Al have a dream

February 7, 2015 11:04 AM

It came to Al Gore in a dream 17 years ago: An Earth-viewing satellite at L1, streaming a live image of the "blue marble" to an "all Earth, all-the-time" internet TV channel. NASA quickly constructed Triana (nicknamed GoreSat by its critics*) at a cost of $100 Million, but, after the 2000 elections, the satellite was literally shelved.

After being pulled out of storage in 2012 --- and repurposed to also serve as a Sun-facing replacement to the CME-detecting ACE satellite --- Triana (now DSCOVR) will launch on Sunday at 6:10PM EST (watch live on NasaTV).

Although "EarthTV" is not part of DSCOVR's primary mission, there are two Earth-facing instruments: (1) a radiometer designed to measure the total energy reflected/emitted by Earth toward the Sun and (2) EPIC, a 4 megapixel camera taking full-Earth images at 10 narrow-wavelength bands between UV and IR. EPIC will take photos approximately 4-6 times per day, which will be posted online 24 hours later.

The satellite will be launched by SpaceX, followed by a second attempt to land a rocket on a drone ship in the ocean (the first attempt, in January, did not go well). SpaceX chairman, Elon Musk, is optimistic about the return flight: "At least it should explode for a different reason."

* Dick Armey (R, TX) famously said, "This idea supposedly came from a dream. Well, I once dreamed I caught a 10-foot bass. But I didn't call up the Fish and Wildlife Service and ask them to spend $30 million to make sure it happened."

posted by pjenks (35 comments total)

On the surface, this seems rather similar to the ISS webcam. I mean, cool idea, but maybe some of it has already arrived.
posted by Going To Maine at 11:22 AM on February 7, 2015

Dick Armey is well named.
posted by Celsius1414 at 11:29 AM on February 7, 2015 [8 favorites]

I'm surprised that Space X is able to attempt another a landing on a mission to L1. Doesn't a destination that far away require a lot more delta V than all those trips to the space station?
posted by cirrostratus at 11:41 AM on February 7, 2015 [1 favorite]

I agree that the idea as originally conceived is stupid and a waste of money, but I'm glad the satellite was reclaimed for scientific purposes. The slightly better than HD images it beams back to earth are a nice bonus, too.
posted by Mr.Encyclopedia at 11:46 AM on February 7, 2015

Cool recycling project.
posted by clavdivs at 11:56 AM on February 7, 2015

Dish network has a channel that is a live picture of the Earth taken from one of their satellites. This channel has been live since 2008.
posted by Hatashran at 12:00 PM on February 7, 2015

"At least it should explode for a different reason."

I can't be the only person who immediately thought of GalaxyQuest, can I?
posted by feckless fecal fear mongering at 12:05 PM on February 7, 2015

I thought of Kerbal Space Program.
posted by dirigibleman at 12:12 PM on February 7, 2015 [1 favorite]

I'm surprised that Space X is able to attempt another a landing on a mission to L1. Doesn't a destination that far away require a lot more delta V than all those trips to the space station?

Depends on the mass of the satellite, and DSCOVR is only 570kg. That's the biggest win right there. Plus, getting to L1 doesn't require the ΔV that the LEO plane change from KSC's natural 28° orbit to the ISS's orbit of 51.65° does.

Since Earth-Solar L1 is so far away, and plane changes get cheaper the slower the vehicle is going, and objects further out in orbit orbit slower, what you do is launch to somewhere near L1. You'll pass through it, but slowly. Then you make your plane change burn, then the final insertion burn. To get to the ISS, you have to make that plane change burn as you are boosting to LEO or in LEO, which is markedly more expensive, so much so that the Shuttle would burn the OMS engines as well as the main engines to get extra payload up.

Another trick you can use is to use the Moon to alter the orbital plane during a flyby -- but I don't know if you could do that and land at the Earth-Sun L1 easily.

But between the easier PC burn and much less payload, there's probably going to be enough reserve to try to not sink the barge again.
posted by eriko at 12:24 PM on February 7, 2015 [7 favorites]

Thanks for explaining that, eriko! I didn't realize DSCOVR was so small and that the ISS orbit is so inclined. Seems like a lot of extra rocket fuel to do such a big plane change every time, I guess I'd better look up why we put the ISS where we did.
posted by cirrostratus at 12:30 PM on February 7, 2015

why we put the ISS where we did.

