Thursday, 24 March 2011

The XM-7 Spider Program

From Weapons and technology

The XM-7 Spider program was established to develop alternatives to persistent antipersonnel landmine in Korea along the de-militarized zone. Spider is more of a “remote explosive device” than a typical fire-and-forget land mine. It is detonated by soldier command, and that soldier can even use non-lethal canisters if those have been loaded.

Unlike conventional land mines, the XM-7 Spider always has a known location, and can be safely recovered with ease and and readied for a new deployment if it has not been fired. If that isn’t possible for some reason, the units will deactivate after a set time period so they won’t become a future threat. The XM-7 is the successor to the Matrix system deployed in Iraq, and part of the USA’s Non-Self-Destructing Anti-Personnel Landmine Alternatives (NSD-A) program.

The XM-7 Spider system consists of up to 84 Munition Control Units (MCUs). They are set up by humans, unlike some land mines that are fired into place using artillery, mortars, or rockets. A tripwire container fires out 6 trip-wires when the device is activated by the human operator. As one might expect, each MCU can contain up to 6 reloadable canisters spaced around the device, each of which covers a 60 degree arc to create full 360 degree coverage. Payloads can be anything from Claymore-style steel balls or fragments, to non-lethal gasses or goo; ATK’s XM-7 data sheet even has a photo that shows an M18 Claymore adapter, which lets the Claymore’s wire plug into one of the MCU’s sockets.

The core MCU is powered by a replaceable battery, which can keep the device operational for at least 30 days. When an MCU is active, a GPS chip will report its location over an encrypted link to ensure that it doesn’t get lost. Once that battery fails, however, so does the MCU. This may seem like a poor design feature, but it’s a deliberate decision taken to ensure that XM-7s which are left behind in the fog of war don’t become future threats to human life.

All MCUs are controlled by a human-operated Remote Control Station (RCS), which is a standard rugged laptop computer, equipped with a touchscreen. If necessary, a signal repeater can extend communication range beyond 1 mile/ 1.5 km.

The operator can send a command to deactivate an MCU unit at an time. Recovery involves deactivation, followed by quick removal of the expended trip wire container and a check of the battery’s remaining power. The trip wire container, battery, and payload canisters are all designed to be replaced with ease in the field.

If the tripwires are touched while the unit is active, the MCU sends an encrypted signal to the operator. It’s up to the operator to decide what to do at that point, unless the XM-7 has been deliberately set in “battle override” mode that triggers the canisters automatically if a tripwire is touched.

The “battle override” feature would create an issue with the Mine Ban Treaty, but the U.S. is one of the major powers that has refused to sign that treaty. America has channeled its efforts into developing products like the more expensive but safer XM-7 instead.

A related product, the XM1100 Scorpion, applies many of the same technologies to create smart anti-tank mines.

The XM-7 Spider Program

The XM-7 spider systems is a joint venture between pre-eminent ammunition and explosives experts Alliant Techsystems Inc. (ATK) and Textron Systems Corp. ATK has been working hard to diversify more of its business toward precision weapons, and Textron also does some work in that area.

AP reported in 2004 that the Army intended to purchase 290,000 spider munitions as at cost of $513 million, after the system had incurred $135 million in development costs between 1999 – 2004. That would be divide up to about $2,250 per munition, which is expensive in comparison to alternatives. Subsequent events can raise that total further by changing system aspects, revealing engineering difficulties that must be corrected, or cutting the number bought so that the R&D dollars must be divided among a smaller set.

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