(1) Test Prep Success in Space

Passage 1 A Success in Space by Cameron Keady

This article, written on 2014, describes the journey of a space probe to gather information about a comet.

(1) On November 12, a small probe helped scientists take a big step forward in space exploration. The probe, called the Philae lander, is the first spacecraft to set down on a comet. It will take photos and dig up samples from the comet's surface.

(2) The Philae lander is about the size of a washing machine. It dropped from the Rosetta spacecraft and landed on the comet Churyumov-Gerasimenko, also known as 67P. This mission could give researchers valuable information about the origins of our solar system and how it evolved.

A Long Journey

(3) Rosetta traveled for 10 years, and across 4 billion miles, to reach its destination. The craft was launched in 2004 by the European Space Agency to observe cornets. In 2011, Rosetta was powered down to conserve energy. Early this year, scientists brought it back to life to study 67P.

(4) Philae separated from Rosetta about 14 miles above the comet. At first, the lander failed to fire anchoring harpoons into the surface. It bounced three times before coming to a stop, said Stephan Ulamec, the lander project manager.

(5) The Philae lander will travel the surface of 67P and conduct a variety of scientific experiments. It could reveal secrets about the makeup of comets, the formation of our solar system, and even the origins of life. Researchers consider comets the remains of the ancient solar system. Their contents are preserved in a deep freeze because they spend much of their time far away from the sun. "What we believe is that we will study the most primitive material in the solar system," says scientist Gerhard Schwehm. He served as Rosetta's mission manager at the ESA from 2011 until ins retirement earlier this year.

In the Dark

(6) Scientists have not yet been able to determine exactly where Philae landed. Based on the first images the lander has sent back, they believe it is partially in a shadow of a cliff. That could be a problem, because it would prevent the lander from, using its solar panels to collect energy from the sun. Currently, the scientists are updating their plans to get Philae out of the darkness.

(7 ) Though it took a decade to get to 67P, Philae's stay on the comet will be a short one. As soon as it landed, a 64-hour countdown began. When it ends, Philae's on-board battery will run down. But Rosetta all continue to travel with 67P, sending information about the comet back to Earth to as long as it can.

Passage 2 Comet probe may shed light on Earth's past by Ashley Yeager

(8) Comets are rubble left over from the birth of the solar system. By studying these hunks of rock, dust and ice, scientists hope to better understand the early history of the solar system—including Earth's early years. And never has the chance of doing this been better than on the comet under Philae's robotic feet.

(9) After a more than 10.5-year voyage, this robotic lander has just set down onto the surface of comet 67P/Churyumov-Gerasimenko. On November 12, the day it landed, Philae and its mother ship—the Rosetta spacecraft—were roughly 500 million kilometers (310 million miles) from Earth.

(10) Several spacecraft had spent a few hours observing comets from on high as they flew by these mega-boulders. But until Philae's landing, no mission had placed research instruments onto a comet. The robotic lander has already been sending back photos and probing the rock underfoot. Philae may even get to observe gases or, other matter emerging from underground as the comet heats to scorching temperatures. And it will get beastly hot within a few months as the comet's orbit swings it in close to the sun.

(11) For now, scientists are trying to figure out precisely where Philae set down. Problems with a thruster1 kept the lander from holding fast on its first try.

(12) Now, instead of being entirely in open space, as planned, the lander is flanked by what looks like a cliff. "We are not sure how far we are from the cliff, but we are in its shadow permanently,"' says Jean-Pierre Bibring. A scientist at the Universite Paris Sud in Orsay, France, he spoke at a media briefing on November 13.

(13) The lander also is not sitting perfectly on all three legs, he noted. It is almost vertical, with two feet on the ground and one in open space.

(14) Sitting in a cliff's shadow also means the lander's solar panels will get less sunlight than mission scientists had expected. The early data suggest that the lands is getting lust 1.5 hours of sunlight per day. That is far less than the six to seven hours it would have gotten if it had landed exactly on target —which it did. At first.

(15) On that first touchdown, Philae hit the bull's—eye. But the lander didn't stick its landing. Instead, it bounced twice. In between the first and second touchdown, the lander shot a kilometer up into space. In fact, it caught almost two hours of air time before it hit 67P again. The next bounce sent it 20 meters into the air for a 7 minute leap. Researchers are now trying to identify precisely where the lander now sits.

(16) But Philae isn't the only science center studying the comet. Its mother ship, Rosetta, arrived at 67P on August 6, 2014. Immediately, that spacecraft began orbiting the comet and snapping pictures. Rosetta plans to stay with the relatively tiny celestial rock until at least December 2015. Scientists are hoping that throughout, Rosetta will be able to send back photos.​

1thruster: engine on a spacecraft that controls when and how fast it flies