jfc they couldn’t get a shot without their finger in front of the lens? And those were the “top three images”?
But seriously, cool pictures.
Disappointing that this little guy got cancelled:
Mercury Surface Element (cancelled)
The Mercury Surface Element (MSE) was cancelled in 2003 due to budgetary constraints.[8] At the time of cancellation, MSE was meant to be a small, 44 kg (97 lb), lander designed to operate for about one week on the surface of Mercury.[28] Shaped as a 0.9 m (2 ft 11 in) diameter disc, it was designed to land at a latitude of 85° near the terminator region. Braking manoeuvres would bring the lander to zero velocity at an altitude of 120 m (390 ft) at which point the propulsion unit would be ejected, airbags inflated, and the module would fall to the surface with a maximum impact velocity of 30 m/s (98 ft/s). Scientific data would be stored onboard and relayed via a cross-dipole UHF antenna to either the MPO or Mio. The MSE would have carried a 7 kg (15 lb) payload consisting of an imaging system (a descent camera and a surface camera), a heat flow and physical properties package, an alpha particle X-ray spectrometer, a magnetometer, a seismometer, a soil penetrating device (mole), and a micro-rover.[62]
Reminds me of the zillions of micro-landers I’ve built in Kerbal Space Program (except I had to land those by hand, no airbags).
Was 44 kg the total budgeted weight of the MSE including propulsive fuel, or the dry weight of the lander once down? Braking from a high elliptical orbit to surface is no small amount of delta-v on Mercury; no aerobraking available.
Good question. I presume this would be separated from the MPO (Mercury Planetary Orbiter), which is in a lower 480x1500 km orbit. That would require about 3 km/s delta V if we ignore gravity losses. You could maybe hit a 3:1 mass fraction with storable bipropellant (hydrazine/NTO). Tricky, though.
A bit more info:
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2018-080A
The MSE is a 0.9 m diameter disc which is designed to land at a latitude of 85 degrees near the terminator region. Following the release of the MMO, a burn of the 4 kN thruster will put the MSE into a 10 km orbit. Another braking maneuver controlled by gyros/accelerometers and an optical range/range-rate sensor will bring the MSE to zero velocity at an altitude of 120 meters at which point the propulsion unit will be ejected, the airbags inflated, and the module will fall to the surface with a maximum impact velocity of 30 m/s.
A 4 kN engine is quite powerful! That’s 9 gees acceleration for a 44 kg lander… even more once the propellant is partially depleted. So it should have little gravity loss. And the 10 km orbit is also quite low.
I was admiring the fall from 120 meters in vacuum which results in an impact velocity of 30m/s! 30m/s is fast; like 50-60mph. I personally would not want to impact a hard surface at that speed. I’m rather surprised Mercury gravity could deliver that much acceleration. But they’re the experts, not me.
I just looked it up and Mercury’s surface gravity is 3.7 m/s/s, or ~37% of Earth’s. On a mass of ~5% of Earth but with ~38% of Earth’s radius & volume. The density is similar to Earth. It’s interesting how theses various factors scale differently against one another. Very ballpark it’s a 1/3rd scale model of Earth located in a really shitty neighborhood for harboring surface life.
Mercury is surprisingly dense–the second-densest planet in the solar system after Earth, but without the excuse of being massive enough to compress its core. It’s just got a whole lotta iron in it.
30 m/s is pretty fast, but Spirit and Opportunity landed at about 24 m/s (again with airbags). And they were fairly large rovers, while the MSE is smaller and probably less delicate, so it can handle a higher impact speed. And of course you can design the airbags to be as compliant as necessary (at the expense of mass).
Interestingly, Mars and Mercury have similar surface gravities.
