The FamilySearch.org website is a portal to a vast online collection of information about the early pioneers of Utah and other parts of the Western United States. Some members remember their pioneer ancestors each year around the 24th of July and then promptly forget them for the rest of the year. FamilySearch.org has a link to the Church History Library where many journals, diaries and other important documents are located. The list shown above is available for each registered user of the program on the Pioneer Ancestors page on FamilySearch.org. This is another of those pages located in the website that is buried and can only be found through a Google search for the terms "familysearch pioneers."
Once you sign into the website, you will see a list, like that above, showing some of your ancestors who are identified as pioneers. It should be pointed out from the list that most of the people listed had spouses and children who also crossed the Plains to Utah between 1847 and May 10, 1869, the time period considered as determining who was and who was not a pioneer. These seem to be missing from the list. It is possible that they simply limited the number of entries on the list to some arbitrary number.
However, lately, there has been a movement to include "pioneers" who join The Church of Jesus Christ of Latter-day Saints from all parts of the world and even in the present time. Here is a screenshot showing that part of the "pioneer" page that talks about these more modern pioneers.
If you view the Trail Stories you will find a wealth of information about the people in your ancestor's company. Here is a screen shot of the page for George Jarvis 1823-1913. Note the list of links to original documents and journals.
This is certainly a website worth exploring.