1) Many people know that garbage is a big problem on Earth. What many people don't know is that trash has become a problem in space too. Years of space travel have left tones of space junk” in orbit around the planet. 2) There are more than 22,000 pieces of junk in space around the earth. And these are just the items that we can see from earth. There are also millions of smaller pieces of junk that we can't see 3) To help reduce more space junk, countries around the world have agreed to limit the time their tools stay in space to 25 years. Each tool must be built to fall safely into the earth's atmosphere, or the gases that surround the earth. After that, in the upper parts of the atmosphere, it will burn up. 4) Scientists are suggesting different ways to clean up space junk. In England a metal object is being tested that can be sent into space and then pull the space junk back into the earth's atmosphere where it would burn up. The Germans have been planning a space mission with robots that would collect pieces of space trash and bring them back to Earth so that they can be safely destroyed. 5) "In our opinion the problem is very challenging, and it's quite urgent as well," said Marco Castronuovo, an Italian Space Agency researcher who is working to solve the problem.
Which word can we use to replace the words "as well" in paragraph (5)?