More interestingly, the surface gravities of the major astronomical bodies of the solar system seem to fall into rough groupings; even more interestingly those groupings seem to be separated by a factor of approximately 1:2.5; I’d love to see a logarithmic graph of this. (data Wikipedia; the gas giants’ surface gravities vary significantly equator to poles due to fast rotation):
Jupiter: 24.79 m/s2 =2.528 g0
Neptune: 11.15 m/s2 =1.137 g0
Saturn: 10.44 m/s2 =1.065 g0
Earth: 9.80665 m/s2 =1 g0
Venus: 8.87 m/s2 =0.904 g0
Uranus: 8.69 m/s2 =0.886 g0
Mars: 3.72076 m/s2 =0.3794 g0
Mercury: 3.7 m/s2 =0.38 g0 (yes I know those are inconsistent; blame Wiki)
Io: 1.796 m/s2 =0.183 g
Luna: 1.622 m/s2 =0.1654 g0
Ganymede: 1.428 m/s2 =0.146 g
Titan: 1.352 m/s2 =0.138 g0
Europa: 1.314 m/s2 =0.134 g
Callisto: 1.235 m/s2 =0.126 g
Triton: 0.779 m/s2 =0.0794 g
Pluto: 0.620 m/s2 =0.0632 g
(The smaller moons of the outer solar system have more varied and/or less well measured surface gravities).
Found a PDF on the MSE. Probably can’t share the whole thing, but here are some selected bits:
So the MSE is actually combined with the MMO, and shares its propulsion module (the CPM). The CPM is quite high performance–52 kg dry mass and at least 570 kg propellant capacity, and 315 s Isp. It has 333 kg prop left after insertion.
The MSE+CPM composite separates once in Mercury orbit and descends from there (using somewhat above 4 km/s delta-V). But it’s got nearly a 1:4.5 mass fraction so it has plenty of juice (by my calcs, 4616 m/s).
New Glenn launch delayed yet another day to Mon Jan 13, same time (1:00 a.m. Eastern Time). Again, it’s due to rough seas at the landing barge.
Sorta funny that their original plan for the landing ship would have avoided the problem. They wanted to have a full-fledged ship which would be in motion at the time of landing, and use active stabilizers (which need the ship to be moving) to provide a stable platform. The rocket doesn’t much care if the target is moving as long as the motion is inertial. And a stabilized ship can provide a nice inertial platform.
But I guess that was too expensive and they saw that the barges worked out ok for SpaceX, so they used that instead. Lots simpler, but also more sensitive to rough seas.
I’d just like to point out that my wife’s Amazon purchases paid for this mission. That is all. You’re welcome!
Not sure yet about the best livestream, but here’s a reasonable one:
And another one coming up:
Scott Manley pointed out that Blue Origin New Glenn = B.O.N.G… Let’s light this BONG! Just 6 hours away.
Blue Origin’s native livestream (only with intro music at the moment):
Half an hour to go! They’re giving the usual disclaimers (“whatever happens, we’ll gather data and use those lessons for future launches”, etc.), but they do seem fairly confident. Looks like we’ll get some nice realtime views from Jacklyn (the drone ship). Supposedly it has Starlink installed.
I do have to wonder about the delays so far. Has SpaceX ever delayed a launch due to rough seas at the landing barge?
They have (though I don’t have an example off the top of my head). It’s somewhat uncommon since if weather is bad at the landing barge, it’s probably bad at the launch site as well, but it has happened.
A fairly recent example:
SpaceX was first planning to launch 21 Starlink internet satellites from Cape Canaveral Space Force Station on Wednesday, but rough seas in the Atlantic would have prevented the rocket booster from safely landing on the company’s drone ship. SpaceX opted to delay the launch to Thursday morning.
Only a few hours. Though for the Falcon 9, a few hours is the same as a few minutes–because they use subcooled propellant, they essentially have to launch right on time or else go through a full propellant recycle. As I recall, they can do this once fairly quickly, but more than that requires rechilling the propellant and it takes 24-ish hours for a recycle.
A couple minutes ago, they bumped the countdown. Moved the launch back about 20 minutes.
Not too unexpected for a first attempt. Currently at 34 minutes. They have a 3-hour window as I recall.