Artist conception of the Defense Support Program satellite Northrop Grumman Corporation

When the only video evidence of a plane crash is shot after the smoke is filling the sky, how do you go about piecing the tragedy together, let alone determining it was brought down by a missile and what could have fired it?

The investigation into the crash of Malaysia Airlines flight MH17 began long before salvage teams recovered the first black box recorder in the conflict-ridden region of East Ukraine. And with reports emerging from news agency Interfax that Russian separatists plan to hand the recorder over to the Russian interior, the impartiality of information when it is released to investigators is already coming under question. But other, external methods have already determined a great deal about the final moments of MH17.


The most important of which, coming only hours after the crash, was the lofty claim by Ukrainian and US intelligence officials that the plane was shot down by a surface-to-air missile (SAM). Who fired the missile is sure to be a matter of great political importance over the coming days and weeks, with the prospect of international intervention looming in an already tense situation.

To make such a claim before the dust had even settled would require quite the metaphorical ace up the sleeve, but in America's case the Cold War has armed them with plenty of cards.

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The US Air Force's Defense Support Program (DSP) operates a web of satellites positioned around the Earth that act as an early warning system for weapons launches, including intercontinental ballistic missiles and spacecraft. Using infrared cameras, they are capable of detecting even smaller heat signatures -- such as launch blasts and booster plumes -- proving their usefulness in the first Iraq invasion, detecting the launches of Scud missiles and providing evacuation warnings to civilian and military targets alike. These satellites form part of the larger field of Measurements and Signals Intelligence service (MASINT) operated by many national military and spy agencies, including the US Department of Defence.

Detecting the launch of a missile is as simple as watching for a white spot on an aerial shot, then tracking the missile's trajectory back to its launchpad. This, in theory, would make it easy to discover the weapon used. However, infra-red sensors are not the same as the high-resolution cameras that provide us with a detailed view of our own home on Google Earth, and without additional surveillance satellites trained on the area at the right time, that information would be lost. That is, without some lateral thinking, a practice the intelligence industry excels in.

Self-propelled "Buk-M2" surface-to-air missile system on a military exhibition at the Kapustin Yar missile range, Znamensk, Russia Leonidl/Wiki CC BY 3.0

The cruising altitude of MH17 was last recorded at 33,000ft (10,000m). Most man-portable air defence (or MANPAD) systems have an engagement range of around 20,000ft (6,000m), ruling out a small, one-man launch and a whole litany of "dumbfire" rockets.


Alternatives are narrowed down to smarter, radar-guided missiles or an air-to-air engagement. Since flight radar picked up no combat jets in the area, the only remaining theory is a medium-to-long-range SAM with radar guidance. This allows MASINT analysts to narrow their searches based on how these systems work.

Before a missile is launched, a strong radar beacon would be used to acquire the target. After a "lock on", the payload is sent on a rough trajectory to cross the path of the target. But during flight, a radar on the missile itself would need to begin transmitting in order to reacquire the target and adjust flight course. These "pulses" can be specific to certain models of missile, and certain missiles are specific to launch vehicles. By detecting the radar signature of the missile, MASINT can compare it to known frequencies, as well as other variables -- such as speed of the missile -- and identify the weapon.

In the case of MH17, this appears to have been a Soviet-made BUK-M2. The BUK launches missiles that travel at speeds of up to 3 mach (1,000 metres per second), easily capable of catching a commercial passenger jet travelling at 800 kilometres per hour. The BUK is used extensively on both sides of the border, and were responsible for the downing of 4 aircraft during the 2008 conflict in South Ossetia, Georgia. The vehicles involved in that incident were allegedly bought from Ukraine, who have their own units, however with the rebel appropriation of many of Ukraine's military vehicles over the past few months, it is unclear if any separatist groups have obtained one themselves.