SpaceX successfully completed their first flight for the National Reconnaissance Office, carrying an undisclosed classified payload to orbit, designated NROL-76. As is typical for NRO launches, coverage of the climb to orbit went only as far as first stage burnout. However, SpaceX still had plenty of first stage footage still to produce, as the stage returned to land back at the Cape. As a result of that and the favorable lighting conditions to view the rocket climbing away from the historic LC-39A complex, using the exceptional long-range tracking cameras available at KSC, this may be the most spectacular first stage flyback footage yet:
Tianzhou-1 has docked with the unoccupied Tiangong-2 station and completed an on-orbit refueling demonstration. The entire operation took five days. Tianzhou-1, which is loaded with inert bags to act as mass models of station supplies, will remain at the station for a few months, conducting other tests, before undocking for a free-flight phase of the mission before it is commanded to a destructive reentry.
Tianzhou-1 is the heaviest payload ever launched by China, bigger even than the Tiangong-1 and Tiangong-2 space stations, which speaks to the high aspirations they have for their subsequent stations. They are planning something substantial, and capable of continuous occupation. Tianzhou itself is designed to supply the needs of three crewmembers (in food, water, supplies, and breathable air) for a full month.
Cassini’s first dive inside the rings has been completed, and the spacecraft has regained contact with Earth, right on schedule. As I type this, Cassini is busy downlinking data from the close pass via the DSS 43 dish, the largest one at the Deep Space Network’s Canberra, Australia location. (If you’re ever curious who’s talking to who in deep space, visit NASA’s DSN Now page.) The reason they were out of contact during the pass was that Cassini was oriented so that the high gain antenna faced into the direction of travel, using the massive dish as a shield.
There’s still considerable data still to be downloaded, but JPL has posted the first images, which are in the vicinity of Saturn’s north pole. The north pole is home to Saturn’s strange hexagon feature, now seen in greater detail than ever before. These raw, unprocessed images are just a taste of what will be available when the whole data set is down.
In the wee hours of the morning today, Cassini made its 127th and final close flyby of Saturn’s giant moon Titan, the second largest satellite in the solar system. There were many targeted observations planned on this final encounter, including radar studies of the “magic island”, a landform that has appeared and disappeared in Ligeia Mare, one of Titan shallow methane seas. It’s presumed this disappearing trick is the work of changing levels in the sea, but more data is needed.
But there’s more to this flyby than just some great science. Cassini has relied heavily on Titan’s mass to adjust its trajectory for very little fuel expenditure, and today was no exception. Today, Cassini used Titan’s gravity to lower its orbit significantly, bringing the periapsis (the low point) within the rings, and shortening the entire orbit to just about a week. Cassini will make twenty two dives into the area within Saturn’s rings, low enough to begin to directly sample some of Saturn’s tenuous upper atmosphere, gradually sinking on each closest approach until finally, next September, its predicted to impact the giant planet’s cloud decks and burn up.
It’s bittersweet, to be sure. Cassini has functioned like a champ, long past its original design life. But all things must come to and end, and Cassini will go out with a bang.
So as we prepare to say farewell in a few months, here’s a parting shot from Cassini: the last photograph it will be able to take of the Earth and Moon. This was taken on April 12, taking advantage of a viewing geometry that will not occur again on the mission, where Earth peeked through the gap between the A ring and the F ring:
Yesterday didn’t just see the launch of Soyuz MS-04; the Chinese also launched Tianzhou-1, the experimental first model of their new autonomous cargo vehicle to support their crewed space station program. Tianzhou-1 will dock several times with the now-uncrewed Tiangong-2 space station to validate the performance of the docking system and its ability to offload propellants into the station (a feature that has only ever been available in two other cargo vessels, Progress and Europe’s Automated Transfer Vehicle). This launch occurred using a Long March 7 rocket flying out of the new Wengchang Space Center on Hainan Island. Both the Long March 7 and Wengchang were built largely with the crewed program in mind; Hainan is much further south than any other Chinese launch centers, improving the available upmass. Long March 7 will be used to fly both Tianzhou and Shenzhou (the crewed vehicle).
The latest crewed mission to the ISS has arrived: Soyuz MS-04, with Soyuz commander (and future Expedition 52 commander) Fyodor Yurchikhin and flight engineer Jack Fisher. The two men share an interesting interagency history — Yurchikhin was one of the first cosmonauts to fly aboard Shuttle, and Fisher is one of the first (possibly *the* first, I’m not sure) American astronaut to serve as Soyuz flight engineer, a situation necessitated by Roscosmos’ decision to reduce their crew size in an effort to save money. The empty third seat was filled with supplies, and when they return, they will be joined by current Expedition 51 commander Peggy Whitson, whose mission has been extended a few months.
It was a beautiful liftoff from the plains of Kazakhstan:
As per current protocol, they made a rapid ascent profile, docking on the fourth orbit:
This brings Station up to a crew of five.
The rover that doesn’t know how to quit, Mars Exploration Rover B “Opportunity” has just departed “Cape Tribulation”, a feature on the rim of Endeavour Crater on Mars. It’s spent the last 30 months at this location, conserving power over the Martian winter (since unlike Curiosity, it’s solar powered), and now it’s ready to move on. The next destination is a nearby valley in the huge crater’s rim, called “Perseverance Valley”. It’s a good name for a valley soon to be explored by a spacecraft 13 years into its 3-month mission. 😉 Opportunity will begin by studying the top of the valley, then move down it in the sort of pattern you’d expect a geologist to take while studying erosion and deposits that may explain how the valley was formed.
Here’s a final full-color panoramic look at Cape Tribulation: