# JPL Open Source Rover: Building the Six-Wheel Mars Rover Design at Home

> The JPL Open Source Rover is a build-it-yourself, six-wheel rover modeled on the Mars rovers, assembled from consumer off-the-shelf parts for roughly $1600. It is a teaching platform and a rugged-terrain research base, not a kit you assemble in a weekend.

**nasa-jpl/open-source-rover** — A build-it-yourself, 6-wheel rover based on the rovers on Mars!

- Repository: https://github.com/nasa-jpl/open-source-rover
- Website: https://open-source-rover.readthedocs.io
- Stars: 9,678 · Forks: 1,510
- Language: HTML
- License: Apache-2.0
- Published: 2026-09-21 · Updated: 2026-09-21 · Language: en
- Canonical page: https://hysenlabs.com/projects/nasa-jpl-open-source-rover

## What the JPL Open Source Rover Actually Is

This is a set of published plans, not a product. The repository holds mechanical drawings, electrical documentation, a parts list, an expansion directory and a documentation site built with MkDocs. The README describes the rover as a scaled-down version of the six-wheel design JPL uses on Mars, designed entirely from consumer off-the-shelf parts. No metal machining is required for the base build, which is the single most important constraint in the whole project: every structural piece is bought, not fabricated.

The intended audience is explicit. The project is positioned as a teaching and learning experience for people who want to get into mechanical engineering, software, electronics or robotics, and the README states that no prior skills or knowledge is required. That claim deserves scrutiny. The skills section then lists soldering, electrical debugging, wiring and electrical safety as things where prior experience is not required but having someone who can help will save a lot of time. In practice this is a beginner-friendly design that still expects you to learn a bench skill or two along the way.

The rover is also pitched as a research platform for rugged terrain. Ten motors, an aluminum structure and a top speed of roughly 1.6 m/s, which the README compares to slow running and notes is subject to motor selection. Total cost lands near $1600, a figure the README itself compares to a TurtleBot 3 Waffle.

## Rocker-Bogie, Differential Pivot and Six-Wheel Ackerman Steering

The rover copies three driving mechanics from the Mars rovers, and they are worth understanding before you commit to the build because they are the reason the chassis is complicated.

Rocker-bogie suspension keeps all six wheels in contact with the ground while the rover climbs over obstacles. The rocker and bogie are linked arms, not springs, so the geometry does the work. A differential pivot then mechanically offloads weight from one side of the rover to the other while climbing. Together these two mechanisms mean the rover can tilt and articulate without a wheel losing traction, which is exactly the behavior you want on rock.

Steering is six-wheel Ackerman. The README describes it as the mechanism that governs where the wheels point and how fast each of them will move. That phrasing matters: this is not a simple servo-per-wheel arrangement. Steering angle and wheel speed are coupled, and cornering behavior depends on getting that relationship right.

The control architecture is a Raspberry Pi acting as the rover's brain. The README gives versatility, accessibility and simplicity as the reasons, plus the ability to add and upgrade your own modifications. Any method you can use to talk to a Raspberry Pi, including bluetooth, WiFi and USB devices, can be interfaced into the control system. That is a deliberately open-ended interface decision, and it means the software side of this project is a starting point rather than a finished stack.

## Installing the Documentation Site and Reading the Plans

The repository is not a software package you install on the rover. What you can install locally is the documentation site, which is built with MkDocs. The requirements.txt pins the toolchain, including mkdocs 1.6.1, mkdocs-same-dir and pymdown-extensions.

Create a virtual environment and install the pinned dependencies:

```bash
python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
```

The repository also carries a .readthedocs.yaml and an mkdocs.yml at the top level. Serve the site locally with:

```bash
mkdocs serve
```

MkDocs prints a local URL, normally port 8000, and you should see the same documentation that is published at open-source-rover.readthedocs.io. From there the useful entry points are the mechanical and electrical directories, the parts_list directory, and the expansion directory for add-ons. The examples directory holds a gallery of community builds, including earlier versions of the rover.

If you only want to look at the geometry, the README points to an online 3D model of the latest version hosted in OnShape, viewable in a browser without installing anything. That is the fastest way to judge whether you want to take on the mechanical assembly.

## Cost, Battery Life and the Discharge Warning

Budget near $1600 for parts, per the parts list the README links. Most of the mechanical assembly comes from GoBilda, and the README directs international builders to GoBilda's shipping policy, which is a quiet acknowledgement that sourcing is part of the project.

Drive time is quoted for a 7.2Ah battery with some driving on rough terrain: at least 3 hours. The README plots voltage, current draw and commanded velocity over time from a run on rocky terrain, and states that the rover powers down when voltage drops below 13 to 14V. You can extend runtime with a larger battery or by carrying a second battery to swap in.

The warning attached to that section is the one to take seriously. Discharging a LiPo battery too far drastically lowers its lifetime and can make it hard or impossible to recharge. The rover's own low-voltage power-down behavior is a partial protection, not a substitute for understanding your pack. If you have never managed lithium batteries, this is the part of the build where a mistake is expensive rather than merely annoying.

