Year: 2018

NASA approves Dream Chaser design

9:04 am

Capitalism in space? Sierra Nevada has, after several years of work, obtained NASA’s approval of the design of its Dream Chaser mini-shuttle, and will now begin construction.

I put a question mark in the header above because I am no longer sure Sierra Nevada is building a privately designed and privately owned spacecraft for the launch market. It seems that they have been captured entirely by NASA, and will instead be building the spacecraft NASA wants, which might raise costs enough to make this vehicle unaffordable for other customers.

The situation is understandable. Sierra Nevada does not have the independent capital that gives SpaceX its independence. It needs NASA to get this ship built, and thus will do whatever NASA demands. I just worry that NASA, unconcerned about cost (as is every agency in the federal government today), will spoil Dream Chaser’s viability in the commercial market.

2 comments

Trump administration reorganizes military space into single command

8:55 am

The Trump administration yesterday announced that it is doing what many in the military space sector have been proposing for several years. reorganizing all military space departments into a single command.

This is not a space force, but a realignment of the military bureaucracy in an effort to make space operations more focused and efficient. Whether it will actually do that I have my doubts. My impression from the news reports is that the military is using this as an opportunity to create a new upper management layer, thus increasing the size of bureaucracy.

10 comments

Today’s launch update

8:48 am

This post will change throughout the day. At the moment, India has successfully finished out the year with its seventh launch, placing an Indian military satellite into orbit with its GSLV rocket.

Seven launches matches India’s previous high from two years ago, but it is also far below their predicted 12 launches. I have a hunch next year will see that jump in launches, especially now that they have now successfully launched their GSLV rocket multiple times.

Meanwhile, Blue Origin is now targeting December 21, in two days, for its suborbital flight of New Shepard, while SpaceX decided to hold off on a launch today of an Air Force GPS satellite while it analyzes more closely the technical issue that scrubbed yesterday’s launch.

An Arianespace Soyuz rocket is set to launch a French military satellite from French Guiana very shortly, while a ULA Delta-4 Heavy is on track for the launch of a National Reconnaissance Office (NRO) spy satellite later today. I will provide updates later today.

UPDATE: Arianespace has successfully launched the French military satellite, using a Soyuz rocket. This was the eleventh launch for Arianespace this year, and its third Soyuz launch. Some might assign these Soyuz launches to Russia, but I consider them European launches because the business comes from Arianespace.

UPDATE: The ULA’s launch today was scrubbed due to the detection of a fuel leak. No word on when they will try again.

5 comments

Dark dunes, wedding cake mesas, and dust-filled gullies

1:06 pm

Dark dunes, wedding cake mesas, and dust-filled gullies

Cool image time! The photo on the right, reduced, rotated, and cropped slightly to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and issued by the spacecraft science team in its December image release.

They didn’t give this image a caption. The release title, “Arabia Terra with Stair-Stepped Hills and Dark Dunes,” significantly understates the wild variety of strange features throughout this terrain. Normally I crop out one section of the photographs I highlight to focus on the most interesting feature, but I couldn’t do it this time. Click on the image to see the full resolution version. Take a look at the complex wedding cake mesas in the lower left. Look also at the streaks of dust that I think are filling the gullies between these hills. In the image’s upper left are those dark dunes, scattered between dust ripples and small indistinct rises and what appears to be a drainage pattern descending to the north. Interspersed with these dunes near the center of the image are several perched crater floors, indicating that the crater impacts happened so long ago that the surrounding terrain had time to erode away, leaving the crater floor hanging like a small plateau.

On the right the two largest mesas rise in even stair-stepped layers that would do the mesas in the Grand Canyon proud.

This could very well be the coolest image I have ever posted. Everywhere you look you see something different, intriguing, and entirely baffling.

Arabia Terra covers the largest section of the transition zone between Mars’s high cratered south and its low flat northern plains, where some scientists believe an intermittent ocean might have once existed. It lies to the east of Valles Marineris, and is crater-filled with numerous intriguing geology, as this image most decidedly illustrates. In this particular case it shows the floor of one of the region’s mid-sized craters.

