SpaceX Launches Falcon Heavy Rocket on Historic Maiden Voyage

February 6th, 2018

Update: Astronomers Spot Musk’s Roadster

Via: Virtual Telescope:

The car was about as bright as magnitude 15.5, requiring a large (more than 16? – 400 mm in diameter) to be seen visually.

Below is a video, obtained with 54 images taken back to back, from 11:12 to 12:15 UT, 8 Feb. 2018.

Update: Was Roadster Spectacle and Subsequent Final Burn a Demonstration for the Pentagon?

Ok, now we’re getting somewhere. Couple more category ticks: [???] and War.

Via: Robert Walker:

No, it wasn’t left in that orbit which was a temporary holding orbit. Immediately after the launch it was in a temporary orbit with maximum altitude 7,000 km, then five hours later they did a final burn to put it on an interplanetary orbit out to beyond the orbit of Mars. They could have done that right away without going into the orbit at all – but as a requirement for future military launches, apparently they had to prove that their final stage could withstand spending a long time in the Van Allen belts. That’s why they deliberately kept it going through the Van Allen belts over and over for five hours before sending the payload into its interplanetary orbit.

Update: What Is Powering the Communications Package on the Roadster Payload?

On Live Views of Starman, there’s a video feed from the Roadster hurtling through space. Within a few seconds of watching that with my jaw hanging slack, I wondered, “What’s powering the coms package on that thing?”

At first, I wondered if it was the battery pack from the Roadster itself. But if it’s using the car’s battery, how long would that last at -270C?

I wasn’t able to find anything out about this. Can anyone help me out here?

Update: Email From “A Source That Works At A Rocket Company”

He asked not to be identified, so I’ve removed his name and his employer:

Hi Kevin,

I’d be happy to explain how the Falcon Heavy launch worked and answer any questions you have.

The basic idea of how the batteries don’t freeze is that they are in the sunlight (so long as they’re not in the shadow of the earth), and the whole stage is on what’s called a “barbeque roll” rotation with a period of 1-2 minutes. That roll keeps the sun-facing side of the vehicle from getting too hot, and the space-facing side from getting too cold. Deep space is the temperature of the microwave background radiation, which is 2.7 Kelvin, and the Sun is of course around 5800 K (but it doesn’t take up half the sky, only as much area as the moon approximately). When you time-average those two exposures together, the result is approximately room temperature. This is the same reason that the Earth is also approximately at room temperature

As far as I know, there has never been a rocket 2nd stage which included solar panels; they all run on batteries. So you get a fixed amount of time before the batteries run out. Sputnik 1 had batteries to last something like 4 days. Rocket 2nd stages tend to have batteries good for roughly 3 hours, unless you need to do a longer mission profile such as a direct insertion to geostationary orbit. In that case, it takes the stage about six hours to climb up from low Earth orbit to the geostationary belt which is roughly six Earth radii up (quite far out there!). So for a direct GEO mission, you need to add on extra batteries for the 2nd stage so it can stay alive and do its final burn six hours later. That six hour number is dictated solely by the mass & radius of the Earth, Newton’s gravitational constant, and the rotation rate of the Earth. The characteristics of the rocket have nothing to do with it (unless I suppose you took a faster but less fuel-efficient route by blasting yourself up faster, but nobody does that).

During that six hour coast phase, the vehicle gets to experience a ton of trapped solar particles bouncing around in the Earth’s magnetic field, also known as the Van Allen belts. The radiation levels are much much higher than down in low orbit where for instance the ISS resides, and they are actually also generally higher than the radiation levels once you get up into the operational GEO orbit. The electronics controlling the 2nd stage have to be designed to withstand that onslaught in a way that they don’t have to be designed for for a regular LEO or GTO insertion mission profile.

Just for reference, it doesn’t take all that much power to send down the live video stream you saw yesterday. I haven’t looked up the FCC filings (which are public!), but on some previous missions they have used a 20 watt transmitter operating near 2200 MHz for video. That power level and frequency are quite sufficient even for going further away from the Earth’s surface like they did yesterday; all you need is a bigger dish on the ground to pick it up. Remember, NASA picked up live video from the Moon in 1969 using a 70 meter dish. Probably yesterday SpaceX was using something like a 15 meter dish. They didn’t have to go install it themselves, either, there are plenty of dishes already in existence that are available to rent for missions like this.

