artemis1 – Daniel Estévez

More details about Orion uncoded telemetry

In a previous post I analysed the residual carrier telemetry of the Artemis I Orion capsule using some recordings done by CAMRAS with the 25 m radio telescope at Dwingeloo observatory. I noticed that, in contrast to some recordings that I had done early after launch with the Allen Telescope Array, in those recordings the telemetry was uncoded instead of using LDPC. I related that finding to some tweets from Richard Stephenson about the project switching frequenctly between residual carrier and OQPSK, and between uncoded and LDPC.

I wanted to study the situation in more detail, for example to see what combinations of residual carrier / OQPSK and uncoded / LDPC were possible. Since CAMRAS hasn’t made available on their web server all the recordings they did, due to disk space constraints, I asked them to publish a few additional recordings that seemed interesting to this end. This is a short post with my findings about those new recordings.

Decoding the Orion residual carrier telemetry

The Orion Muli-Purpose Crewed Vehicle was the main spacecraft of the Artemis I mission. In a previous post I showed how to decode its OQPSK S-band telemetry signal, using a recording I made with the Allen Telescope Array. I mentioned that besides the OQPSK modulation, Orion sometimes used a different modulation with a residual carrier. This residual carrier modulation will be the topic of this post.

Decoding ArgoMoon

ArgoMoon is one of the ten cubesats that were launched in the Artemis I mission. It was built by the Italian private company Argotec, and its main mission was to image the ICPS after the separation of Orion, and while the other cubesats were deployed.

In 2022-11-16, about seven hours after launch, I used two antennas from the Allen Telescope Array to record telemetry from the Orion vehicle and some of the cubesats. Since then, I have been posting regularly as I analyze these recordings and publish the data to Zenodo. In this post I will look at two recordings of the X-band telemetry signal of ArgoMoon at 8475 MHz. In the two recordings, different modulation and data rate is used.

The recordings are available in the dataset Recording of Artemis I ArgoMoon with the Allen Telescope Array on 2022-11-16 in Zenodo.

Decoding EQUULEUS

Here is a new post in my Artemis I series. EQUULEUS (called EQUL by the DSN) is one of the ten cubesats launched in the Artemis I mission. It is a 6U spacecraft developed by JAXA and University of Tokio. Its mission is to study the Earth’s plasmasphere and to demonstrate low-thrust trajectories in the Earth-Moon region using its water thrusters. The spacecraft communications are supported mainly by the Japanese Usuada Deep Space Center, but JPL’s Deep Space Network also collaborates.

I did an observation of the Orion vehicle and some of the cubesats with two antennas from the Allen Telescope Array some seven hours after launch. As part of this observation, I made a 10 minute recording of the X-band telemetry signal of EQUULEUS as it was in communications with the DSN station at Goldstone. I have published the recording in the Zenodo dataset Recording of Artemis I EQUULEUS with the Allen Telescope Array on 2022-11-16. In this post, I analyze the recording.

Decoding LunaH-Map

This post is a continuation of my Artemis I series. LunaH-Map, also called Lunar Polar Hydrogen Mapper (and called HMAP by the DSN) is one of the ten cubesats that were launched with Artemis I. It is operated by Arizona State University, and its main mission was to use a scintillation neutron detector to investigate the presence of hydrogen-rich compounds such as water around the lunar south pole. Unfortunately, it was unable to perform its required lunar orbit insertion burn. Nevertheless, the spacecraft seems to be functioning well and some technology demonstrations and tests are being done with its subsystems. With some luck, there might be opportunities for this satellite to move to lunar orbit in the future.

In my observation with the Allen Telescope Array done about seven hours after the Artemis I launch I did some recordings of the LunaH-Map X-band telemetry signal when it was in communications with the DSN grounstation at Goldstone. First I did a 10 minute recording at 15:00 UTC. Then I noticed that the spacecraft had changed its modulation, so I did a second recording at 15:16 UTC, which lasted ~7 minutes. Unfortunately, I didn’t record the moment in which the telemetry change happened.

I have published these two recordings in the dataset Recordings of Artemis I LunaH-Map with the Allen Telescope Array on 2022-11-16 in Zenodo. This post is an analysis of the signals in these recordings.

Artemis I Orion recordings published

In my previous post, I described the observations I had made with the Allen Telescope Array of the Orion vehicle and some of the cubesats of the Artemis I mission following the launch. I showed how to decode the 2 Mbaud OQPSK S-band telemetry signal from Orion using GNU Radio and aff3ct for LDPC decoding. In the post I indicated that I wanted to publish all these recordings in Zenodo, but since I had recorded a large amount of IQ data, I first needed to review the recordings and see what to publish and how to reduce the data.

I have now reviewed the recordings of the Orion 2216.5 MHz signal, and published them in the following datasets:

Additionally, I have published the decoded AOS Space Data Link telemetry frames in the dataset Decoded Artemis I Orion S-band telemetry frames recieved with the Allen Telescope Array on 2022-11-16.

Decoding the Artemis I Orion vehicle

On Wednesday 16th, the Artemis I mission was launched from Kennedy Space Center. This mission is the first (uncrewed) flight of the Orion Multi-Purpuse Crew Vehicle that will be used to return humans to the Moon in the next few years. Together with Orion, ten cubesats with missions to the Moon and beyond were also launched.

Seven hours after launch, I used two spare antennas from the Allen Telescope Array to record RF signals from Orion and some of the cubesats. By that time, the spacecraft were at a distance of 72000 km, increasing to 100000 km during the 3 hours that the observations lasted.

I have collected a lot of data on those observations, around 1.7 TB of IQ recordings. I am going to classify and reduce this data, with the goal of publishing it on Zenodo. Given the large amount of data, this will take some time. I will keep posting in this blog updates on this progress, as well as my results of the analysis of these signals.

Today’s post is about Orion’s S-band main telemetry signal, which is transmitted at 2216.5 MHz. This signal has attracted great interest in the spacecraft tracking community because back in August NASA published an RFI giving the opportunity to ground stations belonging to private companies, research institutions, amateur associations and private individuals to track the S-band signal and provide Doppler data to NASA. Some of the usual contributors of the amateur space tracking community, including Dwingeloo’s CAMRAS (see their results webpage), Scott Chapman K4KDR and Scott Tilley VE7TIL (see his Github repository) are participating in this project.

Shortly after Artemis I launched, Amateur observers in Europe, such as Paul Marsh M0EYT, the Dwingeloo 25m radiotelescope, Ferruccio Andrea IW1DTU, Roland Proesch DF3LZ, were the first to receive the signals. They were then followed by those in America.