1 00:00:00,000 --> 00:00:01,500 Hi, Dr. D. 2 00:00:01,500 --> 00:00:02,500 Hi, guys. 3 00:00:02,500 --> 00:00:05,000 Is that the terrarium that you mentioned on the phone? 4 00:00:05,000 --> 00:00:06,000 Yes, it is. 5 00:00:06,000 --> 00:00:09,000 A terrarium is a clear container filled with small plants. 6 00:00:09,000 --> 00:00:12,500 The plant is open to the atmosphere, but mine is going to be tightly closed. 7 00:00:12,500 --> 00:00:17,000 It's really tricky to maintain all the basic needs of plants after I close it up. 8 00:00:17,000 --> 00:00:19,500 We learned about the needs of humans and animals. 9 00:00:19,500 --> 00:00:23,000 They include water, shelter, food, and air. 10 00:00:23,000 --> 00:00:24,500 What are the basic needs of plants? 11 00:00:24,500 --> 00:00:26,000 I'm sure they need water. 12 00:00:26,000 --> 00:00:27,500 And they need food. 13 00:00:27,500 --> 00:00:31,000 That's right. The most basic food of plants is the carbon dioxide in the air. 14 00:00:31,000 --> 00:00:33,000 And plants also need sunlight. 15 00:00:33,000 --> 00:00:37,000 You bet. If my terrarium is going to be successful, it must meet all these needs. 16 00:00:37,000 --> 00:00:41,000 Hey, I understand you need some help in finding a model for a habitat for Mars. 17 00:00:41,000 --> 00:00:43,000 We're having a little trouble getting started. 18 00:00:43,000 --> 00:00:47,000 Well, the best place to get started is to understand your problem by gathering information. 19 00:00:47,000 --> 00:00:49,000 Do you mean like the scientific method? 20 00:00:49,000 --> 00:00:52,000 That's right. So what do you know about the atmosphere of Mars? 21 00:00:52,000 --> 00:00:56,000 We know that it's mostly made up of carbon dioxide and hardly any oxygen. 22 00:00:56,000 --> 00:01:00,500 That's right. And not only that, but the Martian atmosphere is much less dense than the Earth's atmosphere. 23 00:01:00,500 --> 00:01:04,500 So in addition to not having any oxygen to breathe, there's yet another difficulty. 24 00:01:04,500 --> 00:01:06,500 What do you mean? 25 00:01:06,500 --> 00:01:08,500 Let me show you with this vacuum pump. 26 00:01:10,500 --> 00:01:12,500 Here, touch this water. 27 00:01:12,500 --> 00:01:14,500 What does it feel like? 28 00:01:14,500 --> 00:01:17,500 It's warm, but it's not very hot. 29 00:01:17,500 --> 00:01:20,500 I'm going to put this water underneath the bell jar. 30 00:01:20,500 --> 00:01:23,500 And the vacuum pump is going to pull most of the air out of the bell jar. 31 00:01:23,500 --> 00:01:25,500 Let's see what happens. 32 00:01:26,500 --> 00:01:28,500 Wow, the water's starting to boil. 33 00:01:28,500 --> 00:01:30,500 Does that mean it's hot? 34 00:01:30,500 --> 00:01:32,500 Let's find out. 35 00:01:38,500 --> 00:01:40,500 It's even cooler than before. 36 00:01:40,500 --> 00:01:43,500 That's right. The water didn't boil because it was hotter. 37 00:01:43,500 --> 00:01:47,500 It turns out when the atmosphere is less dense, water will just boil at a much lower temperature. 38 00:01:47,500 --> 00:01:50,500 On Mars, you can have ice or water vapor. 39 00:01:50,500 --> 00:01:53,500 But any liquid water will simply boil away or freeze. 40 00:01:54,000 --> 00:01:57,000 I guess our habitat had better have a denser atmosphere than Mars. 41 00:01:57,000 --> 00:01:59,000 Thanks, Dr. D. 42 00:01:59,000 --> 00:02:04,000 Oh, and by the way, I'm concerned about why the fish are missing from my favorite fishing spot. 43 00:02:04,000 --> 00:02:06,000 Maybe you should have the water tested. 44 00:02:06,000 --> 00:02:09,000 I also want to contact Ranger Cortez at Sandy Bottom Park. 45 00:02:09,000 --> 00:02:11,000 He may be able to help you. 46 00:02:11,000 --> 00:02:13,000 Thanks, Dr. D. Bye!