MXER
Tether Boost Facilities for Orbit-to-Orbit Transfer:
Reducing the Cost of In-Space Propulsion
|
MXER
System Concept Animations
How does a rotating space tether catch and toss a spacecraft? How does electrodynamic
propulsion work? Click the images below to see Quicktime movies illustrating
how a MXER Tether Transport system will work [Animations produced by NASA/MSFC;
Grapple tests conducted by Tennesee Tech]
Background:
Momentum-Exchange Tethers
In a momentum-exchange tether
system, a long, thin, high-strength cable is deployed in orbit and set into
rotation around a central body. If the tether facility is placed in an elliptical
orbit and its rotation is timed so that the tether is oriented vertically
below the central body and swinging backwards when the facility reaches
perigee, then a grapple assembly located at the tether tip can rendezvous
with and capture a payload moving in a lower orbit, as illustrated in Figure
1. Half a rotation later, the tether can release the payload, tossing it
into a higher energy orbit. This concept is termed a momentum-exchange tether
because when the tether picks up and tosses the payload, it transfers some
of its orbital energy and momentum to the payload, resulting in a drop in
the tether facility’s apogee. [Learn more about MX
Tethers]
Electrodynamic
Reboost
In order for the tether facility to boost multiple payloads, it must have
the capability to restore its orbital energy and momentum after each payload
transfer operation. If the tether facility has a power supply, and a portion
of the tether contains conducting wire, then the power supply can drive
current along the tether so as to generate thrust through electro-dynamic
interactions with the Earth's magnetic field. By properly controlling
the
tether current during an orbit, the tether facility can reboost itself
to its original orbit, as illustrated in Figure 1. The tether facility
essentially
serves as a large "orbital energy battery," allowing solar energy
to be converted to orbital energy gradually over a long period of time
and
then rapidly transferred to the payload. [Learn more about ED
Tethers]
Net
Payoff of MXER Tether Boost Facilities
MXER Tether Boost Facilities can reduce the cost of not only in-space propulsion,
but also Earth-to-Orbit launch. For in-space propulsion applications, the
MXER tether can serve as a fully reusable upper stage. By eliminating the
need for each payload to have a dedicated upper stage vehicle, payloads
can be launched on much smaller and less expensive rockets. As an example,
a MXER tether designed to boost a 5 metric ton satellite from LEO to GTO
could reduce the launch vehicle required for that satellite from a $45M
Delta-II down to a $13M Dnepr 1 rocket, a roughly five-fold reduction in
launch costs.
Earth-to-Orbit Launch Assist
MXER Tether Boost Facilities can also enable dramatic cost reductions for ETO launch by catching payloads delivered into suborbital trajectories and then tossing them into orbit. [Learn more about Tether Launch Assist]
More
Information:
To learn more about TUI's MXER Tether Boost Facility systems, we invite
you to read some of our technical papers discussing our development of the
MXER technology:
For further
information on a space tether product customized for your needs,
please contact
TUI at information@tethers.com
For information on Momentum Exchange Propulsion for your mission, please | Contact TUI |
