While astronauts in space get to do many exciting things, they miss out on ordinary things that we all take for granted--being able to walk on firm ground, hanging out with family and digging into a slice of hot steaming pizza. Though not much can be done about the first two things, there may soon be a solution to the third one, thanks to this cool 3-D pizza printer! About a year ago, NASA offered $125 ,000 to Anjan Contractor, a 3-D technology expert, to build a device   that would allow astronauts to make pizza on demand. The mechanical engineer promised that his invention would produce pies in large quantities that looked, tasted and even smelled like pizza made in common ovens. Late last year, the engineer presented a video of his first prototype   that begins by creating a single slice of dough   that is cooked and printed at the same time. Then comes the tomato "sauce" -- a mix of tomato powder, oil and water and finally, a protein slice that resembles cheese. While the video doesn't show the baking process, the inventor says that once the pizza is printed, it can be ready to be consumed in 7 seconds. While the pie in the video looks delicious enough to attract any pizza lover, Anjan Contractor is far from ready for astronauts. That's because he still has to find a solution to make the food container in the printer last for 30 years. Though that may sound unrealistic, actually it is not. Anjan Contractor believes that the only way that is possible is that the water is removed from all the ingredients   and then they are reduced to the powder form. This, as you can imagine, will not be so easy. But, while the printer may not be ready for space, it certainly looks ready enough for people on earth. Hopefully, NASA and Contractor will consider selling it to those not fortunate enough to go to Mars! Why does the author mention the things that astronauts in space cannot do?
To ask us not to take common things for granted. To show they live a difficult life there. To show their life is boring in space. To introduce the topic of the text.