EOSS-376 and EOSS-377: DSST /Wheatridge HS - Recap

Submitted by Doug NØMM on Sat, 05/10/2025 - 22:57

May 10, 2025

Two balloons were launched and payloads recovered successfully.

EOSS-376, a 1500g latex balloon carrying an exempt payload of CubeSats for DSST Cedar High School students was launched from the Limon Softball Fields at 6:55 a.m. It reached an altitidue of 92500 feet before burst, and its parachute carried the payloads to landing near Colorado State Highway 71 and County Road 2K in Lincoln County, about 23 miles south of Limon, CO.

EOSS-377, a 3000g balloon carrying a non-exempt payload of 4 CubeSats (2 3U clusters and 2 single CubeSats), was launched at 7:14 a.m. and reached an altitude of almost 63000 feet before burst, significantly less than its predicted altitude of over 105,000 feert. Payloads were successfully recovered east of State Highway 71, a half mile north of CR 2K.

We appreciate the generosity of Mr. Fred Poss, whose family business, Poss Farms, owns much of the property for several miles around the landing sites of EOSS-376 and EOSS-377. EOSS could not complete is mission to give STEM students access to high-altitude balloon experiments without the cooperation and goodwill of owners of the property upon which our parachutes land.  

EOSS member mileage reimbursement submission here

Recap Gallery: 
Original Announcement: 

The Rocky Mountain Section of the American Institute of Aeronautics and Astronautics (AIAA-RMS) is sponsoring this launch day for the Denver Schools of Science and Technology (DSST) and Wheatridge High School, which will include two balloons: a 3000g latex balloon and a 1500g latex balloon. If weather conditions demand, we will launch three 1500 g latex balloons.

The balloons will carry CubeSats containing a variety of student experiments to altitudes approaching 100,000 feet. In addition to Wheatridge High School, three DSST high school campuses are represented in this launch: DSST Montview, DSST Cedar, and DSST Conservatory Green.  

Launch Time: First balloon: 06:45 MDT (12:45 UTC) Second: 7:05 a.m. MDT (13:05 UTC), and Third: 7:25 a.m. MDT (13:25 UDT)

Launch location: Limon Softball Fields, 50597 Colorado Highway 71 (about 3.5 miles south of Limon, CO) 

Flight Path Prediction: eoss.org/predict. Locate the flight number (e.g., EOSS-376) and scroll to the launch location (e.g., Limon). Choose 'GIF' for a map image of the predicted path.:

Live Tracking of Flight: track.eoss.org 

For EOSS Members

The EOSS participation form is available here: https://forms.office.com/r/dvFGCTnrXv. The summary spreadsheet is available here: EOSS Flight Day  May 10th, 2025.xlsx and will be available to you (sync'd to the submitted forms) if you are signed in to your EOSS Teams account.

Flight Coordinator: 
Doug Leber NØMM
Event Date: 
Saturday, May 10, 2025 - 00:00 to 23:45
Alt Launch Date: 
Sunday, May 11, 2025
Launch Site: 
Limon Softball Fields
Flights: 
Event Date: 
Saturday, May 10, 2025 - 22:30
FrequencyList: 

EOSS Preflight Net @ 7 PM Mountain Time the preceding night:
        •  449.225 MHz (-5 MHz Offset, 141.3 Hz CTCSS) Rocky Mountain Ham Radio (RMHAM) Repeater and EchoLink *CANONCTY* conference and the Fun Machine linked system
        • 146.940 MHz (-600 KHz Offset, 103.5 Hz CTCSS) Rocky Mountain Radio League (RMRL) Repeater if the RMHAM machine is down
        • 146.640 MHz (-600 KHz Offset, 100.0 Hz CTCSS) Denver Radio League (DRL) Repeater will serve as a backup to the backup repeater 

Flight Day:
Launch Site:
        • 446.050 MHz Simplex  
        (Note that some radios assume these are repeater frequencies and attempt to put a 5 MHz offset in the transmit frequency automatically)

Track & Recovery Operations:
        Repeaters:
        • 449.450 MHz (-5 MHz Offset, 103.5 Hz Tone) RMRL repeater

        Simplex Frequencies:
        • 446.100 MHz Balloon #1 Field Simplex 
        • 446.150 MHz Balloon #2 Field Simplex
        • 446.200 MHz Balloon #3 Field Simplex
        • 446.275 MHz Car to Car drive out Simplex
        (Note that some radios assume these are repeater frequencies and attempt to put a 5 MHz offset in the transmit frequency automatically)

Digital Mobile Radio (DMR):

The decision as to which talkgroup use will be made by the EOSS RF Coordinator on a per flight basis.

  • Rocky Mountain Wide Network – Talk Group 700 - Rocky Mountain Ham Radio has approval to the use "Wide" for flight operations.
  • Central Colorado Regional Network – Talk Group 720 - On occasion, EOSS may use the Central Colorado Regional Network (Talk Group 720).

        Legacy 2M Simplex Frequency (not generally used due to desense/interference issues with the 2M APRS packets)
        • 146.550 MHz Simplex

2M Direction Finding Frequencies:

  • 144.340
  • 144.360
  • 144.905
  • 145.535
  • 145.645
  • 145.710
  • 145.765

 

Tactical Calls: 
TacticalCall SignNameNotes