National Aeronautics and Space Administration + en Espanol
+ For Educators
+ NASA Quest
+ Search Quest
 Find it at NASA
 Introduction Pre-Test Life Sciences at NASA Drosophila
 Flies in Space
 Immune System Scientific Method Video Gallery Post-Test



Scientific Method: Introduction

Scientists all over the world use a common process for performing their experiments. This process is called the scientific method. In the scientific method, researchers review background literature, state the problem, form a hypothesis, design and do the experiment, collect data, analyze it, and draw conclusions. Examine the chart below for more information about each step.

Step Description Example Image
Review background information Scientists look for research that has already been done on their topic to determine if they are duplicating a past experiment, doing something new, or building on a previous experiment. Much of the research can be done using the Internet. If I wanted to keep astronauts safe on long trips in space, I would review the research that NASA’s life scientists have already done. I would find that the immune system is affected in astronauts and that it is often studied in smaller animals like fruit flies.
Drosophila melanogaster, or common fruit fly, sitting on a piece of melon skin.
State the problem Once scientists have an idea of the research question they want to study, they state the problem. How does the space environment affect fruit flies’ immune systems?
A Drosophila melanogaster larva fluorescently labeled to visualize the nervous system.
Form a hypothesis A hypothesis is a statement of what the researcher thinks will happen in the experiment. It must be observable and testable. Since immune suppression leads to increased bacterial infections, fruit flies exposed to the space environment will be more susceptible to bacterial infections than fruit flies not exposed to the space environment.
Fly chambers in Experiment Research Module.
Design and do the experiment When designing the experiment, the researcher carefully controls as many variables as possible. In most experiments there is a control group and a treatment group. The two groups are as similar as possible, but the treatment group is the one that experiences the variable that you’re studying. In the Flies in Space experiment, scientists will perform a ground experiment with the same equipment, fruit fly food, procedures, temperature, and schedule as the flies in space. This is the control group. The experimental group is made up of the flies that travel on the space shuttle. The only difference between the two groups is whether or not they were in space. All of the flies will be exposed to bacteria on Earth after the space travel.
Doing an experiment during the Hyper-G high school team biology competition.
Collect and analyze data An important part of research is collecting data. After the data are collected, they are analyzed. This step often involves organizing data in charts and graphing it. In this experiment, data will be collected about how much bacteria the flies were exposed to, and the number of flies that showed negative effects from the bacteria.
Data collection during the Hyper-G high school team biology experiment.
Draw conclusions After the data are analyzed, scientists see if the results support their hypothesis. Even if the hypothesis is not correct, conclusions can still be made and significant knowledge gained. Depending on the data about how flies react to the bacteria, scientists will evaluate their hypothesis to determine if space travel affected the flies’ immune system.
A team of researchers looks on as a beaker of fruit flies is analyzed.


left arrow right arrow

 FirstGov  NASA
Editor: Carol Elland
NASA Official: B J Navarro
Last Updated: September 2006
+ Contact Us