Russia. Their launch facility in Kazakhstan is at a higher latitude, and it would be significantly more difficult for them to reach the ISS if it weren't at least at that inclination.
posted by Hatashran at 12:51 PM on February 7, 2015 [3 favorites]

As a practical matter the higher inclination gives ISS coverage of more of the Earth for other experimental purposes. There are good arguments for it beyond making it cheaper for the Russians to reach it.

And the small size of DSCOVR is exactly why the same rocket that puts the 6,000 kg Dragon at the ISS can loft DSCOVR past the Moon.
posted by localroger at 1:02 PM on February 7, 2015 [1 favorite]

Just so they don't wreck the GCU.
posted by ROU_Xenophobe at 1:39 PM on February 7, 2015 [2 favorites]

At least the money didn't get wasted on studying volcanos
posted by thelonius at 1:52 PM on February 7, 2015

I wonder if SpaceX is going to have the blob-tentacle-porn LOX tank cam again.
posted by localroger at 3:27 PM on February 7, 2015 [2 favorites]

At least the money didn't get wasted on studying volcanos

NASA Robot Plunges Into Volcano to Explore Fissure

(As mentioned by Scott Manley, whose latest video I was just listening to. Listening rather than watching, since the in-game action so far in this livestream episode of his Interstellar Quest is not terribly exciting. He also says that Triana was originally scheduled to launch on STS-107, the final flight of Space Shuttle Columbia.)
posted by sfenders at 3:56 PM on February 7, 2015

I always thought it odd that when various TV communication satellites, such as the Galaxy and Echostar C-/Ku-band series, that they never thought it worthwhile (even as a PR/promotional/novelty project) to put a camera on one or more of them, point it at the Earth, and just offer it up as a free channel, giving a view of the earth from a geostationary orbit.

Sure, it would raise the price tag of those particular launches, but even after it's regular service life is over, one might even be able to figure out a way to have it only act as a camera from a graveyard orbit in some sort of low-power mode. With all the other silly short-term promotional campaigns these companies threw money at over the last 30 years, it just seems like a missed opportunity for an promotional investment that would keep on giving for years and years.

A bit of Googling says that DirectTV's Spaceway-1 satellite, launched in 2005, weighed in at 13,400-lb. Construction and launch costs (based on the numbers I found for the Spaceway-3 satellite): $300 Million. I couldn't find a separate launch cost, but using an average of $12k/lb for a geostationary orbit, that comes out roughly to $161 million to launch it.

So how much would a single camera system weigh, and what would be needed to have it added to this satellite's system, and build a camera that can handle being in that environment? Accounting for at least some of the modifications needed to put it in there, the housing, the wires, etc, I would be very surprised if it was added more than 40 pounds total, so there's an extra $480,000 added to launch it. To build the camera and add it to the design? I took my fist guess, thought about the engineers I know, and multiplied it by 5, and came up with $5 million. So, combining these numbers I just pulled out of thin air, we come to $5.5 million.

Sounds like a lot, right? But when you see that DirectTV spent almost $1.4 billion on advertising for new subscribers between 2010-2012 (DirectTV 2012 Annual report, p.71, ‘‘Subscriber acquisition costs"), $5.5 million, or even twice that amount, actually seems pretty affordable when it comes to acquiring new subscribers by offering a view of Earth for it's 12-year lifespan. Cancel just some of those almost weekly direct mail campaigns almost no one ever looks at and just throws away, and you've pretty much covered the cost. I don't know about you, but being able to see the Earth whenever I want is a far more tempting offer to get me to subscribe than a few months of free premium channels or the ability to record 5 shows at once.

But really, I would love to know if my development and launch cost estimates are anywhere near correct, or are just the ramblings of a guy who likes to Google these kind of things?
posted by chambers at 3:57 PM on February 7, 2015 [3 favorites]

chambers, if Jeff Bezos or Elon Musk were in the comsat biz, you'd probably be looking at the Earth from GEO right now.
posted by localroger at 4:11 PM on February 7, 2015 [1 favorite]

Dish network has a channel that is a live picture of the Earth taken from one of their satellites. This channel has been live since 2008.

