Of all the possible sites to launch a stratospheric balloon, one could hardly think of the bottom of an iron mine as one of the most appropriate. However, at the end of the 50's decade the U.S. Air Force conducted several launches of these artifacts from the open pit of at least three different iron mines in the Cuyuna Range located on the outskirts of the village of Crosby, in northern Minnesota.

Launch of a ballloon from the Portsmouth Iron Mine

The balloon launches were directly related to manned flight programmes of the USAF and Navy, known as "Manhigh" and "Stratolab" and the main reason for choosing these sites lies in the form on which these balloons are launched: instead of using the common dynamic launch method they had used the vertical launch method, best suited to avoid excessive shocks at the payload during the launch. The walls of the mines pits formed a natural containment to prevent the balloon skin from damaging by strong surface winds in the critical phase of takeoff. Additionally, sometimes around the rim of the crater there was a lot of surplus material coming from the mine exploitation which offered even greater protection.

There was another place of similar characteristics and natural origin known as "Stratobowl" (located in South Dakota) that was used in the past for these launches but it was not appropriate because the dimensions of balloons used in the manned program largelly exceeded the height of its walls.

Thus, since July 1956 were carried out from the bottom of the Porstmouth Mine -and even twice from the neighborings Feigh and Mangan-Joan Mines- several balloon launches to conduct different tests, carriying from instrumented gondolas to a replica of the "Manhigh" capsule to be used in manned flights, with various types of animals inside it. These tests were vital to acquire the know-how necessary to accomplish the historic mission of the "MANHIGH II" flight which took place in August 19, 1957. Onboard the capsule was USAF Major David G. Simons who spend near 40 hours in the stratosphere, in near space conditions. After this historic landmark there were another flights including two other manned flights from the "StratoLab" navy programme, until the last one unmanned test held in October 1959, which closed a brilliant page of the history of the human access to space.

A year later, Porstmouth and the other mines of the Cuyuna Range would cease its activity and after a while abandoned. As the years go by the mines pits were filling with water, creating progresivelly a chain of crystal water lakes of great interest for tourists. This and other lakes have a generous amount of trout fish. In recent years a strong preservation and improvement policy lead to the grow of the zone as a vacation destination, creating the basic infrastructure to enable the development of water sports and also diving.

The former main balloon launch base is now the Portsmouth Mine Pit Lake and with its almost 425 feet is the deepest lake in the state of Minnesota.

Recently in August 2007, Crosby held the MANHIGH 50th anniversary celebration which included the presence of the pilot of the mission Dr. David Simons, the inauguration of an information kiosk at the very edge of the lake than half a century ago saw the balloon launch and a public exhibition of a 1:1 replica of the capsule used in the flight.

List of Balloons launched from Portsmouth Mine

DateHourFlight DurationExperimentPayload landing place or cause of the failure
7/11/1956 ---STRATOLAB--- No Data ---
7/23/1956 ---STRATOLAB--- No Data ---
8/6/1956 ---STRATOLAB--- No Data ---
8/20/1956 ---STRATOLAB--- No Data ---
9/18/195612:25 utc9 h 36 mMAIN PAYLOAD UNKNOWN + GEIGER COUNTER + IONIZATION CHAMBERRedwood Falls, Minnesota, US
11/13/1956 ---PAYLOAD UNKNOWN--- No Data ---
11/17/1956 ---PAYLOAD UNKNOWN--- No Data ---
12/2/1956 ---PAYLOAD UNKNOWN--- No Data ---
12/17/195619:55 cst2 h 12 mMANHIGH CAPSULE TRANSPORTING ANIMALSRice Lake, Winsconsin, US
8/13/1957 ---PAYLOAD UNKNOWN--- No Data ---
8/19/19579:22 cdt33 h 10 mMANHIGH II - (Simons)In an alfalfa field near Frederick, South Dakota, USA
5/15/1958 ---PAYLOAD UNKNOWN--- No Data ---
6/21/19585:36 cst---PHOTOMETERS--- No Data ---
6/21/19585:51 cst---PHOTOMETERS--- No Data ---
6/21/19585:21 cst---PHOTOMETERS--- No Data ---
6/21/19585:00 cst---PHOTOMETERS--- No Data ---
7/26/1958 34 h 30 mSTRATOLAB HIGH III - (Lewis - Ross)--- No Data ---
7/30/19587:03 cst1 hANIMAL CAPSULE (JIG-I)--- No Data ---
8/7/19585:55 cst1 hANIMAL CAPSULE (JIG-I)Balloon burst. Payload landed near Pine City, Minnesota, US
2/19/1959 7 h 30 mPAYLOAD UNKNOWNNear Marshall, Minnesota, US
5/8/1959 ---STRATOLAB--- No Data ---
6/2/1959 ---STRATOLAB--- No Data ---
6/20/1959 ---STRATOLAB--- No Data ---
9/17/1959 ---PAYLOAD UNKNOWN--- No Data ---
9/17/1959 ---PAYLOAD UNKNOWN--- No Data ---

List of Balloons launched from Mangan-Joan Mine

DateHourFlight DurationExperimentPayload landing place or cause of the failure
5/6/195820:01 CDT11 h 25 mSTRATOLAB LOW III - (Mikesell - Ross)Near Galena, Illinois, US

List of Balloons launched from Feigh Mine

DateHourFlight DurationExperimentPayload landing place or cause of the failure
10/18/1957 10 hSTRATOLAB HIGH II (Lewis - Ross)--- No Data ---

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