Defence Space & Missile Defence: Golden Dome and the SDA Architecture

Golden Dome for America is the US programme, ordered by executive order in January 2025, to defend the homeland against ballistic, hypersonic and cruise missiles and other aerial attacks. It combines space-based sensors, a space data network, ground and sea interceptors and possibly interceptors in orbit, run by a direct-reporting programme manager, General Michael Guetlein.

It depends on what is built. The Department's estimate for its objective architecture is $185 billion of acquisition out to about 2035. The CBO estimated about $1.2 trillion over 20 years for an architecture built from the executive order, including a large space-based interceptor layer. AEI's six illustrative architectures run from $471 billion to about $3.6 trillion over 20 years.

Because it prices a different system over a longer period. The CBO covers 20 years of development, deployment, replacement and operation, assumes full US coverage and includes several thousand space-based interceptors with five-year lives, which make up about 70% of its acquisition cost. The Department's $185 billion is acquisition only, to about 2035, and the Department has not committed to a large interceptor layer.

Not as of 21 October 2026. The FY2027 request is about $17.5 billion, but only about $400 million is in the base budget; the rest depends on a second reconciliation law that has not passed. Golden Dome has no FY2026 appropriation, so a continuing resolution provides nothing for it.

Small satellites that would destroy missiles during boost phase or midcourse. Because satellites in low orbit move constantly, a constellation needs a hundred or more interceptors for each one within reach of a launch. Twelve companies hold prototype agreements with a $3.2 billion ceiling, aimed at an initial capability in 2028, but the programme's director has said boost-phase interceptors may not make the final architecture.

A constellation of missile-tracking satellites in low Earth orbit bought in two-year tranches from several manufacturers on fixed-price terms. Tranche 3 bought 72 satellites for about $3.5 billion (about $49 million each) for launch in FY2029, and an accelerated tranche bought 36 more for about $1.75 billion, ready for launch in 2028.

SpaceX holds the data-network backbone ($2.29 billion), the first space-based moving-target-indication award ($4.16 billion), an interceptor prototype slot and the largest share of national security launch. Lockheed Martin, L3Harris, Northrop Grumman, Rocket Lab and Sierra Space build tracking satellites; Lockheed builds the Next Generation Interceptor; ULA and Blue Origin share national security launch.

The programme plans an initial capability in 2028, tied to the accelerated tracking satellites, the first moving-target-indication satellites and interceptor prototypes. The full objective architecture extends to around 2035. Funding for FY2027 and the FY2028 decision on interceptors will determine whether those dates hold.

Building secure communications and reconnaissance first. The EU's IRIS² constellation was expanded in August 2026 to 348 satellites, including a 66-satellite defence and security layer, at an estimated €15.6 billion with first launches by 2029, and the EU's SAFE programme lends €150 billion for defence procurement. Germany has committed about €35 billion to space security by 2030, France more than €10 billion and the United Kingdom £7.8 billion of space spending to 2030; NATO's HALO initiative aims to link allied satellites for communications and missile tracking.

That interceptor magazines run out before sensors do. In the 2026 Iran war the United States and its partners intercepted more than 1,500 ballistic missiles, and the CBO estimates the United States used between one-half and two-thirds of its inventory of certain interceptors, with at least five years needed to rebuild. Ukraine shows that cheap threats must be defeated cheaply and that attackers adapt their missiles within months.

Not yet. Europe has no missile-warning satellites and relies on US data through NATO. France and Germany launched the JEWEL early-warning initiative in October 2025, targeting 2030 for its geostationary satellites, building on the EU-funded ODIN'S EYE studies. Germany fielded Israel's Arrow 3 interceptor in December 2025; a European hypersonic interceptor is not expected before about 2035.

Both call it destabilising and are expected to answer with more and more varied missiles rather than a matching shield. China is on course for more than 1,000 nuclear warheads by 2030, launched 91 orbital missions in 2025 and operates about 167 Yaogan reconnaissance satellites. Russia has fielded weapons designed to evade missile defence, parks inspector satellites near US satellites and is assessed to be developing a nuclear anti-satellite weapon.

It is the ally closest to it. Japan pays about a third of the US-Japanese Glide Phase Interceptor and builds half of it, hosts US space-surveillance sensors on its QZSS navigation satellites, and plans satellites to track hypersonic glide vehicles. It is the most likely ally to add tracking sensors to the architecture rather than only consume US data.

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