Can scrapy step through a website by following "next" button
It sure can, there is multiple way:

Add SgmlLinkextractor to follow that next link.
Or make Request in your function, like yield(Request(url))

In your case url = erthdata.---.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=21&SID=d89sduisd&excludeEventConfig=ExcludeIfFromFullRecPage&page=1&doc=4&cacheurlFromRightClick=no
Can scrapy save a web page, follow the next button and save the next web page etc.,  in a series of search results? It always needs to follow the "next" button and nothing else.
This is the url (obfuscated) that links to the next page:
erthdata.---.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=21&SID=d89sduisd&excludeEventConfig=ExcludeIfFromFullRecPage&page=1&doc=4&cacheurlFromRightClick=no
Thanks
John