User:OleWanKenobi/sandbox/Hypervelocity Asteroid Intercept Vehicle

A Hypervelocity Asteroid Intercept Vehicle (HAIV) is a space missile concept, proposed by Bong Wie from Iowa State University in 2011, that uses a nuclear explosion to offset the course of a near-earth object(NEO). This concept utilizes a leader and a follower spacecraft whereas the leader spacecraft impacts with the NEO to create a crater where the follower spacecraft can detonate for an optimal explosion. Compared to other asteroid disruption methods like a gravity tractor, a solar sail, or a mass driver, which take several years to be effective, A HAIV can be effective in short time frames. A HAIV would be capable of disrupting NEOs with warning times of less than 30 days.

History
Bong Wie is currently the director of the Asteroid Research Deflection Center (ADRC) and the Space Systems and Controls Laboratory (SSCL) at Iowa State University. Wie's area of studies include Space Vehicle Dynamics and Control, Analysis and Design of Flight Control Systems for Advanced Launch Vehicles, Solar Sail Flight Control Systems Development, Singularity Escape/Avoidance Steering Logic Development for Control Moment Gyros, Mission Analysis and Design for Intercepting, Impacting, and Deflecting Near-Earth Asteroids, and Asteroid Deflection Using High-Energy and Low-Energy (Gravity-Tractor) Approaches. In 2011, Bong Wie concluded that the only thing that can effectively disrupt a large asteroid in a short time frame would be a nuclear explosion.

Construction
The construction of a HAIV involves a leading spacecraft and a following spacecraft:

Leader Spacecraft
The leader spacecraft is a kinetic impactor, where its destructive force comes from its high velocity impact with the NEO. It's purpose is to make initial impact with the NEO to create a crater for the following spacecraft to detonate moments later. The closer the nuclear explosion is to the center of mass of the asteroid the less force would be required to disrupt the asteroid. A subsurface detonation can increase the effectiveness of the explosion by a factor of 20 compared to surface detonations.

The leader spacecraft is equipped with imaging and detecting devices to track a NEO. The NEO is first detected by a medium resolution instrument (MRI, like the one used on the Deep Impact (spacecraft) mission) which transmits its information to a high resolution instrument (HRI) for more accurate targeting of the NEO.

Follower Spacecraft
The follower spacecraft contains a nuclear payload with the purpose of either destroying or disrupting the NEO. After the leader spacecraft has impacted, the follower spacecraft would then detonate inside the crater made by the leader spacecraft. More energy from the explosion would be transferred to the NEO if it detonates closer to the center of mass.

Since the leader spacecraft impacts the asteroid first, the follower spacecraft would be hit with debris and prematurely detonate the nuclear payload, especially at high velocities. To counteract this, a hypervelocity heat shield was proposed. The exact type of shield has not been determined but the proposed types are: flat cylinder, conical, spherical, and Ogive.

Proposed Mission Types
The proposal of HAIVs included three different mission types with varying budgets and nuclear explosive payloads:
 * Delta II - The Delta II launch vehicle has an estimated cost of $500m and contains a nuclear payload of 300kg that can produce about 300kt of force.
 * Delta IV M+ - The Delta IV M+ launch vehicle has an estimated cost of $1B and contains a nuclear payload of 1000kg that can produce about 1Mt of force.
 * Delta IV Heavy - The Delta IV Heavy launch vehicle has an estimated cost of $1.5B and contains a nuclear payload of 1500kg that can produce about 2Mt of force.

Terminal Phase
During the beginning of the terminal phase, the two spacecrafts separate but remain connected via a 10m boom. The boom transmits information from the leading spacecraft to the following spacecraft and acts as a fuse when the leader spacecraft makes contact with the NEO.

Projections
According to Bong Wie, the subsurface detonation improves the force of the explosion by a factor of 20. This allows for a HAIV to mitigate a 1000 ft wide asteroid with a warning time of 30 days. Fragments of the asteroid may still hit earth, but damages would be minimal in comparison to full impact of the asteroid.

Funding
Bong Wie's preliminary conceptual design was funded by NASA Institute for Advanced Concepts, but Wie will require more funding to go into the late stages of the development of a HAIV.