The cameras from EchoStar 11 were taken off Dish Network in October 2012. Dish's explanation was that the cameras were "decomissioned". They probably started failing, and Dish probably wanted the bandwidth (small as it was) for something else.
posted by JoeZydeco at 4:58 PM on February 7, 2015 [1 favorite]

I'm surprised that Space X is able to attempt another a landing on a mission to L1. Doesn't a destination that far away require a lot more delta V than all those trips to the space station?

eriko answered the delta V part, but keep in mind that only the first stage returns to Earth to land. The second stage -- using SpaceX's most advanced engine, the Merlin 1D (Vacuum) -- is the one that needs to generate that delta V. Details here.
posted by dhartung at 5:04 PM on February 7, 2015

That same site also has a page on DSCOVR, which tells me that the SpaceX craft is not planning to go anywhere near L1, its mission is only to fling GoreSat away from the earth in that general direction. DSCOVR reportedly has 600m/s of delta-v of its own, much of which will be used in getting there and slowing down when it arrives.
posted by sfenders at 5:58 PM on February 7, 2015

eriko answered the delta V part, but keep in mind that only the first stage returns to Earth to land. The second stage -- using SpaceX's most advanced engine, the Merlin 1D (Vacuum) -- is the one that needs to generate that delta V

Nope. ΔV is ΔV. If you choose to not generate it with the first stage, you have to generate it with later stages.

Space X's explanation of "The first stage always has extra" is bullshit. Every single flying booster other than the Falcon 9 flies the first stage until either the oxidizer or the fuel hits a limit sensor. Then, and only then, do you stage.

Space X is deliberately throwing away ΔV to try to recover the first stage. This, in fact, may be a good answer. But the idea that you always have spare ΔV in the first stage is unmitigated bullshit. If SpaceX is staging with fuel and oxidizer in the tanks, they've left ΔV on the table.

If you somehow do have spare, you don't throw it away on staging. You burn everything but the last stage until it dies. Then, and only then, do you light the last stage. Because getting payload to orbit is in fact *that hard.*

Tsiolkovsky rocket equation. ΔV = v_e(ln( M₀/M₁)) It does not lie. Every gram you use to land a first stage counts against M₀. The fact that SpaceX used RP/LOX rather than LH₂/LOX in the second stage counts against v_e.

You can fool investors, you can fool the internet, but you cannot fool physics. If you're burning the first stage after staging, you left ΔV on the table, and if you're burning to a point to cancel out 1g, you left a bunch of ΔV on the table.

And to cancel out more than 1g? Well...physics.
posted by eriko at 9:20 PM on February 7, 2015 [4 favorites]

I love that Musk puts on a public face that makes failure an okay thing. He demonstrates that everything is about learning to do better.
posted by five fresh fish at 11:25 PM on February 7, 2015

eriko, you are quite simply wrong. The goal of satellite launches is not to get the satellite as high as possible, it's to get it to a target orbit. As such, every phase of the flight is targeted to achieve a very specific final vector. Inasmuch as there are uncertanties as to burn rates, efficiencies, and so forth, all design elements are targeted so that in the worst case scenario of all the uncertainties, the target vector can be achieved. In practical terms this means there is significant excess capacity built into every stage. There has to be so that you can still complete the mission if some little thing goes wrong. And since things usually go better than worst-case, you tend to end up cutting off the rocket with fuel remaining when the stage's target is achieved.

There is no point at all to getting a little extra thrust from the first stage if you do better than this worst-case design point, because the second stage is also designed to fulfill its mission starting from the first stage's target.

The only rockets that are designed to burn until all the fuel is gone are solids which can't be turned off once lit. And except for very simple missions like sounding rockets or the tiny all-solid Scout solids are almost always trimmed by a following or parallel liquid stage which allows the uncertainty in the solid stage to be corrected.
posted by localroger at 5:33 AM on February 8, 2015

eriko is right. SpaceX is deliberately and necessarily sacrificing ΔV (i.e., mass-to-orbit) for reusability. They've said so:

SpaceX President Gwynne Shotwell says Falcon 9's reusability is already designed into the rocket's first stage, including the weight of the landing legs that would otherwise detract from the rocket's performance. She also said Falcon 9 retains 30% performance margin over the company's advertised mass-to-orbit capability of 4,850 kg to GTO – margin SpaceX is using to conduct operational trials of a reusable Falcon 9 first stage.

“The mass of the recovery hardware is not a dramatic impact on payload performance,” Shotwell said in a February interview. “Conservatively, if I put 1,000 lbs on the first stage, I'm only losing 100 pounds of payload or so to orbit. What impacts is the fuel we need to reserve to execute the reentry and the landing burns.”

