Tag: spaceflight

Another fuzzy Dawn image?

12:11 pm

July 9 Vesta image

Another image of Vesta from Dawn has been released. This image was taken on July 9 from a distance of 26,000 miles away. It is definitely an improvement over the previous image, with more small details becoming visible. However, I once again wonder about the softness of the image. Look at the limb of the planet. It is soft against the black sky. This is not what one would expect from perfectly focused camera.

Dawn goes into orbit around Vesta next week. We sure learn then for sure if there is a problem with its camera, or whether I am merely being a bit too nervous.

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NASA stalls, Texas lawmakers fume

10:12 pm

The law is such an inconvenient thing: In a bipartisan effort, Texas lawmakers roast NASA administrator Charles Bolden for not meeting mandated Congressional deadlines for Congress’s personally designed rocket, the program-formerly-called-Constellation.

The heavy-lift rocket and capsule that Congress insists NASA build is a complete waste of money and nothing more than pork. It will never get built, mainly because Congress has given NASA less money and less time to build it than they did for Constellation under the Bush administration. Unfortunately, the reason they continue to require NASA to build it is to provide pork to their districts.

In a perfect world this funding would be cut now, especially considering the state of the federal debt.
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Second ARTEMIS space probe about to enter lunar orbit

8:27 pm

The second ARTEMIS space probe will enter lunar orbit on Sunday.

“With two spacecraft orbiting in opposite directions, we can acquire a full 3-D view of the structure of the magnetic fields near the moon and on the lunar surface,” said Vassilis Angelopoulos, principal investigator for the THEMIS and ARTEMIS missions and a professor of space physics at UCLA. “ARTEMIS will be doing totally new science, as well as reusing existing spacecraft to save a lot of taxpayer money.”

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wings in space

12:49 pm

James McLane points out that the shuttle shape is not the only way to build a spaceship.

In an email to me Jim noted that he “is still trying to save NASA.” My response to him was that trying to save NASA right now is more hopeless than Don Quixote chasing a windmill. However, the engineering ideas he outlines in his essay are just the kind of innovative thinking required by the new private companies. And the more ideas the merrier!

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House Budget Bill Would Leave it to NASA To Apportion Bulks of Cuts

9:49 pm

The House bill that brings NASA’s budget back to 2008 levels essentially leaves it to NASA to figure out what to cut.

If true, what this means is that NASA itself will have to choose what it considers important. The one problem is that according to this article Congress is still requiring NASA to spend $3 billion on the program-formerly-called-Constellation. which gives the agency less flexibility in doling out the cash.

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A new image of Vesta from Dawn

2:36 am

Dawn continues to approach the large asteroid Vesta. Below is an image taken July 1st from about 62,000 miles. The image has a resolution of 5.8 miles per pixel.

Despite Vesta’s large size, 330 miles in diameter, it is nonspherical. This fact, combined with data that says it is differentiated with a core and mantle, suggests that it is the remains of a larger object that subsequently broke up.

Vesta from 62,000 miles

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Why some space junk is impossible to track

7:32 pm

This ISS status update, dated June 28, explains why the piece of space junk that flew past the station that day was such a surprise. (Hat tip to NASA engineer James Fincannon for pointing this out to me.)

Last night at ~6:00pm EDT, NASA Houston FTC (Flight Control Team) received notification of an upcoming “red threshold” conjunction of the ISS with a piece of orbital debris (Object 82618, UNKNOWN), with a TCA (Time of Closest Approach) this morning at 8:08am EDT, – which was too late to begin planning for a DAM (Debris Avoidance Maneuver). Therefore, FTC and crew made preparations for crew sheltering in Soyuz 26S & 27S. PC (Probability of Collision) at last tracking fix (7:20am) remained in the Red box, at ~0.003, with a miss distance of 0.25 km radial, 0.375 km downtrack, 0.570 m crosstrack. The necessary reconfiguration procedures (USOS hatches closed, etc.) began 1.5 hrs before TCA (6:38am EDT), and the six crewmembers ingressed their Soyuz vehicles. At 8:08am the object cleared the ISS with no impact, and shortly thereafter the crew was given the Go for returning to the ISS. [The late notification occurred because of the high air resistance (drag) of the object (~175 times higher than ISS) which made its trajectory very sensitive to small errors in atmospheric density predictions at the current solar flux. Due to the high drag, there is no chance of a recurrence of Object 82618).] [emphasis mine]

In other words, the piece of junk was probably something like a piece of insulation, very light but with a large area, much like a sail. Thus, as it flies through the thin atmosphere at 200 to 400 miles altitude its velocity and direction can easily change, making it difficult, if not impossible, to predict its future trajectory.

The good news is that these same conditions mean that the orbit of the object will quickly decay (“due to high drag”) so that it poses no future threat to the station.

Unfortunately, there are many other objects like this in orbit, and they all pose a threat, mostly because of the difficulty of reliably predicting their orbits.

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Mining the moon for water and nuclear fuel

10:16 am

Mining the moon for water and fuel.

Texas-based Shackleton Energy Company has already begun operations aimed at mining the Moon within the next few years. 

The company’s plans for mining and refining operations would involve melting the ice and purifying the water, converting the water into gaseous hydrogen and oxygen, and then condensing the gases into liquid hydrogen, liquid oxygen and hydrogen peroxide, all potential rocket fuels.

Shackleton CEO Dale Tietz says the water extracted would be used almost exclusively as rocket fuel to power operations both within Low Earth Orbit (LEO) – such as space tourism and the removal of space-debris – on the Moon, and further out into space. ‘We are a for-profit business enterprise moving forward, and so we are only going there really for one reason and that is to mine, prospect mine and harvest water for rocket propellant production,’ says Tietz.

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Dawn’s approach to Vesta continues

9:35 am

Dawn’s approach to Vesta continues.

Starting at the beginning of the approach phase on May 3, Dawn interrupted thrusting once a week to photograph Vesta against the background stars. These images help navigators determine exactly where the probe is relative to its target. This technique does not replace other means of navigation but rather supplements them. One of the principal methods of establishing the spacecraft’s trajectory relies on accurately timing how long it takes radio signals, traveling, as all readers know, at the universal limit of the speed of light, to make the round trip between Earth and Dawn. Another uses the Doppler shift of the radio waves, or the slight change in pitch caused by the craft’s motion. These sensitive measurements remain essential to navigating the faraway ship as it sails the interplanetary seas.

Despite the very slow approach, the distance is small enough now that observing Vesta weekly is no longer sufficient. To achieve the navigational accuracy required to reach the intended orbit in early August, last week the frequency of imaging was increased to twice per week. In each session, half of the pictures are taken with long exposures to ensure many stars are detectable, thus overexposing the much brighter disc of the nearby Vesta. The other half use short exposures to ensure that the rocky world shows up correctly so its precise location can be measured. The visible and infrared mapping spectrometer has been commanded to observe Vesta during three of these sessions, each time providing valuable information that will help scientists select instrument settings for when Dawn is close enough to begin its detailed scientific measurements.

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