I’m the one that clears Supernovas for my Council.
This is a source of much confusion: The person who works with, and signs off, is a Supernova MENTOR. To have this position the adult must have been approved BEFORE they work with youth, either by the STEM Committee, if there is one, or, by the Advancement Committee. The requirements for the Mentor position include a STEM education AND experience.
Nova Counselors sign off Nova awards, but not Supernovas.
Now, for the awards.
There is a difference between the Nova and Supernova. The Nova is an introductory activity, and gets a patch and subsequent pins. The Supernova is designed to be much more intensive, and gets a medal.
Unfortunately, at the Pack level the Novas are not required to earn the Supernovas. They are “highly recommended” but not bothered with by many. At the Scout level the Novas are required as part of the Supernovas. But you are asking about the Pack level awards.
The Alvarez is for Cubs and can be done over the two years of Wolf and Bear. Townes is for the years covering Webelos and AOL. Both awards are inclusive of the respective time periods. Look at National’s STEM pages for what is required. We have a few in my Council who have earned both Alvarez and Townes. It’s not too common.
What you can’t do is have something done during Bear and have it count for Townes. Nothing done by a Tiger counts.
The awards are not dependent on each other. Both are awarded a medal and a bronze bar. Neither award carries over to Scouts. That is, the medals and bars earned while in a Pack are not worn on the Scout uniform.
The Pack level not being dependent on each other is not the same as at the Troop level. At the Troop level the awards are earned in a sequence, Harris and then Edison.
Councils are finding there are many more Pack level awards than Troop level. In my Council, for the time the awards have been available, there have been about 120 Pack level awards as compared to 5 Troop level awards. It’s parents pushing rather than self directed Scouts. And, the Scout level are significantly more difficult. The first one is arguably harder than Star.