They've said they're retaining 30% performance margins. That's not a lucky happenstance of having propellant left in the first stage, that's a deliberate design choice. Other comparable first stages (such as the Delta IV CBC) don't leave anything in the tank, burning until sensors report that the propellant is exhausted.
posted by ddbeck at 9:03 AM on February 8, 2015

Ddbeck nothing you quote supports erico. Spacex is making the required design performance that the spec requires. If they are sacrificing DV it's DV they're not being asked to provide. As long as they deliver the payload to the target altitude and velocity everything else is lagniappe.
posted by localroger at 11:51 AM on February 8, 2015

I don't get it, localroger. I don't think anyone's suggested that SpaceX is delivering less payload to orbit than advertised. I think eriko was challenging the idea (one sometimes promulgated by Elon Musk) that SpaceX's reusability experiments have been cost-free in terms of the rocket's capabilities. What I meant by quoting that article was that a Falcon 9 used without reusability in mind, all other things being equal, would have a significantly larger ΔV budget.

As the rocket is presently operated, there's considerable ΔV spent—wasted, if your point of evaluation is mass to orbit—on returning the rocket to the ground. The first stage expends tons of propellant to achieve a certain velocity, stages, and then expends more propellant to null that velocity in the first stage. A return-to-launch-site landing would require the first stage's entire velocity to be returned to that of the stage at lift off. You get some of that vector nulled for free in terms of atmospheric drag, but you have to pay for the rest with propellant—propellant that you have to haul up to your staging point (and now we're back to the ideal rocket equation).
posted by ddbeck at 2:09 PM on February 8, 2015

A return-to-launch-site landing would require the first stage's entire velocity to be returned to that of the stage at lift off.

Well yeah, but the first stage mass at launch is about 95% propellant. It may need the same delta-v on return, but with enormously reduced mass. I don't understand why you'd need "30% of first-stage fuel" to do the same acceleration with atmospheric drag helping, much less fuel, and the rest of the rocket out of the way.
posted by sfenders at 2:43 PM on February 8, 2015 [1 favorite]

But SpaceX's reusability experiments have been cost-free in term of the rocket's requirements. NASA wrote specs for a delivery system, and SpaceX managed to exceed those specs well enough to sneak some extra stuff into the mission. What that extra stuff gets you is a free, relatively unscathed and reusable first stage, which isn't peanuts. It is in fact a large fraction of the cost of the entire mission, much more expensive than for example the fuel. So saving that first stage, and very particularly the engines, is a major win if you can do it without missing the target objective.

Eriko's objection that they are Wasting! Delta! Vee!!!! is just hysterical hyperbole. They are doing what many missions have done in the past, which is turning the rockets off and staging when the first stage has achieved design delta vee instead of burning it dry. That they can do so with enough fuel remaining and the necessary avionics onboard to soft return the first stage costs nobody anything, because they made the design objective.

Sure you can argue that they could put even more in orbit if they didn't waste those pounds, but I have followed their math and it is sound. These are not stupid people and they're not grandstanding. The actual fuel is less than ten percent of the cost of a launch. Saving that stage is a big win and they are in fact doing so within the very design parameters that their competitors were targeting with the stage totally thrown away.

The ultimate fact is that Falcon 9 gets 6,000 KG into LEO, which is what it was designed to do. If it can do that within budget and while also recovering the first stage, then the recovered first stage is in fact free.
posted by localroger at 2:46 PM on February 8, 2015 [1 favorite]

Also, as a particular point -- missions to the ISS, which often have launch windows of 1 second or so, are particularly prone to require exact timing and to not benefit from burning the first stage dry. And that mission, of course, is the primary one for which the F9 was designed.
posted by localroger at 2:48 PM on February 8, 2015

Launch scrubbed for today due to "tracking issue".
posted by pjenks at 3:11 PM on February 8, 2015

OK who was flying a quadcopter downrange?
posted by localroger at 3:13 PM on February 8, 2015

The Kerbal News version includes the best simulated rocket landing on a barge I have ever seen.
posted by sfenders at 5:31 PM on February 8, 2015

They did not get to crash another rocket into a "drone ship" due to bad weather at sea, but still it was a beautiful launch. Good luck little satellite.
posted by sfenders at 3:56 PM on February 11, 2015

Successful soft landing in the ocean confirmed. The other end went off without a hitch, as well. DISCOVR is on it's way to L1.
posted by dirigibleman at 4:03 PM on February 11, 2015