It’s a lot of fun telling the tale about ARISSat-1. So, when we were offered a table at the Microchip MASTERs Conference
, we accepted the invitation with enthusiasm. For the conference, we shipped in our fully functional demonstration satellite from the East Coast to Northern Phoenix and put it on display. This not only allowed attendees to see what ARISSat-1 looks like up close, but also get to hear it in action. With more than 600 engineers in attendance, there was ample opportunity to answer questions and queries (we tended to draw a crowd during class breaks and evening events).
Steve Bible (N7HPR) on left and Tim Moffat on right talk about ARISSat-1 to Microchip MASTERs attendees
Following MASTERs, an observation was made; it was very interesting to note the kinds of questions engineers would ask. So that spawned the idea for this post. What are the most frequently asked questions that engineers ask? Maybe they are the same questions you have…
An often asked question was, “Is this the same as the one in flight?”
The answer is yes. In the photo above, you can see the fully functional demonstration ARISSat-1 satellite in the lower right. I like to call this one “Number 4.” That’s because there were four space frames machined to create the two satellites that were shipped to Russia: Number 1 for flight and number 2 for backup flight. Units 3 and 4 are here in the States, and number 4 was specifically constructed for show demonstrations. But it is much more than a static display; it has working Internal Housekeeping Unit (IHU) and radio systems, and transmits the same greetings from space, spoken telemetry, BPSK telemetry and transponder as the flight unit (see Post #5
for more details on these systems). We had radios available so attendees could hear the greetings from space and also see the telemetry program, ARISSatTLM
, decoding telemetry.
ARISSat-1 Flight Unit #1 on left and Backup Flight #2 on right, ready for crating and shipping to Russia.
There is one major difference; there are Lexan
covers in place of the solar panels. This is because we only received eight panels from NASA. In the photo above you can see units 1 and 2, ready for crating. Notice number 1 on the left has solar panels, and unit 2 on the right has Lexan covers. The Lexan covers allow people to peer inside the craft. Which led to another often asked question, “Why is there so much room inside?”
There are two reasons. One, it is because ARISSat-1 was to be SuitSat-2, and inside the space frame are the boxes we originally meant to go inside the Orlan space suit. Two, the solar panels dictated the size of the space frame. The satellite measures roughly 21 by 21 by 11 inches, and weighs in at a little over 50 pounds (this was another question we heard a lot).“How did you get it into space?”
To answer this, I would explain that ARISSat-1 was a project of ARISS
—Amateur Radio on the International Space Station. ARISS is international in scope, and the team coordinates locally with their respective space agencies. For ARISSat-1, ARISS worked with the Russian Federal Space Agency (Roscomos)
and Energia Corporation
to “upmass” ARISSat-1 to the International Space Station, and deploy it during a Russian EVA
. “How was it deployed from the Space Station?”
People found it amazing that ARISSat-1 was hand carried outside of the ISS and ‘pushed’ away from the space station. I guess because everyone associates satellites with rockets.
“How many microcontrollers in the satellite?”
ARISSat-1 was deployed by hand from the International Space Station
and “What Microchip products did you use?”
The count is:
• Software Defined Transponder (SDX): PIC32MX
• Internal Housekeeping Unit (IHU): PIC32MX
• Power Supply Unit (PSU): PIC16F887
• Solar Max Power Point Converter (MPPT): PIC16F690 (x6), MCP1407
(x6)“Were the components radiation hardened?”
No, they were not. They are plain old off-the-shelf components. Most components are industrial-grade-temperature rated. As of this writing, ARISSat-1 has been operating in space for more than five weeks. With the exception of the battery failing open after eight days, the satellite has been operating nominally. It will be interesting to see how long ARISSat-1 will be operational with plain old off-the-shelf components.“How long will it last in space?”
Since ARISSat-1 was deployed down and away from the International Space Station, this placed it into a very low-Earth orbit. One that is decaying; i.e., ARISSat-1 is getting closer to Earth with every orbit. We estimate that, in about seven months (give or take) ARISSat-1, will reenter the atmosphere and burn up. Sometime before that, the satellite will heat up from friction with the atmosphere, and the electronics will fail at some point from excess heat. AMSAT is sponsoring a Chicken Little Contest
if you feel so inclined to participate!
As you can see, the questions were interesting in that one can see engineers love asking technical questions. So, you are in for a real treat in next week’s blog post, as we cover some of the team’s lessons learned.
Oh yeah, in October we’ll be crating and shipping the ARISSat-1 demonstration satellite to San Jose, California for the AMSAT Space Symposium
, which takes place November 4-6, 2011. If you stop by, you can see the satellite, listen to the talks, and meet many of the volunteers who made ARISSat-1 happen.
Until next week…
-Steve Bible (73 DE N7HPR
)ARISSat-1 Official Web Site
The Radio Amateur Satellite Corporation
Read the earlier Chips in Space blog posts, here