Iris

Carnegie Mellon University.

Overview

Iris is a 2.2 kg lunar nanorover built by students at Carnegie Mellon University, housed in a shoebox-sized carbon fiber chassis [5]. It was carried on Astrobotic’s Peregrine lander, launched 8 January 2024 on the first flight of the Vulcan rocket [3]. A propulsion anomaly prevented the landing, and Iris was operated in cislunar space instead, then destroyed with the lander on controlled re-entry on 18 January 2024.

Iris was intended as a proof of technology and as a mobility test for low size, weight, power and cost lunar rovers [1], and to collect images for geological science [4].

Iris originated in the same Carnegie Mellon work that produced the Astrobotic CubeRover line, and was the first flight rover from that effort.

Specifications

Parameter	Value	Source
Mass	2.2 kg	[5]
Chassis	carbon fiber monocoque
Wheels	multi-ply carbon fiber, bottlecap form	[1]
Flight computer	single board computer, custom	[1], [5]
Flight software	JPL F Prime	[1]
Sensors	IMU, two cameras, odometry, UWB module	[2]

Carnegie Mellon news material gives 2.2 kg [5], and the 2020 preprint written during development describes a four pound rover [2]. No source reconciles the two. Wheel mass, ground clearance and obstacle height were stated only in a conference abstract, which is not a citable source, and are omitted here.

Mission profile

These describe Peregrine Mission One, not the rover.

Parameter	Value
Lander	Astrobotic Peregrine
Launch vehicle	United Launch Alliance Vulcan, maiden flight
Launch	8 January 2024, 02:18 ET, Cape Canaveral
Anomaly	oxidizer tank rupture after PCV2 actuation
Mission duration	10 days 14 hours
Peregrine distance traveled	more than 860,000 km (535,000 miles)
End of mission	controlled re-entry 18 January 2024, 16:04 ET, South Pacific

Figures from [3].

Peregrine activated its avionics and power management system at 03:16 ET on 8 January 2024 and established communications through the Deep Space Network [3]. During propulsion commissioning, actuating the oxidizer-side pressure control valve PCV2 let helium flow uncontrollably into the oxidizer tank, which over-pressurized and ruptured, and the tank leaked oxidizer for the rest of the mission. With landing impossible, mission priorities were changed to collecting propulsion data for the investigation, powering and communicating with payloads, and raising subsystem technology readiness levels. Nine of the twenty payloads were designed to communicate with the lander and all nine returned data; the other eleven were passive. On 13 January, in consultation with NASA, Astrobotic decided to end the mission to avoid a debris event in cislunar space [3].

Iris completed a subset of system validation tests aboard the lander [1]. Two-way communication with the rover was established and telemetry returned [5]. The rover survived launch loads and the space environment.

A rover deployment concept was developed in flight but not executed: ejecting Iris from the lander during lunar transit so that it could image the lander it was leaving [4]. Peregrine re-entered with Iris still attached [3], [5].

Mobility

Iris is a wheeled rover. Mobility testing on the ground used low-cost lunar environment simulation tools for gravity offloading and surface operations [1].

The wheels are the design result of the mass target. They are multi-ply carbon fiber in a bottlecap form, a flat disc face with a cylindrical rim carrying molded grousers, rather than a spoked or compliant metal wheel [1]. Wheel mass, ground clearance and obstacle performance appear only in a conference abstract and are not repeated here.

Power and energy

Custom power management electronics were flown [1]. Power source, generation and battery capacity are not published. Iris was a short-duration surface mission and no night survival capability is claimed.

Thermal

The chassis carries multi-layer insulation over the carbon fiber monocoque. Published thermal work covers modeling processes and their terrestrial validation [1]; no temperature limits or heater powers is published. Carnegie Mellon reports that the rover endured extreme temperatures and high radiation levels during the ten day flight with primary systems performing normally [5].

Compute and avionics

A single board computer, custom built, is the flight computer [1], [5]. Power management is also custom. Flight software is an implementation of JPL’s F Prime framework. Processor part, memory and radiation tolerance approach are not published.

Autonomy

Iris was designed to be driven from the ground. The published architecture puts localization off the vehicle: onboard localization relative to the lander uses an ultra-wideband module, and the SLAM and visual-inertial odometry computation runs on the ground rather than onboard, because using RF for both communication and state estimation saves mass and power the rover does not have [2]. The onboard sensor suite is an IMU, two cameras and odometry sensors, plus the UWB module. The rover was operated from the ground throughout the flight it flew [5].

The ground-side perception pipeline proposed for the mission is object-level SLAM that optimizes the pose and shape of the lander jointly with the rover camera trajectory, using the known lander location as a prior, with a semantic segmentation front end fine-tuned from DilatedResnet-101 and UperNet-101 trained on ADE20K to produce the lander mask [2]. A video frame interpolation stage synthesizes intermediate images between camera samples, using a depth-aware flow projection layer, to compensate for the low frame rate the link allows.

Communications

Iris has no direct-to-Earth link. It communicates through the lander, and the same ultra-wideband link that localizes the rover relative to the lander is the data path, with the lander acting as the way station [2].

Payload and instruments

Iris carries no science instruments. The two cameras are the payload: the declared objective was collecting images for geological science [4], on a vehicle that was itself a mobility technology demonstration [1].

Modes of operation

Deployment from the lander deck used a drop mechanism, modeled and published as part of the system description [1]. No mode set beyond stowed, deployed and driving is published. In flight, with the lander unable to land, the mission control team modeled an alternative: eject the rover during lunar transit and use it to image the lander [4].

Ground operations

Operated by a student mission control team at Carnegie Mellon [1], [5]. Published ground elements are adaptable control software and an accelerated operator training program. Three hundred students across seven Carnegie Mellon colleges worked on Iris, with about thirty in Florida for launch. When the landing became impossible, the team continued operating the rover from a rented house near the launch site for the remainder of the ten day flight.

Technologies developed

The result that outlived the vehicle is the carbon fiber structure: a chassis and wheels built from carbon fiber that survived launch and the space environment [1], [5]. The program also produced a documented model for university flight rover development, covering integration phases, operator training and mission control practice [4].