2 comments

FCC: SpaceX’s Starlink satellites can kill

9:43 am

The sky is falling! The FCC has calculated that fragments from SpaceX’s planned Starlink constellation of almost 12,000 satellites pose a risk of landing on humans on Earth.

SpaceX estimates that several kilograms of each 386-kilogram Starlink could reach the Earth’s surface with sufficient energy to harm or kill someone. NASA has fixed this figure at 15 joules—about the same wallop as a baseball traveling at 51 kilometers per hour. Depending on the satellite’s configuration, iron thruster components, stainless steel reaction wheels, or silicon carbide mirrors could survive the journey from orbit to your head.

…In March and June 2017, the FCC calculated the aggregate risk to humans from the entire constellation. Assuming the 11,927 satellites are launched on a regular basis, they will fail in the same way. Starting around six years from the first launch, an average of five satellites a day will reenter the Earth’s atmosphere, each with a tiny chance of failing to completely burn up, resulting in a part that could hit someone.

But with more than a thousand satellites falling a year, those tiny risks add up. The FCC figured out that, over their lifetime, satellites in the LEO shells posed a 1 in 5 risk of hurting or killing someone, and the VLEO satellites carried a 1 in 4 risk. IEEE Spectrum’s calculations using SpaceX’s most up-to-date information suggests that the overall risk of debris from the constellation causing an injury or death will be 45 percent.

Rather than demanding that we restrict or change what SpaceX does, I see this as an opportunity for someone designing robot satellites designed to clean up space junk. Offer your services to SpaceX. They get their problem solved easily, and you make some money.

11 comments

Comparing Ryugu and Bennu

9:30 am

Link here. As much as they are alike, which is not surprising as they both come from the same asteroid family, the article notes the surprising differences.



Both asteroids are also liberally strewn with boulders – a challenge to mission planners on each team, who hope to descend close enough to scoop up samples for return to Earth. “It’s certainly more rugged than we had expected,” Lauretta says. 

But while boulders on Ryugu look to be unpleasantly ubiquitous, Bennu’s terrain is more varied, with more-obvious places where a safe touchdown might be possible. And, Lauretta notes, the OSIRIS-REx spacecraft is only recently arrived.

“We have a long time to explore and make the crucial decisions about where to go,” he says.

The biggest difference has to do with water. Even though scientists believe them to be portions of the same parent body, which broke apart between 800 million and one billion years ago, Bennu appears to be water rich, while Ryugu is less so. Within a week of arrival, infrared spectrometers on OSIRIS-REx were finding evidence of water-bearing minerals, and not just in localised patches. “We saw this in every single one of the spectra we have taken to date,” says Amy Simon, of NASA’s Goddard Space Flight Centre in Greenbelt, Maryland. 

One of the reasons Bennu was chosen as OSIRIS-REx’s target, Lauretta says, was the hope it would be rich in water, and possibly in organic compounds.

The similarities and differences in the samples both spacecraft will bring back will be most revealing.

0 comments

Three launches scrubbed

9:15 am

Capitalism in space: Both SpaceX and Blue Origin scrubbed planned launches today due to what appear to be minor technical issues.

SpaceX was launching a GPS satellite for the military, while Blue Origin was going to fly its New Shepard suborbital spacecraft on its third flight. SpaceX will try again tomorrow, while Blue Origin has not yet announced a new launch date.

Meanwhile, ULA’s attempt to launch a National Reconnaissance Office (NRO) spy satellite tonight with its most powerful rocket, the Delta 4 Heavy, faces bad weather, with only a 20% chance of launch.

UPDATE: I missed a third launch scrub today, Arianespace’s attempt to launch a trio of French military satellites using a Soyuz rocket from French Guiana. They will try again tomorrow.

This means there will be three launch attempts tomorrow, since India plans a launch of its GSLV rocket as well.

