Does anyone have an idea of titles of either of these books?
“ I am looking for a Science Fiction book that I do not know the author's name or title of. I read this book in the early 2000's and can only remember the story. The book is set in the near future. Humans travel to the end of the solar system and discover that aliens inhabit all of the space around the solar system. These aliens are xenophobic and are the reason why no intelligent life has ever visited us. Once the aliens learn that humans exist they re-power their space ships to come into the solar system and kill all of mankind.
“A dead dragon somehow gets sent back in time and the people there have to make a vaccine and put it inside of a cave that can only be opened in the future with a the word "AIR". The dragons of the future keep dying from a mysterious sickness and no one can fix it. Somehow the people in the future find the cave and open it. Inside the cave is a classroom where they have to learn how to make the vaccine. It’s like a small classroom. They have to open the last room in order to save all the dragons. I believe I was in middle school when I read this, maybe 2002-2005. The book was amazing. I specifically remember a yellow dragon.”??