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Mission Briefing: What Can Surveyor 7 See Change on Earth?

Grade 7 earth science: a satellite team compares landslides, lava, glaciers and rising land to explain changes at very different time and size scales.

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12 questions
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Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Sorting, Short answer

About this worksheet

What students practice

Students compare the rates and sizes of surface changes that take minutes, years and millions of years.
Students calculate average rates to explain how slow processes add up to large landforms.
Students use evidence to argue that both fast and slow processes shape Earth's surface.

How to use

Read the briefing aloud and make sure students understand pixel size and passes before they start. Allow calculators for the rate questions.

Curriculum

NGSS standard covered

MS-ESS2-2

Explain how geoscience processes at very different time and size scales have changed Earth's surface.

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Mission Briefing: What Can Surveyor 7 See Change on Earth?

Compare fast and slow surface changes with what a satellite can detect.

Four recent changes

Read the mission briefing and study Table 1. Then answer the questions.

Can Surveyor 7 See It Change?

1A space agency is planning Surveyor 7, a satellite that will watch Earth's surface from orbit. Before the design is final, the mission team must answer one question: which changes will it actually be able to see? At a briefing, mission geologist Dr. Ayesha Moreau reminded the team's student interns that Earth's surface changes at very different speeds and sizes. Some changes are over in minutes, and others take millions of years. Some cover one hillside, and others cover a whole region.

2Each pixel in a picture from Surveyor 7's camera covers a square 10 m on a side, so the camera cannot show anything smaller than about 10 m across. The satellite passes over the same place every 5 days. It also carries a radar that can tell whether the ground has moved up or down by 5 mm or more since an earlier pass, but the radar cannot show what the ground looks like.

3To test the design, the team studied four recent changes (Table 1). On Crag Mountain, a slope soaked by days of rain gave way in a landslide. On Marrow Island, a volcano poured lava into the sea, and the lava cooled into new land. The front of Ice Creek Glacier keeps melting back up its valley. Around Tern Bay, the land is still slowly rising because a thick ice sheet that once pressed it down melted about 10,000 years ago. Lines of rounded beach pebbles, left by waves long ago, now sit on hillsides high above the bay.

4The team also looked at three landforms that took much longer to build (Table 2). Marrow Island's volcano has grown up from the sea floor in many eruptions, with long quiet times between them, while rain and waves wear its rock away. Ice Creek's valley is U-shaped because glaciers filled it again and again during many ice ages, scraping its floor deeper each time.

Table 1. Four recent changes the team studied
Change	How long it took	Size of the change
Crag Mountain landslide	About 2 minutes	Scar 600 m long, 200 m wide
Marrow Island lava flow	About 3 months	1.2 km² of new land
Ice Creek Glacier front	Each year	Melts back about 30 m
Land around Tern Bay	Each year	Rises about 10 mm

Use Table 1 and paragraph 2.

Each year, the front of Ice Creek Glacier moves back by about how many of Surveyor 7's camera pixels? pixels

Which change in Table 1 could the radar measure within a year, but the camera could not show even in pictures taken years apart?

A. The rising land around Tern Bay
B. The landslide scar on Crag Mountain
C. The melting front of Ice Creek Glacier
D. The new lava land on Marrow Island

Suppose the land around Tern Bay keeps rising at the rate in Table 1. (1 m = 1,000 mm)

About how many years would it take the land to rise 1 m? years

Use paragraph 2 and Table 1. The camera shows a change only when it grows or moves by at least one 10 m pixel between two pictures. The lava flow added new land all through its 3 months, tens of thousands of square meters each week. Sort each change by the quickest way Surveyor 7 could detect it.

The Crag Mountain landslide scarThe Ice Creek Glacier front melting backThe land around Tern Bay risingThe new lava land on Marrow Island

Camera: two pictures 5 days apart	Camera: two pictures a year apart	Radar only (the camera cannot show it)

The rising land around Tern Bay covers a far larger area than the landslide scar. Why can the camera still show the landslide but not the rise?

A. The rising land lies under the sea, where the camera's pictures show just water.
B. The landslide changed the ground by hundreds of meters, but the land rises by millimeters.
C. The camera sees small areas, so a change 1,000 km wide is too big to fit in it.
D. The satellite passes over Tern Bay once a year, too seldom to catch the rise.

Landforms that took much longer

Use Table 2 and paragraph 4. Show your work on scrap paper.

Table 2. Three landforms and how long they took
Landform	Size	Time to form (years)
Marrow Island volcano	5,000 m tall from the sea floor	about 500,000
Ice Creek's U-shaped valley	1,000 m deep	about 2,000,000
Old beach lines at Tern Bay	Up to 150 m above the sea	about 10,000

5,000 m is 5,000,000 mm.

On average, the Marrow Island volcano grew about mm taller each year.

The recent lava flow built new land in only 3 months. Why is the volcano's average growth over 500,000 years so slow? Use paragraph 4.

A. Lava cools into new land only under the sea, so the island part stays the same.
B. The volcano grew quickly at first, then stopped erupting about 500,000 years ago.
C. Eruptions come only now and then, and between them rain and waves wear rock away.
D. Each eruption shrinks the volcano, because lava takes rock away from the island.

1,000 m is 1,000,000 mm.

On average, glaciers made Ice Creek's valley about mm deeper each year.

Use your answer to question 8. Suppose the valley keeps getting deeper at that average rate. One camera pixel is 10 m, which is 10,000 mm.

About how many years would the valley take to get deeper by the size of one pixel? years

10.

Which conclusion do Tables 1 and 2 support best?

A. The valley formed faster than the landslide scar, because the valley is deeper.
B. The land around Tern Bay stopped rising once the ice sheet had melted away.
C. The volcano and the valley each formed in one event that lasted a few minutes.
D. Small changes adding up over long times built the largest landforms here.

Planning the mission

Use the whole briefing and both tables.

11.

The team needs a satellite that can (1) show a new landslide as large as the Crag Mountain scar within a week after it happens and (2) measure each year how much the land around Tern Bay has risen. Which design meets both needs?

Table 3. Four satellite designs
Design	Pixel size (m)	Days between passes	Radar?
A	3	30	No
B	10	5	Yes
C	10	5	No
D	30	30	Yes

A. Design B
B. Design C
C. Design D
D. Design A

12.

A mission engineer says, "Surveyor 7 should only watch sudden events like landslides and eruptions. Slow changes are too small to matter for Earth's surface." Do you agree? Make a claim, use at least three numbers from the tables or your answers, and explain how processes at very different time and size scales have shaped the surface.