EOSS-358 & 359 EPIC Littleton & Colorado Space Grant Consortium Flight - Recap

Summary: Two balloons were launched on Saturday, May 4 from Deer Trail Colorado.

  • The first balloon, EOSS-358 was an Exempt Payload string under a 1500g balloon carrying Student-built DemoSats from Colorado Space Grant Consortium schools. It reached an altitude of 89,485 feet and landed at 39.819, -102.984, 13.5 miles northeast of Anton, Colorado.
  • The second balloon, EOSS-359, was a Non-exempt payload string under a 3000g balloon carrying BalloonSats built by Littleton EPIC program students. It reached an altitude of 101,911 feet and landed at 39.78063, -103.16237, 4.0 miles northeast of Anton, Colorado.

More summary information to follow.

Link for EOSS mileage reimbursement  https://forms.gle/qJjy47iTHF5ywDPJ6

Original Announcement: 
  • 05-02-2024Payload Plans Rev D uploaded to this website
  • 04-28-2024Payload Plans Rev C uploaded to this website
  • 04-27-2024Payload Plans Rev B uploaded to this website
  • 03-05-2024Payload Plans Rev A uploaded to this website

Flight Predictions are available at: https://www.eoss.org/predict/

This is one 1500g balloon and one 3000g balloon or three 1500g balloons carrying student-built payloads from Littleton's EPIC Aerospace program and Colorado Space Grant Consortium from the flight that was canceled because of weather on April 20/21.

In case of clouds, the Heavy payload string will be split into two Lite balloons as follows:

Event Date: 
Saturday, May 4, 2024 - 00:00 to 23:45
Flight Coordinator: 
Launch Site: 

EOSS-359 Heavy

This is a 3000g balloon carrying student-built payloads for the Littleton EPIC Aeorspace program.

Balloon Type: 
Totes 3000g Latex
12 ft Rocketman with Remote Release Baker
144.905 MHzKC0D-1DF Beacon/Remote ReleaseSecondary Beacon
144.340 MHzAE0SS-3APRS/Digipeater Alias = "AEØSS-3"Primary Beacon, time slotted at 0:01 & 0:31
Payload Plan: 


This is a 1500g balloon carrying four Colorado Space Grant Consortium student-built payloads and possibly an imaging payload from COSGC.This is an Exempt (Lite) payload string.

Balloon Type: 
Totex 1500g Latex
12 ft Rocketman with Remote Release Charlie
146.710 MHzKCØD-3Remote Release/DFSecondary Beacon
144.340 MHzAEØSS-4APRS/Digi Alias = "VOYA"Primary Beacon Timeslotted 0:21 & 0:51
Payload Plan: 

EOSS Preflight Net @ 7 PM Mountain Time the preceding night:


The preflight net is hosted on the Fun Machine linked system https://www.we0fun.com/  

EchoLink *CANONCTY* conference and on the TGIF DMR Network Node: 1997 Talkgroup 815

Denver area Frequencies: 

    • 449.225 MHz (-5 MHz Offset, 141.3 Hz CTCSS) Mt Thorodin
    • 448.150 MHz (-5 MHz Offset, 141.3 Hz CTCSS) DIA
    • 449.975 Mhz (-5 MHz Offset, 100 Hz CTCSS) Westcreek
    • 447.525 MHz (-5 MHz Offset, 146.2 Hz CTCSS) Devils Head   

Back up Pre Flight Net Frequincies

        • 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:
        • 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
AlphaWAØGEH, KFØPCWMarty, Doug
BravoN6BAJeff D
CharlieKCØRPSJimFlight Coordinator
DeltaKØSCC, KØBRASephen, Doug GPost Launch
EchoKØNKK,KLØNLQ,Nancy,Anne,Post Launch
KiloKLØNLQ, KE0UWCGlennPost Launch
GolfNØNDMLarryPost Launch
Ground StationN2XGLJeff S, Randy
LimaKB0YRZChris, JenSaturday Only
MikeKE0GKIBernadette (CU)
NovemberKD0NKEKatie Rae (EPIC)
TR Breakfast: 
Limon I-HOP, 0600, Optional