How about an orbiting tether about 628 kilometers long? It rotates (revolves) once per hour, so the end passes within about 50 kilometers of the ground while the other end is at an altitude of 678 kilometers. A hypersonic airplane attaches the payload at an altitude of about 51 kilometers, 30 minutes later the pay load is released at an altitude of about 678 kilometers. The circumference of the tip travel is 2000 kilometers, so the speed of the tip is 2000 kilometers per hour, add the speed of rotation (revolving) of Earth's equator = about 1600 kilometers per hour subtract the orbital speed of about 28,000 kilometers per hour = -24,400 kilometers per hour = the required speed of the hypersonic airplane. The minus sign has little or no meaning. The release speed is the sum = 31,600 kilometers per hour, so the pay load can go anywhere in the inner solar system, except Mercury and the Sun with a minor mid course correction. So a sling shot maneuver around Jupiter is possible, allowing anywhere in the solar system.
The tether strength requirements are moderate, unless we increase the rotational speed, which decreases the hypersonic airplane speed. Retiring ICBMs = intercontinental ballistic missiles can be modified to attach small pay loads, so we can test the concept without building the hypersonic airplane. There are some more details: 1 We need to reduce the jerk which occurs shortly after attachment, to avoid breaking the tether 2 The tether will be a lazy S instead of straight due to air resistance at 50 kilometers, but the payload and the air resistance will stretch the tether. These tend to cancel. 3 The lift and air resistance are not free, so we will need to restore the 2000 kilometers per hour and circularize the orbit after a few payload lifts. 4 Up to 48 payloads per day can be lifted. 5 The orbit can be semi-polar allowing easy access by most of the nations of Earth and a wide range of throw directions for the payload. 6 The tether will have stretch transients which can aggravate or help the attachment and the throw accuracy. 7 Making the tether longer reduces air resistance and the speed of the hypersonic airplane, but initial cost rises rapidly with length. 8 This concept was published in an old Analog perhaps 20 years ago. 9 An Edwards type climber should travel the tether to repair damage by space junk, atomic oxygen and micro meteorites. Neil editited to add (revolves)
The tether strength requirements are moderate, unless we increase the rotational speed, which decreases the hypersonic airplane speed. Retiring ICBMs = intercontinental ballistic missiles can be modified to attach small pay loads, so we can test the concept without building the hypersonic airplane. There are some more details: 1 We need to reduce the jerk which occurs shortly after attachment, to avoid breaking the tether 2 The tether will be a lazy S instead of straight due to air resistance at 50 kilometers, but the payload and the air resistance will stretch the tether. These tend to cancel. 3 The lift and air resistance are not free, so we will need to restore the 2000 kilometers per hour and circularize the orbit after a few payload lifts. 4 Up to 48 payloads per day can be lifted. 5 The orbit can be semi-polar allowing easy access by most of the nations of Earth and a wide range of throw directions for the payload. 6 The tether will have stretch transients which can aggravate or help the attachment and the throw accuracy. 7 Making the tether longer reduces air resistance and the speed of the hypersonic airplane, but initial cost rises rapidly with length. 8 This concept was published in an old Analog perhaps 20 years ago. 9 An Edwards type climber should travel the tether to repair damage by space junk, atomic oxygen and micro meteorites. Neil editited to add (revolves)
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