Editing STS-51-F (section)

=== Other payloads ===
The Plasma Diagnostics Package (PDP), which had been previously flown on [[STS-3]], made its return on the mission, and was part of a set of plasma physics experiments designed to study the Earth's [[ionosphere]]. During the third day of the mission, it was grappled out of the payload bay by the Remote Manipulator System ([[Canadarm]]) and released for six hours.<ref name=report>{{citation-attribution|1={{cite web|title=STS-51F National Space Transportation System Mission Report|url=https://www.scribd.com/doc/52621059/STS-51F-National-Space-Transportation-System-Mission-Report|publisher=NASA Lyndon B. Johnson Space Center|access-date=March 1, 2014|page=2|date=September 1985}} }}</ref> During this time, ''Challenger'' maneuvered around the PDP as part of a targeted proximity operations exercise. The PDP was successfully grappled by the Canadarm and returned to the payload bay at the beginning of the fourth day of the mission.<ref name=report/>

In a heavily publicized marketing experiment, astronauts aboard STS-51-F drank [[Soft drink|carbonated beverage]]s from specially designed cans from [[Cola wars|Cola Wars]] competitors [[Coca-Cola]] and [[Pepsi]].<ref>{{cite web|last=Pearlman|first=Robert|title=A Brief History of Space Marketing|url=http://www.space.com/news/spaceagencies/space_market_010531-1.html|publisher=Space.com|access-date=March 24, 2014|archive-url=https://web.archive.org/web/20090214131154/http://space.com/news/spaceagencies/space_market_010531-1.html|archive-date=February 14, 2009|date=May 31, 2001}}</ref> According to Acton, after Coke developed its experimental dispenser for an earlier shuttle flight, Pepsi insisted to American president [[Ronald Reagan]] that Coke should not be the first cola in space. The experiment was delayed until Pepsi could develop its own system, and the two companies' products were assigned to STS-51-F.{{r|as20101118}}

Blue Team tested Coke, and Red Team tested Pepsi. As part of the experiment, each team was photographed with the cola logo. Acton said that while the sophisticated Coke system "dispensed soda kind of like what we're used to drinking on Earth", the Pepsi can was a [[shaving cream]] can with the Pepsi logo on a paper wrapper, which "dispensed soda filled with bubbles" that was "not very drinkable".<ref name="as20101118">{{cite magazine|date=November 18, 2010|title=Loren Acton: The Coke and Pepsi Flight|url=https://www.airspacemag.com/multimedia/in-the-age-of-spaceplanes-72344760/?page=3|magazine=[[Air & Space/Smithsonian]] |publisher=[[Smithsonian Institution]] |archive-url=https://web.archive.org/web/20220412162901/https://www.smithsonianmag.com/air-space-magazine/in-the-age-of-spaceplanes-72344760/ |archive-date=April 12, 2022 |url-status=live }}</ref> Acton said that when he gives speeches in schools, audiences are much more interested in hearing about the cola experiment than in [[solar physics]].{{r|as20101118}} Post-flight, the astronauts revealed that they preferred [[Tang (beverage)|Tang]], in part because it could be mixed on-orbit with existing chilled-water supplies, whereas there was no dedicated refrigeration equipment on board to chill the cans, which also [[fizz]]ed excessively in [[Micro-g environment|microgravity]].

In an experiment during the mission, thruster rockets were fired at a point over [[Tasmania]] and also above [[Boston]] to create two "holes" – plasma depletion regions – in the ionosphere. A worldwide group of [[Geophysics|geophysicists]] collaborated with the observations made from Spacelab 2.<ref>{{cite web|url=http://harveycohen.net/essex/index.htm|title=Elizabeth A. Essex-Cohen Ionospheric Physics Papers |date=2007|access-date=February 5, 2022}}</ref>