Let me know if there’s anything else you’d like explained.

Follow up email:

Also,

“Also, the livestream from the car cut out after about 4 hours 40 minutes. So it probably used up the car’s battery, and or some other battery, to keep itself warm and to send the video stream back to Earth, and that’s all she wrote.”

There are two possible reasons they cut off the video stream. #1, the payload was actually on its way back down so they went out of range of their round stations. I haven’t checked the orbital mechanics to verify whether or not this was a contributing factor. #2, I think they wanted to cut the feed before the (still risky) 3rd ignition of the 2nd stage, in case it went poorly. Interestingly, there were visual sightings from Los Angeles of what turned out to be that 3rd burn, propelling the vehicle on its Earth-escape trajectory.

I suspect they still had enough battery to keep the video downlink going, and assuming they did record that data, perhaps they’ll leak some of it out in the future now that they know the vehicle didn’t fail during that 3rd burn

Via: space.com:

The first Falcon Heavy rocket built by the private spaceflight company SpaceX soared on its maiden voyage today (Feb. 6) — a historic test flight that also sent a car toward Mars and included two confirmed booster landings.

Billed as the world’s most powerful booster since NASA’s Saturn V, the Falcon Heavy rocket lifted off from Launch Pad 39A here at Kennedy Space Center (KSC) — the same site used by NASA’s Apollo moon missions and space shuttles — at 3:45 p.m. EST (2045GMT).

“I’m really excited about today,” SpaceX CEO Elon Musk told reporters after the launch. “I’m really proud of the SpaceX team. They’ve done an incredible job of creating the most advanced rocket in the world, and the biggest rocket in the world.”

Standing 23 stories tall, the Falcon Heavy rocket is SpaceX’s largest rocket yet. Its first stage is powered by three core boosters based on SpaceX’s Falcon 9 rockets, with 27 engines (nine per booster) firing in unison to produce about 5 million lbs. of thrust (22,819 kilonewtons) at liftoff. While SpaceX hoped all three boosters would return to Earth and land, the center core missed its mark – a minor hiccup in an otherwise successful launch, Musk said.

7 Responses to “SpaceX Launches Falcon Heavy Rocket on Historic Maiden Voyage”

  1. Dennis Says:

    I don’t know anything about this stuff really, but I imagine a second Tesla battery, mounted flush with the first, both insulated and with one powering an enclosing heating element (small potatoes for its capacity) to keep both at around 10 C. Of course, the heating element would need to be switched on before the batteries cooled, and I guess it could all be kept charged by solar…?

  2. Dennis Says:

    …and I guess it would make sense to reconfigure the cells to make the battery cuboid or spheroid to minimise heat loss.

  3. Kevin Says:

    I didn’t see any solar panels on the payload/Roadster. Also, the livestream from the car cut out after about 4 hours 40 minutes. So it probably used up the car’s battery, and or some other battery, to keep itself warm and to send the video stream back to Earth, and that’s all she wrote.

  4. Kevin Says:

    It used the car’s battery:

    https://www.space.com/39612-spacex-starman-tesla-roadster-live-views.html

    SpaceX has not yet said how long the live stream will last, but the Tesla’s battery will only last for about 12 hours after liftoff, Musk said in a post-launch briefing at Kennedy Space Center.

  5. Kevin Says:

    Hold on…

    It didn’t use the car’s battery. It used systems from the second stage:

    https://www.quora.com/Will-the-roadster-Elon-Musk-just-sent-to-Earth-orbit-with-the-Falcon-Heavy-be-left-in-orbit-If-yes-do-we-expect-it-to-re-enter-the-atmosphere-on-its-own/answer/Robert-Walker-5?__nsrc__=4&__snid3__=1981825751

    The Tesla car had no batteries. It remains attached to the second stage and was transmitting back via the second stage which had power for only twelve hours. It’s just a dead object now with no way of communicating home and a small object so will be impossible to detect except for the occasional close flyby of Earth or better telescopes than we have now.

  6. Dennis Says:

    Thanks to you and the source for the fascinating explanation!

  7. Dennis Says:

    Tesla’s heading to Mars and beyond:

    http://www.smh.com.au/technolo.....4yzro.html

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