One spec to treat carefully: the roughly 1.6 m/s top speed is explicitly subject to motor selection. Do not plan around that number until you have chosen motors.

## Where the Open Source Rover Is the Wrong Choice

The honest limitation is that this is a project, not a shortcut. The README's own skills section lists soldering, wiring, electrical debugging and electrical safety as areas where help saves time. A build that needs those skills is not a first robotics project you finish in a weekend, regardless of the no prior skills claim in the introduction. The two statements sit in tension, and the skills section is the more accurate one.

Cost is the second constraint. At roughly $1600 in parts, the README compares the figure to a TurtleBot 3 Waffle. That is a real robot for a similar outlay, already assembled and supported by an existing software ecosystem. If your goal is to write navigation code rather than to build a chassis, the rover is the wrong tool.

Sourcing is the third. The mechanical assembly leans on a single vendor's catalog. If a part is out of stock or a revision changes, the plans do not automatically adapt.

Finally, the project is a hardware effort with a software component, not the reverse. The README notes that the hardware and electronics were designed with expansions like a head display and a robot arm in mind, which tells you the base rover is a platform to extend. If you want a finished, closed product with a support contract, look elsewhere.

## How It Compares to Sawppy and Other Open Rover Projects

The README acknowledges that other open-source, cheaper alternatives exist and characterizes them as slower, less strong and more fragile. Sawppy is the comparison people search for, and the difference is one of approach rather than quality.

Sawppy-style builds generally target a lower parts budget and use lighter, more accessible components. The JPL rover commits to an aluminum structure, ten motors and a $1600 parts list, and it buys its capability with that budget. The trade is straightforward: less money buys a rover that is easier to source and lighter to move, and more money buys a sturdier platform with the rocker-bogie geometry and differential pivot described in the README.

There is a second difference that matters more than the parts bill. The Open Source Rover is certified open source hardware, listed as OSHW certification US002551, and the plans trace back to a JPL design lineage. If provenance and a documented mechanical design are what you want, that is the argument for this project over a hobby alternative. If you want the cheapest path to a working six-wheel rover, the README's own framing tells you the cheaper options exist and what you give up by choosing them.

JPL and Caltech have no official affiliation with the community Slack group, which the README states plainly. The forum is run by members of the public, so treat answers there as community knowledge rather than vendor support.

## Licence and What Upgrades Cost You

The repository is licensed under Apache-2.0, and the LICENSE.txt file sits at the top level. For a hardware project, that licence covers the files in the repository. It does not cover the physical parts you buy, and it is not legal advice about your own derivative design. If you plan to sell a rover built from these plans, read the licence text and the OSHW certification terms yourself rather than assuming Apache-2.0 settles the question.

The upgrade cost is mostly in the expansion directory and in the README's note that the hardware and electronics were designed with a head display and robot arm in mind. Those expansions are the point of the design, but they are also where the README's machining caveat applies: no metal machining is required for the base rover, while optional expansions may call for a band saw or dremel, a drill press or hand drill, and filing and sanding. The base build is a bolt-together project. The interesting versions are not.

On maintenance, the last push to the repository was on 2026-09-03, and the most recent release is v4.0.0 from 2023-09-14, described as the v2 design. The README directs builders to check issues, pull requests and the Slack forum for upcoming changes. For a hardware project, that is the practical upgrade path: watch the repository and the community rather than expecting a versioned migration guide.

## Conclusion

Adopt the JPL Open Source Rover if you want a long mechanical and electronics build that ends in a platform you can program yourself, and you accept roughly $1600 in parts plus tools and soldering. Do not adopt it if you need a finished product, a kit with a single order number, or a rover you can drive the week it arrives. Before buying anything, verify the current parts list against GoBilda stock, confirm which hardware revision the mechanical and electrical directories describe, and read the battery discharge warning in the README.

## FAQ

### How much does the JPL Open Source Rover cost to build?

The README lists the total parts cost at roughly $1600, which it compares to the cost of a TurtleBot 3 Waffle. That figure covers the parts list for the base rover, and most of the mechanical assembly comes from GoBilda.

### Does the JPL Open Source Rover use ROS?

The README does not mention ROS. It states that a Raspberry Pi acts as the brain of the rover and that any method of communicating with a Raspberry Pi, such as bluetooth, WiFi or USB devices, can be interfaced into the control system.

### Is the JPL Open Source Rover still being developed?

The last push to the repository was on 2026-09-03, and the most recent release is v4.0.0 from 2023-09-14, described as the v2 design. The README tells builders to check issues, pull requests and the Slack forum for expected changes.

## Sources

- [License: Apache-2.0](https://github.com/nasa-jpl/open-source-rover/blob/master/LICENSE)
- [nasa-jpl/open-source-rover on GitHub](https://github.com/nasa-jpl/open-source-rover)
- [Project website](https://open-source-rover.readthedocs.io)
- [README](https://github.com/nasa-jpl/open-source-rover/blob/master/README.md)
- [Releases](https://github.com/nasa-jpl/open-source-rover/releases)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/nasa-jpl-open-source-rover