Full Ocean Depth Lander

Landers are versatile mechanical platforms used for carrying tools, instruments, scientific samples, imagery, measurements, etc. between the surface and the bottom of the sea. Landers usually consist of a metal frame shaped like a large square desk with a perforated top and tall mast in the middle that carries lightweight flotation at its top.

Landers are launched into the ocean with attached ballast weights that allow it to free-fall to the bottom. Depending on the depth, the descent to the seafloor could take up to several hours. At the end of each deployment, the ballast weights are released with a timer or acoustic signal and the lighter-than-water lander then ascends to the surface. Once on the surface, the lander’s antennas and bright color of the flotation foam make it easy to spot and recover the lander.

The Lander shall employ proven technologies and will be modular / reconfigurable to support missions for:

Communications gateways
Imaging
Fauna attraction

Fauna trapping
Water sampling
In-situ environment sensing

Configuration

The core components for the baseline lander have an air weight of 1295 lbs and a wet weight of 264 lbs.
The lander is divided into four systems to aid in the description of component groups. The items that are included in each system are as follows:

Core components – Lower platform that includes; the base frame, removable legs, lower mast, and release mechanism components and deck grating. The upper mast assembly includes: upper mast weldment, buoyancy foam module, foam mounting brackets and the lift bale. The instrumentation includes: acoustic release, ROV-Homer beacon, radio beacon, flasher beacon and all corresponding clamps and hardware.
Drop Weights – descent weight stack and ascent weight stack.
Ballast – added weight or buoyancy to ballast the system according to requirements.
Payload – all science payload, which may include niskin bottles and mounting brackets.

Science Payload

Payload is specified per dive. An air weight and displaced volume for all payload items must be calculated prior to each dive and entered in the attached weights & balance spreadsheet. Payload weight should be evenly distributed around the lander deck grating in order to minimize pitch and roll.

• The payload in water weight shall not exceed 200 lbs.
• The water weight of the lander system at the dive depth is not be less than 35 lbs.
• The net buoyancy of the lander system at the surface, post-dive, is not be less than 80 lbs.

Launch & Recovery

Launch and Recovery – the lander is suspended from A-frame during Launch and recovery.
Surfaced, Pre-dive and Post-dive – the lander is free floating in the water.
Vertical Velocity 30m/min.

Ballast

Ballast is determined by configuring either syntactic foam or ballast weights which shall be added to the lander to ballast the system to the required net buoyancy for post-dive.
Two additional syntactic foam blocks are provided as ballast options. Each block measures 4”x12”x24”, has an air weight of 31 lbs, a displaced volume of 0.73 ft3, and provides 15.5 lbs of buoyancy.

Releases

Acoustic release, commanded from ship or vehicle, for redundancy.
Manual release operable by vehicle for redundancy.
Galvanic dissolving release various duration.

Drop Weights

The ascent weight stack is added to the lander release mechanism and is used to add weight to the lander system to result in the required wet weight at dive. The number of weights in the ascent weight stack is adjusted to meet this requirement.
The descent weight stack is attached to the ascent weight stack through a wire tether. The recommended tether length is 20 meters. The descent weight stack is added to the lander system to facilitate descent to the sea floor. This stack will impact the seafloor first, thus reducing the ultimate descent rate and seafloor wet weight of the lander. The number of weights in the descent weight stack is adjusted to achieve the desired surfaced, pre-dive wet weight and resultant descent terminal velocity.