Student Rocket Makes It To Space

Where does the Earth’s atmosphere stop and space begin? It is tempting to take the approach Justice Potter Stewart did for pornography when judging a 1964 obscenity case and say “I know it when I see it.” That’s not good enough for scientists, though. The Kármán line is what the World Air Sports Federation (FAI) defines as space. That line is 100 km (62 miles or about 330,000 feet) above sea level. A recent student-built rocket — Traveler IV — claims to be the first entirely student-designed vehicle to pass that line.

The students from the University of Southern California launched the rocket from Spaceport America in New Mexico. The new record is over twice as high as the old record, set by the same team. The rocket reached approximately 340,000, although the margin of error on the measurement is +/- 16,800 feet, so there’s a slight chance they didn’t quite cross the line.

As you might guess from the name, there were three other Traveler rockets. The 3rd one blew up spectacularly as rockets sometimes do. The other two also blew up, although somewhat less spectacularly. The successful rocket was 13 feet tall and 8 inches in diameter. The 11 minute flight accelerated at over 17gs to a top speed of 4,970 feet/second which is over Mach 5.

The line, by the way, is not universally accepted. NASA and the US Air Force award outer space wings at 50 miles above sea level — the rocket definitely crossed that line. We don’t think our water rockets will get there. The first man-made object to reach space, by the way, was the V2 rocket.

Photo credit: [Neil Tweksbury] via USCViterbi web site.

23 thoughts on “Student Rocket Makes It To Space

  1. I am impressed. Maybe for the Traveler V they could put in a small container with some live fleas in it, that way they could be the first civilian to put animals into space, and I don’t think many people would be too upset that the payload won’t be recovered alive.

      1. I was thinking cockroaches but fleas are smaller, so their container can be smaller and cockroaches are just gross, if someone is sending them into space I don’t want them coming back to Earth!

    1. Air pressure is very difficult to measure at that altitude. I think you’d need an ionization gauge, and good luck protecting that from contamination with all that gunk that got on the camera window.

      A measurement like that would be based on inertial measurements, radio rangefinding, or an unlocked GPS. A margin that large means they didn’t have an unlocked GPS, so you’re left with accelerometer/gyro integration or radio rangefinding. Inertial sensors are much easier to find.

      (and when I went to check my assumptions after writing that, it turns out they described this in great detail: http://uscrpl.com/s/Traveler-IV-Whitepaper)

      1. Is there a chance, using the time delay of radio signals to determine the distance?
        1 km approximately equates to 30 µs; therefore could one possibly receive repeatedly sent signals timed by a TCXO which has been synchronized directly prior launch? I’ve seen TCXO precision specs stating e.g. +- 4.3 ms / day; which would translate in roughly 3 µs/ min.
        Disclaimer: I have no practical experience in this field, just my two cents…

      1. You go and do better, then! It seems that keeping a camera lens clean and clear through hypersonic flight is not a trivial matter — SpaceX and Rocket Lab have both had poor views from their on-board cameras at times.

        In this case, I think the issue was mostly ablation of resin or paint from the airframe. Just look at what’s left of the leading edges of the fins at 4:22 in the video. The nose cone looked better, presumably having been made of more heat-tolerant material, but even a little bit of surface coating coming off could easily contaminate the camera window like that.

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