Hello Space Fans and welcome to another edition of Space Fan News.
This week, ESA’s Philae Lander, a part of the Rosetta mission to comet 67P has been
found; also, the Rosetta spacecraft orbiting said comet will smash into it on Sept 30th;
and SpaceX announces that it is ready to resume launches later this year.
On September 5th, the European Space Agency announced that the Philae lander, a part of
the Rosetta mission to Comet 67P/Churyumov–Gerasimenko, announced that they have found the lander
that had bounced and lost contact with on November 12, 2014.
With less than a month left in the Rosetta mission, members of the team were able to
get these really great, detailed images using the onboard OSIRIS narrow-angle camera as
the orbiter came within 2.7 kilometers of the surface of the comet.
The images clearly show the main body of the lander, along with two of its three legs.
These images also show the orientation of the lander: on its side wedged into a dark
crevice on the comet.
In case you don’t know what happened, on November 12th, 2014, the Philae lander was
supposed to touch down on the comet surface and used two harpoon-like spears to grab onto the surface
Something went wrong though, maybe the harpoons fired too soon or for whatever reason caused
the lander to bounce, fly for two hours and then came to rest here, in a location called
Abydos on the comet’s smaller lobe.
After that, the lander worked for three days until the primary battery was drained and
the lander then went into hibernation.
Looking at this, it is easy to see why establishing communications was so hard and why the batteries
died lying in that dark crevice.
With no sunlight to recharge the batteries, it was game over until just last June and
into July of this year as the comet came closer to the Sun, more power became available and
communication was established briefly.
After that, the lander was forever silent, but they still wanted to see if they could
find where the heck the lander was.
Since the mission was ending this month, people were starting to worry that the lander would
be lost forever.
So these images came with a big sigh of relief.
Now that they know where the lander is as well as its orientation, astronomers can make
better sense of the data that Philae was able to gather during the three days while it was working
These images put what scientists call ‘ground truth’ confirmation to the lander’s fate.
Ground truth just means actual observations - they can see it with their own eyes -
instead of models or simulations based on the best available data.
So everyone at ESA working on the Rosetta mission is thrilled to have found the lander
during the final month of the mission because, well…
This brings me to my second story for this week: September 30th marks the final days
of the Rosetta mission because on that day, just a couple of weeks from now, mission planners
are going to put the spacecraft currently in elliptical orbits, that since August 9th
have been bringing the Rosetta orbiter progressively closer to the comet surface.
On its closest and final flyby, scheduled for September 24th, the orbiter may get as
close as 1 km above the surface, closer than it has ever been.
Next, after this final approach, a short series of manoevers will be executed designed to
line up Rosetta with the target impact site.
These will take several days to complete as it transfers from being in an elliptical orbit
and onto a trajectory that will eventually take it to the comet’s surface on September 30th
This should be really cool to watch.
What’s going to happen is they are going to get the spacecraft into position to hit
the comet about 20 km above the surface, then put it in a free fall.
The instruments onboard will collect data during the descent and returned to Earth just
before it hits.
They expect the impact to occur within 20 minutes of 10:40 UT, they aren’t sure exactly
because they won’t be sure to the exact trajectory until the spacecraft gets into position.
Rosetta is already starting to feel the effects of gravity of the comet as it gets closer,
and taking into account the 40 minute signal delay between Rosetta and Earth, they expect
to know sometime within 20 minutes of 10:40 UT that it hit.
Here’s how they expect to know precisely when Rosetta hits the comet.
This is data from a spectrum analyser showing the signal received by ground stations.
When that peak that you see on the right goes away, the spacecraft is presumed dead and
has hit the comet.
It’s going to hit in a region called Ma’at, on the smaller of the two lobes of the Comet.
It is home to several active pits more than 100 meters in diameter and 50-60 meters deep
and is also where a number of the comet’s dust jets originate.
So, you may be wondering, how fast will it be going when it hits?
The current predictions are that it will be going 90 cm/s or about 2 mph.
They expect the impact will damage the solar panels and other appendages on the spacecraft
and the energy dissipated from this will probably keep any bouncing the spacecraft from exceeding
the escape velocity of the comet, preventing it from returning to orbit around it.
Also, on a side note, the final trajectory of Rosetta will be on the opposite side of
the comet that the Philae lander is currently resting so it won’t be able to see the orbiter
as it plunges to the surface.
It’s incredible to think that it took Rosetta 10 years to get to Comet 67P, studied it for
two years and is now going to die.
These final sets of science operations should culminate in a better understanding of comet
structure, composition, behavior and properties of comets in our solar system.
Well done Rosetta Team!
I’ll tell you how it went in early October once the data are back.
Finally, in a followup to last last SFN where I told you about the explosion rocking launch
complex 40 at Cape Canaveral, SpaceX announced this week that it will try to resume launches
this November from Launch pad 39A.
This is the second of two launchpads that SpaceX has available in Florida and while
the damage to launch complex 40 is extensive, apparently, and may take up to a year to repair,
pad 39a will be available in November to continue launches.
SpaceX is still investigating the root cause of the September 1st explosion, and many are
wondering if this is just wishful thinking, but they are targeting November as the time
to get back to business.
I’ll let you know.
Well, that’s it for this week Space Fans, thanks so much to all of SFN patreon patrons
whose support makes these episodes possible, thank all of you for watching, and as always,
Keep Looking Up!