Thick cloud covers Venus completely, so no visible-light camera can see its surface. A team wants a global map of that surface. Which technology meets the goal?

Geologists want to date Martian rock using laboratory instruments that fill a room and cannot be flown. Which mission type gives them what they need?

Radio waves from a distant galaxy reach the ground, but one dish gives only a blurry radio picture. Astronomers want fine detail. Which technology meets that goal?

A team must examine several rock outcrops lying kilometers apart on the Martian surface, studying each one close up. Which technology meets that goal?

Scientists want temperature and cloud measurements that cover an entire planet and are repeated over several years. Which technology meets that goal?

Astronomers want to know which chemical elements are present in the outer layers of a distant star. Which instrument attached to a telescope gives them that?

An icy object lies far beyond Neptune. A spacecraft cannot carry enough fuel to slow down and stay there, but first close-up images are wanted. Which technology meets the goal?

An infrared space telescope carries a huge sunshield and is held below about -220 degrees Celsius. Which reason best explains that design choice?

A probe traveling to Jupiter and beyond carries a generator powered by decaying radioactive material rather than larger solar panels. Which reason best explains that choice?

Mars has an atmosphere roughly 1 percent as dense as Earth's. Landers there use a heat shield, then a parachute, and then rockets. Which reason best explains the rockets?

A radio observatory is built in a remote valley, and vehicles and cell phones are restricted for kilometers around it. Which reason best explains that choice?

Venus's surface is about 460 degrees Celsius under roughly 90 times Earth's air pressure. Landers sent there were built to finish their work within about two hours. Which reason best explains that?

Spacecraft that will land on Mars are cleaned and heat-treated to remove microbes before launch. Which reason best explains that requirement?

Large optical telescopes are built on high, dry mountain summits instead of near the cities that pay for them. Which reason best explains that choice?

A probe out near Neptune transmits with about 20 watts, and its signal reaches Earth extremely weak. What does this constraint require of the mission?

A space telescope that will work 1.5 million km from Earth needs a mirror 6.5 meters across, but no rocket fairing is that wide. What does this constraint force the design to do?

A crewed mission to Mars would last more than two years, with no chance of resupply after launch. What does this constraint require of the spacecraft?

A radio command to a spacecraft arriving at Saturn takes about 80 minutes to travel each way. What does this require during the engine burn that puts the craft into orbit?

Earth's atmosphere absorbs X-rays from space before they reach the ground. What does this force astronomers who want to study X-ray sources to do?

A mission must bring Martian rock back to Earth, so the collected samples have to leave the Martian surface again. What does this requirement force the mission to include?