What kind of missions are US surplus ICBM's capable of launching?

Question

It has been proposed that the US military should repurpose suborbital, nuclear weapons carrying, intercontinental ballistic missiles for civil use, like Russia and Ukraine has done since decades. How many ICBM's would this concern? And what kinds of civil mission profiles would they be capable of? Aren't they overkill for use as sounding rockets? What other suborbital use could come in question? What payload could they launch to LEO? Could they resupply the Space Station? How much could they put in Lunar orbit?

Are they more valuable for civil purposes if they are reconstructed, maybe even used as solid strap on boostes on a liquid fuel orbital launcher? And why do they become "surplus"? Disarmament or aging?

Answer 1

This is actually a bit tricky, and relates to one of the basic tenants of the space race. The United States made small, accurate weapons, the USSR made large, less accurate weapons. Because the USSRs weapons were larger, and therefore heavier, it required heavier missiles to launch them, and thus they have the mass to achieve orbit if required, while the US's fell short.

There is exactly 1 long range US ballistic missile that is currently operational, the Minuteman. The speed which Wikipedia lists is 7 km/s. Orbital speed is about 7.8 km/s, so the speed is very close to the minimum required to achieve orbit. Estimated payload mass is ~350-400 kg. Thus, it might be possible to get a very small payload, on the order of 200 kg, in to orbit, especially if a fourth stage was introduced to give the required ~1 km/s delta v required to obtain orbit (Including the fact that a very low orbit isn't desired typically). That would be in LEO.

It turns out that modified Peacekeeper missiles have been retrofitted for orbital missions, by the program of Minotaur, which can carry up to 1700 kg, by adding additional stages and other modifications. These are highly modified, however, the most significant component of reuse being the solid rocket motors.

For comparison, the DNEPR-1 rocket, the most commonly used Russian ICBM turned to rocket, has a payload of about 4500 kg in to LEO. It has some uses, but is still a very small payload, it could lift a very small ISS supply mission, but not much beyond that. The ISS payload is listed at only 3200 kg.

Answer 2

The Trident D5 appears to have just enough impulse to reach orbit without its normal payload.

This summary, and its daughter pages for each stage provide enough information to determine that whilst the whole missile is 59 tonnes the mass devoted to items other than the three solid stages is nearly 6 tonnes. Whilst the payload is given as 1.6 tonnes I suspect that is a narrow definition of payload. This link describes a "mission dedicated" Equipment Section that could well account for the difference.

Subjective moment: I don't believe that the whole of that 6 tonnes would be necessary for a small launch vehicle for the normal necessities of modern avionics and a fairing. If you assume 500kg instead and a very poor Isp of 250s for the solids then the delta-V comes up as 9.8km/s.

So, a very small microsat class payload might be possible.

The data I used:

First stage:

Gross mass: 39,100 kg. Unfuelled mass: 2,242 kg.

Second stage:

Gross mass: 11,800 kg. Unfuelled mass: 790 kg.

Third stage:

Gross mass: 2,200 kg. Unfuelled mass: 159 kg.

Assumed Isp = 250s, a browse through wiki suggest it could be much better. Assumed other deadweight - 500kg.