Finding NASA Information with Search
How does search find what we're looking for?
Search engines are designed to look at individual words on a page. They don't try to make any guesses as to what the Web site is about. Still, there are times when we have amazingly effective searches... how does that happen? The algorithms written to search and rank pages are very complex. For discussion purposes we will look at just a few specific functions. When search engines look at the words on a page, they look at things such as the number of times specific words appear, and where the words appear. The more times a word appears, the higher the search engine will rank that page for that word. The placement of a word in the page can also be very important. Is it used as the subject of many sentences? Is it used in the headings? Is it part of the Web page address? These syntactical things make a difference when engines rank pages.
The NASA search engine uses the same search criteria described above. The engine looks at all of the public Web sites within NASA's domain and calculates words and their placement on the pages and in the Web address. Then, when you type in your keyword search term or phrase, the search engine looks through the pages and brings up those that fit the criteria you have set.
Interpreting NASA Search Results
Using the word Gravity as the keyword search term, let's interpret NASA's search returns page.
Screen capture of search results
What Does It All Mean?
Let's interpret what you find on the search returns page. On the search using gravity as the search phrase, there were 200 document returns, 4,274 hits, and 433,989 pages searched. This just gives you a general guideline of how popular the search terms are on NASA Web sites. Directly below that is your Prev and Next options, which allow you to quickly go to the Previous page of link returns or the Next page of link returns.
Next you'll find the links themselves, along with a brief description of what the page contains. You can also find out more by looking at the link information itself. You will see the title of the page or document in bolded letters, followed by a brief description underneath. Under the description is the Web address of the resource. To the right of the link is the ranking along with more search information. The links are always arranged with the highest match rates at the top, then go in order to the lower rankings. The percentages are based on different criteria set by the search engine as to how many times the word appears in the page, and where or how it appears, similar to the information on how search engines rank pages. The most important thing to remember is that the top return has a greater chance of having the information you're looking for versus the second return, and the second return has a higher probability of having useful information versus the third return and so on. However, the search logic is not infallible, so it's always helpful to look through a number of the links before doing another search.
The Start of a Successful Search
The first step to a successful search is to determine what type of information you are looking for. Are you looking for information that is very broad, very general in nature, or very specific? Determining what type of search you are doing will help you develop a more effective search strategy.
You're going to be doing a unit on Space Science and the universe in a few months. At this time however, you're not sure WHAT resources you are going to pull in for your class. This scenario portrays the need for a very broad type of search. Since you're not sure yet what direction you want to take with the unit, you will probably want to gather as much information on what is available for you to use.
Now let's say you've done more research on the universe theme and have decided to spend some time on both the Hubble Space Telescope and the Chandra X-Ray Observatory satellites. Looking for information on these specific satellites is an example of a more narrowed and defined type of search. You know to a greater extent what you're looking for and can be more specific when doing your searches, yet you still have a number of things to research about the satellites themselves.
But what if what you're searching for is one piece of information, or the answer to a very specific question? What if your students wanted to find out how a wind tunnel works, or how the Space Shuttles got their names? These types of questions are very specific and defined and would have more definitive answers than the searches discussed above.
As you see by the three scenarios above, deciding whether your search is broad-based, more narrow and defined, or very specific will help you decide how to go about searching.
Deciding on the Best Approach
Once you've determined whether your search is broad or narrow, you can determine which approach will be the most effective. Will you search using a phrase or a string of search words, or will you use only one keyword term? Deciding on which sentence, keywords, or phrases to begin your search can determine how successful you will be. The more unique you can make your word or phrase, the better the chance of having relevant links returned. For your more narrow searches, you can actually type in the sentence or question you're looking to answer. The NASA search engine accepts questions written in general English, so both teachers and students can find answers to their questions.
Whether your search is broad or narrow, you might consider making a list of items you could search for or by, as well as a list of questions or phrases that might help narrow your search. Explore the different avenues that could lead you to your final goal. After you've planned out your best route(s), knowing some of the basic rules for doing searches will help you narrow your list of return links. By filling out the search field using a few handy tools, you can "weed out" undesirable links and save a lot of time and frustration.
NASA's Search Engine Syntax
Most search engines have tips that help make your search more precise and less time-consuming. NASA's Web site gives helpful tips in the gray box on the top right hand side of the screen, and gives you more information at the address below.
Your best option is to search with just one keyword if possible. The more unique the word is, the better the chances of you getting relevant hits. If you want exactly what you've typed in a phrase included, put the entire phrase in quotation marks. Don't forget to use the Advanced Search and the Popular Search Items links on the search pages when you want to delve further into the search results from another search.
Searching for Images and Multimedia
NASA also has some specialized search features to help you find images, NASA TV, and multimedia resources for you and your classroom. There's also a page that allows you to quickly and easily locate those items that are considered popular search terms and topics.
The Web site below will help you if you're looking for images, aerospace multimedia, NASA TV information, or Astronaut photos of Earth.
Popular Search Items
Many of NASA's technical reports fall under the auspice of Public Domain and are therefore available to the public. The NASA Technical Reports Server is available at the Web address below.
Here at NASA, we use our search engine to help people find resources and information. With this search information and guidelines, your searching should now be easier and more successful than ever before.