option being selected.

5. Measure distances

You can calculate both distance and topography using your map.

Let's try, for example, measuring how far it is from the Perseverance landing site to Syrtis Major Planum to the southwest. Select the Menu icon in the upper right of the screen and then click on Calculate Distance. Select Line, then click on the rover's location and hold your mouse down to draw a straight line from the rover to Syrtis Major Planum.

This a long distance for the rover, which has a top speed of about 152 meters per hour on flat hard ground, less than 0.1 miles per hour.

Also notice that the color on the topographic map changes from green where Perseverance is located to orange at the destination we selected. This difference in color represents the relative elevation on the surface. To calculate the elevation change along the path you've drawn, click on the line and select Elevation Profile Calculation from the menu that pops up. Click Submit to get a graph showing how the elevation changes over the course of your route.

In this example, that's one steep climb – a difference of 4,000 meters at the greatest peak! The rovers would almost never attempt any angle greater than 30 degrees, making this far too difficult of a climb for our rovers.

See if you can make the climb less steep by using the Freehand Polyline option when choosing Calculate Distance from the Menu. This way, you can create a path that uses arcs or waypoints instead of a straight line. This will also help you navigate around craters or otherwise harsh terrain. Are you able to help the rover find a more mild path?

Note: You can remove paths by clicking on the line and choosing Remove Marker from the popup menu.

Now, try doing the same within the Perseverance rover's more immediate landing area inside Jezero crater. Use the Freehand tool to draw a path that would allow Perseverance to get from its landing site to the rim of Jezero crater. Can you locate any natural channels that may present a safe path?

+ Expand image (top)

Screengrab from Mars Trek showing the minerals layer turned on.

6. Where to go next?

Now that we have some practice creating safe routes to landmarks on Mars, it’s time for us to pick a scientifically interesting destination. Let’s add another layer that will identify some of the interesting geology we may want to explore further with our rover.

In the Data menu, search for and add the layer “Aqueous Mineral Distribution.” This layer shows types of rocks and minerals by category across the entire Martian surface.

Note: If your map is getting too crowded, remember you can toggle off your layers and/or change their transparency to help you see better.

In the Layers window, you can select Toggle Legend (list icon) to see which colors correspond to which minerals of interest.

Try adding a new layer showing the Curiosity rover's landing site. (Curiosity landed on Mars 9 years before Perseverance and is exploring a very different location with very different types of minerals.) Answer the questions below using the new map layer and the skills you've learned so far.

+ Expand image (top)

Animated illustration of the Curiosity rover driving on Mars.

7. Blaze your own trail

Now it’s time for you to decide which scientific targets look the most worthy of exploration! Select a layer that looks interesting to you, and plot a course to safely reach it. Remember to consider the terrain and how to best keep your spacecraft safe during your journey.

You can save your map to edit or view later by going to the Menu and selecting Share Link or Screen Capture, respectively.

+ Expand image (top)

Screengrab of the Solar System Treks homepage.

8. Explore more

Explore similar treks at other destinations across our solar system.

And read more about Mars exploration on NASA's Space Place website.

+ Expand image (top)