1 comment

New Horizons sees no hazards, will do closest fly-by of Ultima Thule

9:04 am

After three weeks of intense observations and seeing no significant objects orbiting close to the Kuiper Belt object Ultima Thule, the New Horizons team has decided to go for the closest fly-by on January 1, 2019.

After almost three weeks of sensitive searches for rings, small moons and other potential hazards around the object, New Horizons Principal Investigator Alan Stern gave the “all clear” for the spacecraft to remain on a path that takes it about 2,200 miles (3,500 kilometers) from Ultima, instead of a hazard-avoiding detour that would have pushed it three times farther out. With New Horizons blazing though space at some 31,500 miles (50,700 kilometers) per hour, a particle as small as a grain of rice could be lethal to the piano-sized probe.

We should begin to see more detailed images soon. Because of the speed in which New Horizons is traveling, it will not get very close until it is almost on top of Ultima Thule, so the best images will all occur over a very short span of time.

0 comments

Saturn’s rings are dying

8:56 am

Using new ground-based observations, scientists now predict that Saturn’s rings are dying at the fastest predicted rate, and will disappear within 300 million years, at the most.

Dr Tom Stallard, Associate Professor in Planetary Astronomy at the University of Leicester and Dr James O’Donoghue, who studied for his PhD at the University of Leicester, have found that Saturn’s rings are dying at the maximum rate estimated from Voyager 1 and 2 observations made decades ago.

The rings of ice are being pulled into Saturn by gravity as particles of ice under the influence of Saturn’s magnetic field. Dr O’Donoghue, who now works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland said: “We estimate that this ‘ring rain’ drains the equivalent of an Olympic-sized swimming pool from Saturn’s rings in half an hour. The entire ring system will be gone in 300 million years.”

Dr O’Donoghue believes that the rings could even disappear quicker than this. “Add to this the Cassini-spacecraft detected ring-material falling into Saturn’s equator, and the rings have less than 100 million years to live.”

Over the decades I have read numerous papers by scientists saying that rings this bright and large must be a relatively short-lived event, and that we are lucky to have seen them. This research only reinforces this conclusion.

At the same time, we do not yet know the frequency or the cause of the events that give rise such bright rings. It could be that such rings are short-lived, but happen frequently enough that it is still not rare to see them in any solar system. And we won’t know this until we get a more complete census of many solar systems, seen up-close.

6 comments

“What do we do now?“

12:33 pm

LM ascent engine

One of the advantages one gets from writing books and giving lectures about them is that you get to see some interesting places and meet some interesting people. This is what happened to me last week when I gave two lectures about the Apollo 8 mission to the Moon on consecutive nights to three different Buffalo aerospace organizations at two different venues. My entire visit was as a guest of the Niagara Frontier Section of American Institute of Aeronautics and Astronautics, as part of its Distinguished Lecturer program, something I have participated in now for almost a decade.

The first lecture was at the Niagara Aerospace Museum. Prior to my evening talk Don Erwin, a member of the museum’s board of trustees, gave me detailed tour of the museum and its holdings, which include a wealth of artifacts going back to the very beginnings of flight and running through the Apollo lunar missions. Many of aviation’s first innovators came from the western New York area, and the companies they created ended up building important components for the later U.S. effort to get to the Moon.

looking into ascent engine nozzle

Above on the right is one of their more significant artifacts, a lunar module ascent engine. Built mostly by Bell Aerospace, this particular engine was used to test the engine to make sure the design would work. It had to work, by the way, since it had no back-up and if it failed then the astronauts would have been stranded on the Moon.

Since it really only had to work reliably once, however, the nozzle was made of ablative material rather than a heavier metal. The second image on the right looks into that nozzle, where you can see the result of the various test firings done to prove out the engine. There is obvious wear to the interior of the nozzle.

What made this museum especially fun was how accessible everything was.
» Read more

6 comments
1 … 3 4 5 6 7 … 155